HomeMy WebLinkAboutRES 44621
CITY OF RENTON, WASHINGTON
RESOLUTION NO. 4462
A RESOLUTION OF THE CITY OF RENTON, WASHINGTON, ADOPTING THE CITY OF
RENTON URBAN FOREST MANAGEMENT PLAN 2022-2032.
WHEREAS, the Growth Management Act encourages planning for open space and
recreational needs of a community to be integrated with planning for other needs; and
WHEREAS, the City of Renton Urban Forest Management Plan 2022-2032 (the “Plan”) is
compatible with the intent of the City's adopted Comprehensive Plan; and
WHEREAS, the City began the update process for the Plan in April of 2021; and
WHEREAS, the Plan has been developed with extensive community outreach in
conjunction with residents, property owners, stakeholders, local businesses, community
partners, public and private agencies and institutions, and non-profit organizations; and
WHEREAS, urban forests provide environmental benefits, opportunities for
recreation, community connections, natural resources and habitat, offering places for quiet
reflection, and experiencing nature; and
WHEREAS, the Plan is a comprehensive update of the 2009 Urban and Community
Forestry Development Plan and therefore supersedes and replaces the 2009 plan. It represents
a collaborative effort between the Parks and Recreation and Community and Economic
Development Departments with support from all City departments, and reflects the public's
desire to provide the opportunity for the community to connect to, participate in, support, and
encourage a healthy environment and active lifestyle; and
WHEREAS, the Plan creates a 10 year vision for trees on public property in the City of
Renton – the urban forest; describes current and future needs; and identifies policies,
RESOLUTION NO. 4462
2
implementation strategies, and a maintenance program to enhance and sustain trees as a
critical piece of green infrastructure for a livable community; and
WHEREAS, updating and adopting the Plan maintains the City's status as an Arbor
Day Foundation ‘Tree City USA;’ and
WHEREAS, the Plan was developed in conjunction with citizen feedback and a
collaborative team; and
WHEREAS, this matter was duly referred to the Parks Commission, Planning Commission,
and Planning & Development Committee for investigation, study, and review; and
WHEREAS, the Planning Commission held a public hearing on December 1, 2021,
considered all relevant matters, and heard all parties in support or opposition, and
subsequently forwarded a recommendation to the City Council; and
WHEREAS, the Plan was subject to a State Environmental Procedure Act (SEPA)
review pursuant to Chapter 43.21C RCW and successfully passed a Washington State
Department of Commerce 60-day review;
NOW THEREFORE, THE CITY COUNCIL OF THE CITY OF RENTON, WASHINGTON, DO RESOLVE
AS FOLLOWS:
SECTION I. The City Council hereby adopts the Plan, attached hereto as Exhibit A and
incorporated by this reference, and directs the Administration to draw up a work program
to begin implementing the Plan. The Plan shall remain in full force and effect until further
revised, amended, and modified as provided by law.
RESOLUTIONNO.4462PASSEDBYTHECITYCOUNCILthis14thdayofFebruary,2022.Jason.Seth,CilerkAPPROVEDBYTHEMAYORthis14thdayofFebruary,2022.4oavone.MayorApprovedastoform:ShaneMoloney,CityAttorneyRES-P&R:1901:2/7/20223
RESOLUTION NO. 4462
4
EXHIBIT A
CITY OF RENTON
URBAN FOREST MANAGEMENT PLAN 2022-2032
CITY OF RENTON, WASHINGTON
Urban Forest Management Plan
2022-2032
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ACKNOWLEDGMENTS
This project was made possible thanks to the support and contributions of the following
City of Renton Staff and Officials:
Mayor
Armondo Pavone
Chief Administrative Officer
Ed VanValey
City Council
Ryan McIrvin, City Council President
James Alberson
Valerie O’Halloran
Ruth Pérez
Edward Prince
Carmen Rivera
Kim-Khánh Văn
Judith Subia, City Council Liaison
Parks Commission
Shun Takano, Chair
Cynthia Burns
Al Dieckman
Larry Reymann
Timothy J. Searing
Troy Wigestrand
Marlene Winter
Planning Commission
Shannon Matson, Chair
Charles Seil, Vice Chair
Josephine Bayan, Secretary
Dana Rochex
David Fleetwood
James Alberson
Kevin Poole
Mara Fiksdal
Sunayana Kannur
Executive Services (ES)
Maryjane Van Cleave, Communications &
Engagement Director
David Neubert, Communications
Manager
Sheila Cowley, Communications
Specialist 1
City Attorney
Shane Moloney
Community & Economic Development
(CED)
Chip Vincent, Administrator
Angie Mathias, Long Range Planning
Manager
Human Resources & Risk Management
(HR&RM)
Ellen Bradley-Mak, Administrator
Parks and Recreation (PR)
Kelly Beymer, Administrator
Erica Schmitz, Parks Planning and
Natural Resources Director
Ian Gray, Urban Forestry & Natural
Resources Manager
Public Works (PW)
Martin Pastucha, Administrator
Collaborative Team Members
Angelea Weihs, Associate Planner (CED
Planning Division)
Cailín Hunsaker, Parks & Trails Director
(PR Parks & Trails Division )
Drey Hicks, Neighborhood Program
Coordinator (ES Communications &
Engagement Division )
Gary Del Rosario, GIS Analyst 2 (ES
Information Technology Division )
Joseph Farah, Utility Engineering
Manager (PW Utilities Division )
Kelsey Urban, Risk Manager (HR&RM)
Patrick Zellner, Street Maintenance
Manager (PW Maintenance Service s
Division)
Vanessa Dolbee, Plan ning Director
(CED Planning Division)
Vangie Garcia, Transportation Planning
Manager (PW Transportation
Engineering Division)
This Plan was produced by PlanIT Geo, Inc. (PlanIT Geo) and Peninsula Environmental Group in
collaboration with the City’s Urban Forestry & Natural Resources Manager, Ian Gray, and the
Collaborative Team.
CITY OF RENTON, WASHINGTON
URBAN FOREST MANAGEMENT PLAN
10-YEAR UPDATE
January 2022
Renton, WA Urban Forest Management Plan 10-year Update Jan2022 i | P a g e
TABLE OF CONTENTS
Executive Summary .............................................................................................................................................. I
Introduction ........................................................................................................................................................... 4
Benefits of the Urban Forest ............................................................................................................................ 5
Historical Background ........................................................................................................................................ 9
Current State of Renton’s Urban Forest ...................................................................................................... 13
Urban Tree Canopy Cover ......................................................................................................................................................... 15
Urban Tree Canopy Cover Change ..................................................................................................................................... 18
Urban Tree Equity ......................................................................................................................................................................... 20
Structure of the Public Tree Population ........................................................................................................................ 24
Public Tree Population Size Class Distribution (Relative Age) ....................................................................... 28
Value and Benefits of the Public Tree Population................................................................................................. 30
Renton’s Urban Forestry Program ............................................................................................................... 34
Current Urban Forest Management Challenges ..................................................................................... 35
Programs Managing Renton’s Urban Forest ............................................................................................ 39
Program Organization ................................................................................................................................................................ 39
Interdepartmental Management of Trees ................................................................................................................... 39
Parks Planning and Natural Resources Urban Forestry Program ............................................................... 40
Urban Forest Benchmark Comparisons ........................................................................................................................ 44
Urban Forest Audit ........................................................................................................................................................................ 47
Program Needs .................................................................................................................................................... 49
Public Tree Maintenance ......................................................................................................................................................... 49
Urban Forestry Program Staffing to Support Sustainable Management .............................................. 57
Workflows and Standard Operating Procedures .................................................................................................... 62
Tree Canopy Cover Goals .......................................................................................................................................................... 64
Tree Planting Initiative ............................................................................................................................................................... 75
Post-Planting Care and Young Tree Maintenance ................................................................................................ 80
Funding Mechanisms ................................................................................................................................................................ 86
Community Engagement ........................................................................................................................................................ 93
Urban Forestry Goals, Objectives, and Strategies ................................................................................ 103
Goals, Objectives, and Strategies ...................................................................................................................................... 104
Key Strategies ................................................................................................................................................................................. 107
Evaluation ........................................................................................................................................................... 108
Implementation Schedule .............................................................................................................................. 111
Summary and Conclusion .............................................................................................................................. 112
Appendices ............................................................................................................................................................. A
Appendix A. Implementation Schedule.......................................................................................................................... B
Appendix B. Solutions Workbook and Possible Guidelines for Tree and Sidewalk Conflicts ..... F
Appendix C. Guidance to Develop a Tree Advisory Committee ..................................................................... Q
Appendix D. 2021 Urban Forest Audit System Results ........................................................................................... T
Appendix E. Risk Tree Management Plan ................................................................................................................... EE
Appendix F. Urban Forest Pest Ready Assessment ............................................................................................. QQ
Appendix G. References ........................................................................................................................................................... VV
Renton, WA Urban Forest Management Plan 10-year Update Jan2022 ii | P a g e
TABLES AND FIGURES
TABLES
Table 1. Distribution of public trees by Site Design ............................................................................................................................. 24
Table 2. Public tree genera diversity (top 10) ........................................................................................................................................... 25
Table 3. Public tree species diversity (top 10)........................................................................................................................................... 26
Table 4. Summary of Renton’s tree size distribution compared to the ideal distribution ..................................... 29
Table 5. Summary of ecosystem services, benefits, and values of Renton's public trees ...................................... 30
Table 6. Summary of the annual benefits provided by Renton’s public trees* .............................................................. 32
Table 7. Summary of the benefits and services of trees in natural areas ............................................................................ 33
Table 8. Annual investments in the management of street and park trees ...................................................................... 41
Table 9. Summary of the 2022 budget for the Urban Forestry Program’s Administration* ................................. 42
Table 10. Arbor Day Foundation Tree City USA communities examined during the benchmarking… ......... 45
Table 11. Summary of phase 1 benchmarking research results (Tree City USA dataset) .......................................... 46
Table 12. Summary of phase 2 benchmarking research results (2014 Census, Hauer et al.) ................................. 46
Table 13. Outcomes of the urban forest auditing process for Renton, WA ........................................................................ 47
Table 14. Public tree maintenance needs by Site Design based on an analysis of August 2021… .................... 50
Table 15. Current and recommended maintenance regimen for Renton’s public tree population… ........... 53
Table 16. Assumptions for estimating the additional costs to effectively maintain the public tree… ............ 53
Table 17. Recommended streets for priority tree maintenance by Community Planning Area ...................... 56
Table 18. Estimated staff and associated costs to maintain public trees on a 7 -year rotation .......................... 59
Table 19. Summary of costs .................................................................................................................................................................................. 59
Table 20. Comparison of in-house and contracted pruning for a 7-year public tree pruning cycle ............. 60
Table 21. Summary of the current and future Urban Forestry Program services and budgets ........................... 61
Table 22. Long-term tree canopy goals (by 2042) and planting targets by Community Planning Area ..... 67
Table 23. Summary of the recommended tree canopy goals and planting targets for Renton ....................... 74
Table 24. Parcel tax options and provisions for Renton's Urban Forestry Program ................................................... 89
Table 25. Summary of financing options for Renton’s urban forest ........................................................................................ 91
Table 26. Renton’s urban forest benchmark values ........................................................................................................................ 109
Table 27. Evaluation, monitoring, and reporting techniques to achieve the urban forestry goals ................ 110
Table 28. Description of possible alternative solutions for tree and construction conflicts .................................. M
Table 29. Urban Forest Pest Ready Assessment from the WA State Urban Forest Pest Readiness… ...........QQ
Renton, WA Urban Forest Management Plan 10-year Update Jan2022 iii | P a g e
FIGURES
Figure 1. Framework of the Urban Forest Management Plan ......................................................................................................... 2
Figure 2. Overview of the ecosystem benefits and services provided by trees in communities … ........................ 5
Figure 3. The street tree pictured adds $7,593 to the price of the house it fronts and $7,098 to th e… ........... 7
Figure 4. Depiction of the various types of landscapes that comprise Renton's urban forest ............................. 14
Figure 5. Maintenance responsibility of trees comprising Renton's urban forest ......................................................... 15
Figure 6. Renton’s 2018 Tree Canopy Assessment results ............................................................................................................... 15
Figure 7. Map displaying Renton's tree canopy and vegetative area for possible tree plantings (2018) ...... 16
Figure 8. Existing tree canopy cover by Community Planning Area ....................................................................................... 17
Figure 9. Existing tree canopy cover by Zoning Type (consolidated classifications) ................................................... 17
Figure 10. Citywide tree canopy cover change ........................................................................................................................................ 18
Figure 11. Tree canopy cover change by Community Planning Area....................................................................................... 18
Figure 12. Tree canopy cover change by Zoning Type (conso lidated classifications).................................................. 18
Figure 13. Example of canopy cover differences in two Renton neighborhoods ......................................................... 20
Figure 14. Map displaying the Tree Equity Scores by Census Block Groups in Renton… ........................................... 21
Figure 15. Comparison of Tree Equity Scores for cities near Renton, WA ........................................................................... 22
Figure 16. Count of Census Block Groups for each Tree Equity Score range .................................................................... 22
Figure 17. Public tree genera diversity ........................................................................................................................................................... 25
Figure 18. Public tree species diversity .......................................................................................................................................................... 26
Figure 19. Leaf profiles of the most common public trees (not to scale)............................................................................. 26
Figure 20. Distribution by Diameter (DBH) class within site design classifications .................................................... 28
Figure 21. Distribution of public trees by diameter (DBH) class compared to the ideal distribution............. 28
Figure 22. Illustration of the benefits and services provided by public trees ................................................................... 32
Figure 23. Structure of Renton's Urban Forestry Program ............................................................................................................. 39
Figure 24. a) Relationship between pruning cycle length and condition class rating… ............................................ 51
Figure 25. As the years between street tree pruning increases, tree health and safety decrease … ................. 52
Figure 26. Recommended priority tree maintenance by street corridor and planning area ..............................55
Figure 27. Renton's 10-year and 20-year canopy goals .................................................................................................................... 66
Figure 28. Map displaying the Possible Planting Area by Community Planning Area and an … ........................ 67
Figure 29. Map displaying the Census Block Groups most suitable for trees due to high possibl e…area . 69
Figure 30. Map displaying the Census Block Groups with the lowest existing tree canopy cover ................. 70
Figure 31. Map displaying Census Block Groups most suitable for tree plantings to address …runoff ............ 71
Figure 32. Map displaying higher concentrations of minority populations for increasing tree…cover ......... 72
Figure 33. Map displaying Census Block Groups with underserved populations for increasing…canopy. . 73
Figure 34. Examples of the types of tree pruning ................................................................................................................................. 82
Figure 35. Types of pruning cuts and the proper branch cutting technique .................................................................. 82
Figure 36. Example of trees directionally pruned for clea rance from power lines ..................................................... 83
Figure 37. Example of branches to be pruned for newly planted trees to promote good structure ............. 84
Figure 38. Renton's Urban Forest Management Plan project website (RentonForestryPlan.com) ................. 93
Figure 39. Infographic summarizing the first public surve y ......................................................................................................... 94
Figure 40. Infographic summarizing the second public survey ................................................................................................ 94
Figure 41. Story maps can visualize urban forest stories, maps, and data for the public ........................................ 97
Figure 42. Example of the plan implementation, evaluation , and revision process ................................................... 111
Figure 43. Proposed decision matrix for tree and construction conflicts .............................................................................. F
Figure 44. Example of alternative solutions for tree and construction conflicts ............................................................. O
Tables and FIgures iv | P a g e
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Renton, WA Urban Forest Management Plan 10-year Update Jan2022 0 | P a g e
DEFINING THE URBAN FOREST
"Urban forestry can be defined as the art, science, and technology of managing trees and
forest resources in and around community ecosystems for the physiological, sociological,
economic, and aesthetic benefits trees provide to society." Helms, 1998
Any inhabited area that has trees and vegetation is considered an urban forest. Renton’s Urban
Forest Management Plan focuses on the City-owned trees in public rights-of-way, natural areas,
and parks, but also has implications for the trees on private property and attention to these are
addressed through community outreach and education efforts.
The concept of urban and community forest management developed in the 1960s out of the
death and devastation of the elm tree population throughout the United States due to Dutch
Elm disease. The discipline of urban forestry strongly advocates for species and age diversity in
a city’s tree population so that the elm tree devastation of the 1960s does not happen again.
Unfortunately, native and invasive pests and diseases continue to spread. During the last three
decades, urban forestry has evolved as researchers and practitioners learn more about the
structure and function of trees and their unique role in providing environmental, economic, and
social benefits to urban areas.
Urban forestry provides each of these benefits in differing circumstances as infrastructure, as
part of design and development, and as efficient and productive providers of economic
development. In fact, there are very few areas of urban management and its various
departments that aren’t affected and benefited by the urban forest.
Residents traditionally have indicated that they consider the trees in the community a priority.
In urban environments, street and park trees are sometimes the only day-to-day interaction
with nature that many residents may enjoy. As Renton continues to grow, the urban forest
needs a strong advocate. This will happen with the education and support of the City’s
constituency, staff, and elected officials via an approved Urban Forest Management Plan. The
urban forest is unique in the array of benefits it provides to the community, and a plan will
effectively collect and showcase these values.
While a plan is useful in helping educate and ensure future viability, it also will set up useful
parameters for the daily operations and care of the urban forest. A fresh look at all urban
forestry-related policies currently in place will bring into focus what is necessary for day-to-day
activities to ensure long-term viability and safety of the urban forest.
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Defining the Urban Forest 2 | P a g e
URBAN
FOREST
MANAGEMENT
PLAN
EXECUTIVE
SUMMARY
Renton, WA Urban Forest Management Plan 10-year Update Jan2022 I | P a g e
EXECUTIVE SUMMARY
The City of Renton is dedicated to building a thriving urban forest for a healthy and vibrant
place to live, work, and play. The nearly 117,000 City street, park, and natural area trees
throughout Renton are an asset that bring value and benefits to the community. Furthermore,
trees on private property provide added benefits. Together, these public and private trees
constitute an “urban forest”. This resource provides environmental benefits, adds to property
values, and contributes to an enhanced quality of life for all of Renton’s residents.
Realizing the urban forest is a valued asset, the City of Renton’s Community Services
Department at the time, led by the Urban Forestry & Natural Resources team, invested in a
collaborative planning process to update its 2009 Urban Forest Management Plan to provide
the framework for the Urban Forestry Program over the next 10 years. This Plan will serve as a
road map to support the long-term dedication to maintain and enhance the urban forest. The
Plan will provide an integrated approach to preserving, sustaining, diversifying, and
regenerating Renton’s urban forest into the future. By conducting an in-depth review of existing
City codes, policies, and plans regarding the urban forest as well as gathering input from the
community, the goals, objectives, strategies, actions, and monitoring techniques will be
developed for urban forest management Citywide. Participation from the community is
instrumental to the development of this Plan.
This forward-looking plan provides mission and vision statements, goals, and objectives. It
builds upon foundations in the Renton Comprehensive Plan, the Parks, Recreation and Natural
Areas Plan, Business Plans, and neighborhood plans. The aim is to ensure the safety, well-being,
and economic future of Renton’s citizens, as well as preserving the sustainability of the urban
forest. The Urban Forest Management Plan proposes steps to protect trees, forestry assets
(which are actual City assets), and the health of Renton’s citizens through urban forestry
services. Criteria for prioritizing resources to achieve best value and best management practice
have been used in the development of the listed improvements with short-term, medium-term,
and long-term timeframes. For Renton to remain “ahead of the curve” the City must proactively
engage in planning for regular planting of new trees and maintaining existing trees that is
guided by the urban forest vision and tree canopy cover goals. The City of Renton Urban Forestry
Program is dedicated to this vital resource and implementation of the Urban Forest
Management Plan in an effort to sustain and enhance it for all neighborhoods and future
generations.
Planning Approach II | P a g e
PLANNING APPROACH
The purpose of the 10-year Urban Forest Management Plan is to answer the fundamental
components of adaptive management: what do we have, what do we want, how do we get
what we want, and how are we doing. Developing the Plan required input from City staff,
stakeholders, residents, data sources, thoughtful analysis, a coordinated vision, and time.
What do we have?
The first step of the process is to
complete a baseline assessment of the
urban forest, the resources to manage it,
and the people that influence and
benefit from it. The six elements
completed in planning process provide
the foundation for setting goals and
measuring progress.
What do we want?
The Plan is shaped by knowing what the
urban forest needs, the resources required
to manage it, and what the community
wants. This was informed by public
engagement through websites and social
media, public surveys, presentations, staff
interviews, and development of the urban
forest vision and supporting goals.
How to get what we want?
The goal, action, and target framework lay
out the road map to achieve a shared
vision that supports the needs of all
members of the community. Actions are
strategic, measurable, attainable, realistic,
and time-bound (SMART) and have been
developed through extensive research,
data analyses, stakeholder consultations,
community engagement, benchmarking
research, and gap analyses during the
planning process.
How are we doing?
The City needs to continually monitor
progress towards the vision and goals.
The Urban Forest Management Plan
includes guidance for implementing
actions. The planning approach for this
Plan provides the framework for
continual monitoring and evaluation of
efforts using the U.S. Forest Service’s
Urban Forest Audit System. Updates to
this audit will inform any necessary
changes to strategies in an adaptive
management approach.
Renton, WA Urban Forest Management Plan 10-year Update Jan2022 III | P a g e
KEY FINDINGS
STATE OF THE URBAN FOREST
❖ 27,456 public street, park, or Maplewood Golf Course trees
❖ 89,528 natural area trees
❖ 116,984 total public trees
❖ 29.3% canopy (up 0.6% from 2010)
❖ Tree Equity Score of 83 out of 100
❖ 90 unique genera, Acer most common (27%)
❖ 281 unique species, bigleaf maple most common (15%)
❖ Public trees provide $220,000 in annual ecosystem benefits and services
❖ Public trees have a replacement value of $122.6 million
THE URBAN FORESTRY PROGRAM
❖ Parks and Recreation Department’s Parks Planning and Natural Resources Division
❖ 2.50 full-time employees (2021)
❖ 48% of public trees are in fair condition (2021)
❖ 22% of street trees need clearance pruning, 19% need structural pruning (2021)
❖ $8.13 budget per public tree (2021)
❖ 1.15 public trees per capita (2021)
❖ Urban Forest Audit: 65% overall
❖ Challenges include sustainable management, program efficiencies, risk tree
management, and tree policies/regulations/enforcement
❖ A 7-year pruning cycle requires 3,922 trees pruned per year at a cost of approximately
$706,011 annually
❖ Initial cost of an in-house arborist crew and fleet is $581,780 with an annual cost of
$270,698
❖ Tree Planting Initiative recommends 30% canopy by 2032 (5,250 total trees) and 33% by
2042 (18,852 total trees). 60% of plantings should be City-led or approximately 315 trees
per year for the 30% canopy goal and 570 trees per year for the 33% canopy goal.
COMMUNITY VIEWPOINTS AND PRIORITIES
❖ 38% feel the health of the urban forest has declined in the last 10 years
❖ 44% support increasing overall funding to the Urban Forestry Program for tree planting
and maintenance initiatives
❖ 8% support increasing the funding to the Urban Forestry Program for tree planting and
maintenance initiatives by redistributing the current program funding
❖ 47% support the additional funding be used for proactive street tree pruning
Key Findings IV | P a g e
URBAN FOREST MANAGEMENT GOALS AND OBJECTIVES
GOAL 1: Proactively manage public trees,
continue to grow and expand a healthy
canopy, maintain public safety, and
optimize urban forest benefits.
Objectives
1.1 Make data-driven management
decisions.
1.2 Sustainably manage the public tree
population.
1.3 Establish a strategy for increasing tree
canopy cover through City and public
efforts.
1.4 Effectively manage tree risk.
GOAL 2: Achieve environmental justice
through a partnership with the City and its
residents to improve well-being, human
health, local economies, and urban forest
sustainability.
Objectives
2.1 Create an urban forestry public
outreach program that addresses all
communities.
2.2 Increase capacity through trained
citizens.
GOAL 3: Strengthen policies for preserving
the environmental benefits, management,
and the character of Renton's urban forest.
Objectives
3.1 Strengthen policies for protecting the
urban forest.
3.2 Improve workflows and operations for
sustainable urban forest management.
Renton, WA Urban Forest Management Plan 10-year Update Jan2022 V | P a g e
URBAN FOREST MANAGEMENT PLAN FRAMEWORK
VISION
Renton’s urban and community
forest will be healthy, diverse, and
sustainable, reinforcing the City’s
strong commitment to community
trees. This strong commitment to
trees will benefit the well-being of
Renton’s residents and set an
example for other Urban Forestry
programs in the region.
GUIDING PRINCIPLES
❖ Recognize that the trees of the urban
forest are more than aesthetic
enhancements.
❖ Recognize trees as the backbone of the
urban ecosystem and an essential part
of the community’s green
infrastructure.
❖ Promote the health and growth of the
urban forest by following scientifically
established best management
practices for tree selection, planting,
watering, and pruning.
❖ Promote a robust urban forest through
policies and practices that reduce its
vulnerability to known diseases or pest
infestations, and future threats,
including the anticipated effects of
climate change.
❖ Engage in a continuous process of long-
range planning for the growth and
maintenance of the urban forest.
❖ Promote public appreciation of the
urban forest through educational
outreach programs.
❖ Support local businesses, institutions,
organizations, and individuals in their
efforts to grow and maintain the urban
forest through community education.
❖ Proceed in a manner that is inclusive
and transparent.
Call to Action VI | P a g e
CALL TO ACTION
The urban forest is an important green infrastructure asset for neighborhoods across Renton.
However, the capacity of urban forests to support healthy and resilient communities is
constrained and challenged by stressors such as climate change impacts, urban development
pressures, altered soils, invasive species, and resource shortages. Now more than ever there is a
critical need to sustain large, healthy, genetically appropriate trees and shrubs on public and
private land through long-term planning and budgeting, inclusive decision-making, and
strategic policy development that supports adaptive management. Thus, comprehensive urban
forest support must extend well beyond tree planting initiatives.
Management of Renton’s urban forest should be a shared priority among its citizens,
community groups, institutions, and City departments. All of these groups have important roles
to play. Successful management frameworks must recognize that the urban forest is part of a
complex system that includes the built environment and is influenced by human activities and
policies and practices that shape Renton. Furthermore, decision-making must be made in the
context of future uncertainty associated with climate change. With this understanding, along
with the input from staff and residents of Renton, the following priority strategies for
implementing the City’s Urban Forest Management Plan were developed:
KEY STRATEGIES
The planning process identified 22 strategies following development of the program goals and
objectives. Five strategies were identified as being of higher priority that will position Renton as
a leader in urban forestry across the state and perhaps the nation and will guid e the City
towards a sustainable urban forest than others.
7-Year Pruning Cycle Program
One of the more critical strategies identified was the need for an improved public tree pruning
program on a recommended 7-year rotation. The strategy requires additional funding and the
creation of an in-house arborist crew. Feedback from the community and City staff expressed
support for the structure of this strategy.
Tree Planting Initiative
To grow an urban forest that is sustainable and resilient to climate change, pests and diseases,
and urban development pressures, a strategic planting initiative guided by short- and long-term
canopy goals and planting targets are needed. The Plan contains the guidance for finalizing
canopy goals, identifying priority planting areas, and developing the tree planting initiative.
Tree Stewards Program
A shared commitment to the urban forest and vision is essential to the long-term success and
impact of the Plan. A community of tree stewards will increase Urban Forestry Program capacity
and support the Tree Planting Initiative along with other programs and services.
No-Net-Loss
Perhaps more important than tree canopy cover goals and planting initiatives is the foundation
of sound policies to preserve the existing urban forest. With this key strategy, tree replacement,
retention, removal, mitigation, and enforcement protocols are solidified. In addition, alternative
solutions to tree and sidewalk conflicts are explored and guidance for formally adopting a
decision checklist and solutions toolkit is provided.
Enforce Tree Regulations
Throughout the planning effort, concerns were expressed and identified relating to the
protection of trees from construction damage, illegal removals, maintenance malpractice. The
actions supporting this strategy expand the enforcement efforts by increasing capacity as well
as community education to prevent instances from occurring in the first place.
Renton, WA Urban Forest Management Plan 10-year Update Jan2022 VII | P a g e
RENTON’S URBAN FOREST MANAGEMENT PLAN
-2022-2032-
VISION
Renton’s urban and community forest will be healthy, diverse, and sustainable,
reinforcing the City’s strong commitment to community trees. This strong
commitment to trees will benefit the well-being of Renton’s residents and set an
example for other Urban Forestry programs in the region.
MISSION
The City of Renton will grow a thriving urban forest through strategic management,
diverse partnerships, and a strong commitment to protect and enhance the
community’s natural resources.
Renton, WA Urban Forest Management Plan 10-year Update Jan2022 1 | P a g e
PLAN PURPOSE AND FRAMEWORK
The main tenets of this Plan focus on ensuring public
safety, increasing operational efficiencies, facilitating
short- and long-term sustainable urban forest planning,
validating budgets and programs, ensuring equitable
distribution of green resources and services, and
standardizing methodology for asset management of the
urban forest.
The planning process consisted of two phases; the needs
assessment conducted as part of the planning process
and the development of goals, objectives, and strategies
in the Urban Forest Management Plan. The first phase
establishes a baseline from which short- and long-term
strategies can be developed and monitored over time.
The needs of the urban forest and the programs that
manage it were evaluated through an audit of existing
conditions and operations to establish a baseline for
measuring progress. This diligent approach to Renton’s
urban forest management gauges the City’s readiness
and available resources to achieve optimal levels of urban
forest management and sustainability. Through this
iterative approach, a comprehensive understanding was
gathered of the urban forest, the programs that manage
it, and the community that benefits from and shapes it to
inform strategic goals and actions.
In adhering to best management practice as framed by
the eight guiding principles listed on page ‘V’, the urban
forest stands a chance of being a sustainable and resilient
resource. This will require an integrated ecosystem
management approach. That system is based on the
recognition that the urban forest is a resource which
should be viewed as a tangible asset which confers broad
benefits to all citizens of the City of Renton and
compliments the biodiversity values of the surrounding
natural environment. Urban forests face unprecedented
challenges in a warming environment with ever
expanding development needs. In order to preserve the
urban forest and the myriad benefits conferred, the
residents of Renton will need to be vigilant and remain
committed to sound environmental standards which will
ensure that generations to come will enjoy the same. If
Renton is to be a leader and environmental champion,
the stewardship of its green infrastructure and the
fundamental role played by trees in that ecology is
paramount. This ten-year Urban Forest Management Plan
is an important piece of that larger mission. All
community stakeholders should be involved in bringing
this to fruition and safeguarding the future of trees in our
neighborhoods.
Plan Purpose and Framework 2 | P a g e
PLANNING APPROACH
The systematic evaluation of the City of Renton’s urban forest management processes,
resources, staffing, structure, and policies was conducted by completing the six planning
elements: 1) Existing Policies and Plans, 2) City Workflows and Operations, 3) Baseline
Conditions, 4) Urban Forest Benchmarks, 5) Community Engagement, and 6) Urban Forest Audit
System. The City’s project team evaluated the outcomes and findings of these planning
elements and the urban forestry consultants revised these based on feedback to provide a
comprehensive analysis that informs the baseline assessment and recommendations for the
Urban Forest Management Plan.
Figure 1. Framework of the Urban Forest Management Plan
PLANNING
ELEMENTS
PRIMARY PLANNING
FRAMEWORK OUTCOMES
EXISTING POLICIES
AND PLANS
GOALS
CITY WORKFLOWS
AND OPERATIONS
BASELINE
CONDITIONS
OBJECTIVES
URBAN FOREST
BENCHMARKS
COMMUNITY
ENGAGEMENT
STRATEGIES
URBAN FOREST AUDIT
SYSTEM
PRIMARY FRAMEWORK
Understanding the benefits and functions of the urban forest, the City has developed this Urban
Forest Management Plan.
“Without a plan, the governments and individuals responsible for taking care
of an urban forest will not be effective in meeting the tru e needs of the trees
and the community. A plan establishes a clear set of priorities and objectives
related to the goal of maintaining a productive and beneficial community
forest.” │ American Public Works Association, 2007
The optimal approach to managing an urban forest is to develop an organized, proactive
program using information to set goals and measure progress. This information can be utilized
to establish priorities, plan strategically, draft cost-effective budgets, and ultimately minimize
the need for costly, reactive solutions to crises or urgent risk mitigation. Based on the results of
the research, incremental steps to achieve these improvements were developed that can be
applied as the City continues to progress.
ACHIEVE
THE
URBAN
FOREST
VISION
Renton, WA Urban Forest Management Plan 10-year Update Jan2022 3 | P a g e
The goals of the Urban Forest Management Plan focus on preserving, maintaining, and
enhancing the urban forest to ultimately benefit the residents of Renton. The framework for
this Plan supports the urban forestry vision:
Renton’s urban and community forest will be healthy, diverse, and sustainable, reinforcing
the City’s strong commitment to community trees. This strong commitment to trees will
benefit the well-being of Renton’s residents and set an example for other Urban Forestry
programs in the region.
Goals
Goals supporting the urban forest vision are provided based on strengths and opportunities
identified during the planning process. Each goal is supported by objectives and strategies the
City and partners will use to attain the goal.
Objectives
Objectives define the steps to attain the identified goals.
Strategies
Strategies and actions are specific, measurable, attainable, realistic, and time-bound.
Recommendations
As information and findings are detailed in each of the Plan’s sections, a discussion of
recommendations is included to support the goals, objectives, and strategies.
Evaluation
Using the Urban Forest Audit System and the Implementation Schedule, progress and success
can be evaluated and annually reported. The evaluation using the audit provides the
information necessary for adaptive management.
Introduction 4 | P a g e
INTRODUCTION
A healthy urban forest supports the City of Renton’s goals of balancing economic vitality with
environmental equity and social well-being by enhancing public green space, increasing city
attractiveness and livability, and fostering civic pride. Studies show that trees and other
vegetation filter pollutants, increase property values, attract visitors, improve health and
promote community unity through events like Arbor Day.
The Renton Urban Forest Management Plan (“Plan”) update is the collaborative effort from City
departments to create a proactive work plan that guides the City’s urban forestry and natural
resource management programs. This Plan builds upon existing programs and establishes the
focus and direction for the next 10 years.
The state of Renton’s urban forest, from the downtown core to new and existing commercial and
residential districts, has been reviewed. Interaction between different City departments in
recent years was key to developing appropriate strategies to incorporate the varied priorities
affected by trees in the urban landscape. Nearly all departments in the City interact with the
Urban Forestry Program, benefit from the urban forest, or are impacted in some way.
To ensure the program’s vision and mission statements, various issues and opportunities were
reviewed— from public safety to current tree regulations— to accurately capture public concerns
with trees and vegetation.
The intention of this Plan is to create a road map for the future of the Urban Forestry Program.
The previous plan suggested creating an Inter-departmental Team over the course of the 10-year
plan. This was never implemented. To realize the maximum benefits afforded by the urban forest
and make the community a great place to live, work and play, a more consistent approach is
needed.
There is a need for continued work on the forestry ordinance. The Plan proposes a new Tree
Planting Initiative (TPI) to be more proactive and equitable about replacing trees that are lost
and to preserve and enhance tree canopy cover equitably. Best management practices also
point to the need for a Tree Risk Plan (TRP) and ideally an in-house arborist crew.
Although the urban forest provides a broad range of ecosystem services— direct and indirect
benefits provided to the City, its citizens, the region, and the planet— we tend to take the
benefits for granted because they are not assigned a dollar value. That is changing and many of
the benefits are not only tangible but measurable. Local cities, state, and national sources
continue to increasingly find great value in urban forests.
Unfortunately, these green assets are often overlooked in the land development process and
destroyed for a fraction of their larger economic and ecosystem values. It is critical to bear in
mind that long-term management of these natural assets brings a higher return than their
elimination or the upfront maintenance costs. The fact is that trees — “green infrastructure”—
increase in value over time, unlike gray infrastructure like roads, poles, pipes, and sidewalks.
Figure 2 below begins to highlight the benefits of trees in communities, emphasizing the role
they play in maintaining community health, well-being, safety, environments, and local
economies.
Renton, WA Urban Forest Management Plan 10-year Update Jan2022 5 | P a g e
BENEFITS OF THE URBAN FOREST
The quality of life of the citizens in any community depends on the urban forest, as trees make
a vital and affordable contribution to the sense of community, pedestrian-friendly
neighborhoods, energy savings, and air quality. Trees are one of the few infrastructure
investments that grow in value over time.
Tree canopy is a valuable component of Renton’s urban ecosystem. Trees in urban settings are
important to improving urban life, as well as human physical and emotional well -being.
Research suggests that human beings have an innate affiliation to natural settings, a concept
described as biophilia (Kellert and Wilson 1993). Studies link access to living trees, outdoor air,
and natural light to increased employee and student productivity, faster hospital recoveries, less
crime, and an overall reduction in stress and anxiety. Thus, expanding the urban forest is part of
the solution to Renton’s social, environmental, and economic problems— it is integral to
enhancing public health programs, increasing land values and local tax bases, providing job
training and employment opportunities, reducing costs of city services, increasing public safety,
improving air quality, offsetting carbon emissions, managing stormwater runoff, mitigating
water shortages, and conserving energy. The following data was derived from Alliance for
Community Trees.1
11 Alliance for Community Trees. 2011. Benefits of trees and urban forests: A research list. www.actrees.org
Figure 2. Overview of the ecosystem benefits and services provided by trees in communities (Source: City of Renton)
Benefits of the Urban Forest 6 | P a g e
REDUCE STRESS AND IMPROVE THE QUALITY OF LIFE
Neighborhoods with generous canopies of trees are good for public health.
Greater contact with natural environments correlates with lower levels of stress,
improving performance. Students’ concentration levels go up when they are able
to look out onto a green landscape. Studies show that children with attention
deficit disorder function better after activities in green settings. A green
environment impacts worker productivity. Workers without views of nature from
their desks claimed 23% more sick days than workers with views of nature.
Residents of areas with the highest levels of greenery were 3 times as likely to be
physically active and 40% less likely to be overweight than residents living in the
least green settings.
CLEAN THE AIR AND BREATHE EASIER
Shade trees reduce pollution and return oxygen to the atmosphere. In addition
to carbon dioxide, trees’ leaves or needles absorb pollutants, such as ozone,
nitrogen dioxide, sulfur dioxide, and some particulate matter.
SAVE ENERGY AND LOWER ENERGY COSTS FOR BUILDINGS
As natural screens, trees can insulate homes and businesses from extreme
temperatures, keep properties cool, and reduce air conditioning utility bills . A
20% canopy of deciduous trees over a house results in annual cooling savings of
8 to 18 percent and annual heating savings of 2 to 8 percent. By planting shade
trees on sunny exposures, residents and businesses can save up to 50% on hot-
day energy bills.
POSITIVELY INFLUENCE CLIMATE TO ENSURE SUSTAINABILITY
Trees absorb carbon dioxide and store carbon in wood, which helps to reduce
greenhouse gases. Carbon emissions from vehicles, industries, and power plants
are a primary contributor to increased air temperatures in metropolitan areas.
Trees in the United States store 700 million tons of carbon valued at $14 billion
with an annual carbon sequestration rate of 22.8 million tons per year valued at
$460 million annually.
REDUCE THE NEED FOR STREET MAINTENANCE
Shaded streets last longer and require far less pavement maintenance, reducing
long- term costs. Canopy diminishes pavement fatigue, cracking, rutting, and
other damage. A study from University of California at Davis found that 20%
shade cover on a street improves pavement condition by 11%, which is a 60%
savings for resurfacing over 30 years.
Renton, WA Urban Forest Management Plan 10-year Update Jan2022 7 | P a g e
RAISE PROPERTY VALUES
Trees are sound investments, for businesses and residents alike, and their value
increases as they grow. Sustainable landscapes can increase property values up to
37%. The value of trees appreciates over time, because the benefits grow as they
do. For businesses, trees have added value, including higher revenues. Shoppers
seek out leafy promenades that frame storefronts. Research shows that shoppers
spend more—between 9 and 12 percent more—on products in tree-lined business
districts. A study by Donovan & Butry in 2008 shows trees increase value to the
home they reside but also contribute to increased property values of adjacent
homes and properties. As an additional benefit, increased property values
resulting from trees lead to quicker home sales (Wolf 2007).
CONSERVE WATER AND SOIL
A tree’s fibrous roots, extending into the soil, are premier pollution filtration and
soil erosion prevention systems. Intensely urbanized areas are covered with a large
number of impermeable surfaces. In contrast to an impervious hardscape, a
healthy urban forest can reduce annual stormwater runoff up to 7%. Highly
efficient trees also utilize or absorb toxic substances such as lead, zinc, copper, and
biological contaminants. One study estimated that eliminating the need for
additional local stormwater filtration systems would result in savings exceeding
$2 billion.
COOLER PAVEMENT DIMINISHES URBAN HEAT ISLANDS
Broad canopy trees lower temperatures by shading buildings, asphalt, and
concrete. They deflect radiation from the sun and release moisture into the air.
The urban heat island effect is the resulting higher temperature of areas
dominated by buildings, roads, and sidewalks. Cities are often 5° to 10°F hotter
than undeveloped areas, because hot pavement and buildings have replaced cool
vegetated land. In addition, high temperatures increase the volatility of
automobile oil and oil within the asphalt itself, releasing the fumes into the
atmosphere. Shade trees can reduce asphalt temperatures by as much as 36°F,
which diminishes the fumes and improves air quality.
PROTECT WILDLIFE AND RESTORE ECOSYSTEMS
Planting and protecting trees can provide habitat for hundreds of birds and small
animals. Urbanization and the destruction of valuable ecosystems have led to the
decline of many of species. Adding trees, particularly native trees, provides
valuable habitat for wildlife.
Figure 3. The street tree pictured adds $7,593
to the price of the house it fronts and $7,098
to the seven houses within 100 feet, giving a
total value of $14,691. The dotted line
represents the tree’s 100-ft radius sphere of
influence. (Donovan & Butry, 2008)
Benefits of the Urban Forest 8 | P a g e
BUILD SAFE COMMUNITIES AND DECREASE CRIME
Police and crime prevention experts agree that trees and landscaping cut the
incidence of theft, vandalism, and violence by enhancing neighborhoods. Thriving
trees on well-maintained streets indicate pride of ownership. Public housing
residents with nearby trees and natural landscapes reported 25% fewer acts of
domestic aggression and violence. Apartment buildings with high levels of
greenery had 52% fewer crimes than those without any trees. Buildings with
medium amounts of greenery had 42% fewer crimes.
CALM TRAFFIC AND MAKE NEIGHBORHOODS SAFER AND QUIETER
People drive more slowly and carefully through tree-lined streets, because trees
create the illusion of narrower streets. One study found a 46% decrease in crash
rates across urban arterial and highway sites after landscape improvements were
installed. The presence of trees in a suburban landscape reduced the cruising
speed of drivers by an average of 3 miles per hour. Faster drivers and slower drivers
both drove at decreased speeds in the presence of trees. Trees reduce noise
pollution, buffering as much as half of urban noise. By absorbing sounds, a belt of
trees 100 feet wide and 50 feet tall can reduce highway noise by 6 to 10 decibels.
Buffers composed of trees and shrubs can reduce 50% of noise.
A comprehensive analysis of the ecosystem services and benefits provided by the trees
inventoried in 2020 are provided in the Value and Benefits of the Public Tree Population section.
Renton, WA Urban Forest Management Plan 10-year Update Jan2022 9 | P a g e
HISTORICAL BACKGROUND
First was the Forest. The Duwamish were the first people known to inhabit the present-day
location of the City of Renton. At that time, dense stands of old -growth trees, including Douglas
fir, western red cedar, and western hemlock, blanketed the hills above fertile river valleys. The
land was abundant with natural resources. Trees were harvested in limited quantities to build
longhouses and large dugout canoes.
Lumber and Coal Harvesting. Renton’s first white settler, Henry Tobin, came to this area in 1853
with business interests in lumber. After his neighbor discovered coal the following year, Tobin,
Dr. R.H. Bigelow, and two other early settlers formed the Duwamish Coal Company and built a
sawmill at the junction of the Cedar and Black Rivers. Timber from the mill was used to shore
up coal-mine tunnels. The mill burned during the Indian War of 1855, temporarily halting
mining operations. More white settlers arrived in the 1860s and began clearing trees, often by
burning, to open land for farming and dairy. New coal seams were discovered in outlying areas
and Renton’s rivers provided important shipping connections from Lake Washington to Seattle
and beyond. The small settlement near the lake became an important stopover for lodging,
food, and supplies. Significant coal discoveries in Renton in the 1870s changed the farming
community into a rugged mining town. Active logging operations resumed with the opening
of the Parker sawmill. The timber was again used to support mine shafts, but also to construct
homes and businesses.
The City of Renton is Born. Erasmus Smithers filed the first square-mile plat of the town of
Renton in 1875. The town was named in honor of Captain William Renton, the most successful
lumber merchant of the time who heavily financed Renton’s early coal industry. The City of
Renton incorporated in 1901 with a population of approximately 1,300.
Additional transportation improvements and industrial establishments spurred growth
throughout the 20th century. The most dramatic growth period occurred with the influx of
wartime industry workers at Boeing and PACCAR between 1940 and 1950, when the population
rose from 4,500 to over 16,000. Forest clearing continued to make way for the airport, industrial
areas, commercial centers, and housing.
Urban Forestry’s Early Beginnings in Renton. Early urban forestry in Renton included tree
planting funded by various federal grants and maintained by the Public Works Department. No
formal maintenance program was in place during the years prior to 1980. Trees were managed
and maintained on a reactive, emergency basis. During the early 1980s a Street Tree Committee
was formed to address many urban tree issues. They offered recommendations to City Council
and developed regulations for planting and maintaining trees. Mature trees in the downtown
business district growing in small sidewalk cut-outs resulted in damage to the sidewalks. A
street tree ordinance was drafted but never adopted.
In 1982, Renton’s Parks Department took over responsibility for trees in the downtown area from
Public Works. The Parks Department spearheaded and established a routine vegetation
management program that included improved standards for evaluations, street tree pruning,
removals, and replacements.
In the 1980s and 1990s, tree maintenance reverted to the improper practice of rounding -over
trees (a form of topping) to keep large-maturing sizes in scale with buildings and overhangs.
Tree removal and sidewalk replacement was an expensive result of trees that became too large
in limited planting spaces. Unregulated tree planting in neighborhoods was customary.
Residential streets, planted mainly with ornamental cherry and purple leaf plum trees, were
eventually topped by residents. Public Works struggled with the resulting “bushy” trees. Street
sweeping proved difficult and both vehicles and trees were needlessly damaged. Public safety
was also being compromised by trees blocking streetlights. The conflict between nature and
Historical Background 10 | P a g e
civilization was apparent. Nearly every City department and many residents were affected by a
lack of proper tree planning and design during this period and struggled to find an effective
solution to public safety issues.
In the 1990s, the City’s aggressive program of acquiring additional natural areas provided
important watershed and wildlife habitat. However, development pressures resulted in
encroachments, unauthorized use, and trash disposal by both private residents and developers
within natural areas. Besides topping in such areas, whole tree removal was occurring without
City authorization. Natural area lands were being partially occupied by a few residents, mostly
because they were not aware of property line locations. Discarded yard waste and house plants
contributed to the establishment of invasive plants such as ivy.
Urban Forestry Awakening During the 1990s. In 1992, a tree ordinance was again proposed but
was never brought to City Council for adoption and never resurrected again. The problems that
had been occurring with trees in the built environment, the lack of good design standards and
unregulated maintenance continued unabated.
Protecting the public has been a paramount concern of City departments despite some of the
controversy that has ensued. It often takes an incident to occur before a hazard is recognized.
In 1997, 65 mature bigleaf maples along Maple Valley Highway were removed by the City after
several tree limbs fell, temporarily closing the highway and the Maplewood Golf Course main
entrance.
After careful assessment of their condition, it was determined that the maples posed a
significant risk to public safety. While there was public outcry at their removal, many local
residents praised the City for being proactive.
In 1998, a Beautification Program was adopted by City Council. City leaders recognized that
trees were an important and integral part of the community consistent with City goals. The plan
included urban forestry components such as a tree ordinance (not completed), public
education and awareness, a tree inventory, a tree management policy, an adopt -a-park
program, marketing plan, and a method for measuring performance.
The 21st Century. By 2000, the City of Renton’s population grew to 50,052 and to over 80,000
in 2009. Through a series of annexations, Renton’s boundaries have expanded to 22.3 square-
miles. Rapid development has replaced the old growth forests of the past. Subsequently, an
awareness of the pace of development, loss of City trees, salmon recovery, and better water
quality both locally and regionally have driven an interest in urban forest conservation,
enhancement, and programming. Tree maintenance continued to be shared by Public Works
and the Community Services Departments. Public Works regularly maintained trees in
neighborhoods where branches interfered with sweeper trucks during the winter.
Otherwise, most of the street trees were maintained by Public Works crews on a reactive basis
following calls or complaints. Community Services crews provided more frequent maintenance
of trees in the downtown core, collaborating with Public Works on tree and sidewalk conflicts
and tree plantings in sidewalk openings. Storm damage to trees was coordinated citywide by
the Public Works Department with Community Services providing support. T ree maintenance
service contracts issued by the Community Services Department required tree work performed
by International Society of Arboriculture (ISA) Certified Arborists to assure proper maintenance
to City trees. The Beautification Program continued to move forward and in 2002 Renton’s first
City Forester was hired under the title, Parks Maintenance Manager, and worked in the
Community Services Department.
Renton, WA Urban Forest Management Plan 10-year Update Jan2022 11 | P a g e
2002 to 2009.
• Staff training in arboriculture and introduction to proper tree and vegetation
management to Community Services and Public Works staff. Elimination of all
rounding-over (topping) of public trees.
• Cooperative partnerships with Puget Sound Energy (PSE) to reduce tree and electric
wire conflicts. On Park Avenue, ash trees were removed by PSE and PSE donated “wire-
friendly” trees.
• In 2003, the City’s began inventorying its public trees.
• Eliminated planting large maturing trees in small sidewalk cut-out sections. Utilizing
larger 4 x 8 foot cut-out sections and planting smaller-maturing trees.
• Completed a city-wide tree inventory and assessment for street trees, park trees and
trees in natural areas. Street trees and park trees were located using global positioning
satellite (GPS) coordinates and integrated into the City’s graphic information system
(GIS).
• Budgeting in the Capital Improvement Program for Forestry Program Development and
Tree Maintenance.
• Adopted Tree Retention [Protection] Regulations for new development.
• Renton’s first certified arborist trained in 2006 under the ISA certification program.
• Added tree-related policies to the City’s Comprehensive Plan that regulated street trees
along new or reconstructed streets and the landscape of new property developments.
• City staff from multiple departments met to form the Urban and Community Forest
Task Force, hired consultants and initiated the process for preparation of the Renton
Urban and Community Forestry Development Plan.
• Presentations to elected officials and organizations of the Renton Urban and
Community Forestry Development Plan.
Recognition. In 2008, for the first time, the City of Renton achieved Tree City USA status for
efforts in urban forestry programming. This award is given annually by the National Arbor Day
Foundation in cooperation with the National Association of State Foresters and the USDA Forest
Service. Renton can now place Tree City USA signs at community entrances to show visitors that
Renton cares about its environment and is dedicated to preserving a quality lifestyle. The annual
Tree City USA award presentation and Arbor Day celebration offer excellent publicity
opportunities—reaching large numbers of people with information about tree care and
conservation. Becoming a Tree City USA, Renton now qualifies to receive awards of state and
federal agency grants.
In 2009, the Maplewood Golf Course became Washington’s second municipal golf course to be
designated a “Certified Audubon Cooperative Sanctuary” by Audubon International.
Historical Background 12 | P a g e
2009 to Present.
• The City completed its first ever high-resolution urban tree canopy assessment in 2011
finding 28.6% of the City is covered by the canopy of trees when viewed from above.
• In 2018, the City updated its tree canopy assessment finding the urban forest covers 29.3%
of Renton— up 0.7% in six years (2011 and 2017 imagery used).
• The Urban Forest Inventory and Resource Analysis Summary Report was completed in
2021.
• This document updates the 10-year urban forest management plan through 2032.
• Renton has been a Tree City USA recipient for 14 years, including 11 Growth Awards in the
process.
Current State of Renton’s Urban Forest 13 | P a g e
CURRENT STATE OF RENTON’S URBAN FOREST
Urbanization creates significant changes in land use and land cover, affecting the structure,
pattern, and function of ecosystems. The public is increasingly concerned about how these
changes influence daily life and affect the sustainability of “quality of life” for future generations.
Improving air quality, cooling urban heat islands, reducing stormwater runoff, and building
resiliency against pests, diseases, climate change, and storm events are challenges facing the
City of Renton. Rapid growth in Renton, with a population of over 10 7 thousand people, is
accelerating these problems. The problems need solutions as the City tries to protect and
restore environmental quality while enhancing economic opportunity.
Renton is a vibrant city that will continue to grow. As it grows, it should also continue to invest
in its tree canopy. This is no easy task, given financial constraints and trends toward higher
density development that may put space for trees at a premium. The challenge ahead is to
better integrate the green infrastructure with the gray infrastructure by increasing tree planting,
providing adequate space for trees, and designing plantings to maximize net benefits over the
long term, thereby perpetuating a resource that is both functional and sustainable.
To make informed decisions about its tree canopy and the strategies to preserve and enhance
it, analyses of the urban forest were completed as part of the planning process. These analyses
look at the various types of landscapes that comprise the urban forest along with the ownership
type and the maintenance responsibility. These various landscapes are depicted in Figure 4 on
the following page.
The most extensive data on the Citywide urban forest was gathered from two urban tree canopy
assessments in 2011 and 2018. The Citywide urban forest is measured with these high-resolution
urban tree canopy (UTC) assessments using various imagery and GIS processes. The primary goal
of this type of assessment is to identify a baseline and benchmark of the City’s tree canopy and
analyze the land cover class across a range of geographic boundaries. This analysis identifies
areas for tree canopy preservation as well as the opportunities for new urban tree canopy cover.
A bottom-up assessment of Renton’s urban forest was also completed using the City’s updated
public tree inventory database. This dataset focuses on the trees that are the City’s responsibility
to maintain and are located along streetscapes within the public right -of-way, in public parks,
and on public properties. Based on these datasets, Renton has a total of 27,456 public trees
along streets, in parks, and in the Maplewood Golf Course, and a total of 89,528 trees in natural
areas.
Current State of Renton’s Urban Forest 14 | P a g e
THE URBAN FOREST EXTENT AND LANDSCAPES
CITYWIDE OPEN SPACE WATERWAYS
CAMPUSES PARKS YARDS
PRIVATE PROPERTY DOWNTOWN STREETS
Figure 4. Depiction of the various types of landscapes that comprise Renton's urban forest
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 15 | P a g e
URBAN TREE CANOPY COVER
The analysis of Renton’s urban forest begins at the
largest scale, the urban tree canopy cover. Renton’s
2018 Urban Tree Canopy Assessment utilized 2017
high-resolution imagery to evaluate the extent of and
opportunities for tree canopy cover. Currently, 29.3%
of the City’s land area is covered by the canopy of
trees across public and private boundaries. Another
way to look at the extent of this resource— of the
14,935 total land acres in Renton, 4,382 acres are
covered by tree canopy— equivalent to the area of
over 3,300 NFL-sized football fields.
The assessment also identified areas for potential
new tree canopy—tree planting—and a total of 20%
(3,030 acres) of Renton’s land area is either grass, low-
lying shrubs, or impervious surfaces.
Figure 6. Renton’s 2018 Tree
Canopy Assessment results
CITYWIDE
TREE CANOPY ASSESSMENT RESULTS
(2018)
STREETS, MEDIANS,
BACKUP LOTS, ALLEYS
City Maintained
or Other
PARKS, OPEN SPACE,
NATURAL AREAS
City
Maintained
PRIVATE
PROPERTY
Owner or Other
Maintained
PUBLIC TREES PRIVATE TREES
TREE MAINTENANCE RESPONSIBILITY
Figure 5. Maintenance responsibility of trees comprising Renton's urban forest
Existing
Tree
Canopy
Cover,
29%
Total
Possible
Planting
Area, 20%
Total
Unsuitable
Area, 50%
Current State of Renton’s Urban Forest 16 | P a g e
Tree Canopy
Possible Vegetative Planting Area
Possible Impervious Planting Area
Unsuitable Impervious
Water
Figure 7. Map displaying Renton's tree canopy and vegetative area for possible tree plantings (2018)
TREE CANOPY AND VEGETATIVE AREA FOR POSSIBLE TREE PLANTINGS (2018)
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 17 | P a g e
The tree canopy assessment was further analyzed to identify areas with more or less tree cover
and areas where there are potential opportunities for more canopy to exist. The charts below
summarize these metrics by Community Planning Areas and Zoning Type followed by analyses
of canopy cover change from 2010 to 2017.
EXISTING TREE CANOPY COVER (%) BY COMMUNITY PLANNING AREA
11%14%17%22%
32%
69%
0%
10%
20%
30%
40%
50%
60%
70%
80%
Center
Downtown
Center Village Industrial Commercial Residential Resource
Conservation
EXISTING TREE CANOPY COVER (%) BY ZONING TYPE
31%
47%
13%
29%
25%
34%
39%
29%31%
0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
50%
Figure 9. Existing tree canopy cover by Zoning Type (consolidated classifications)
Figure 8. Existing tree canopy cover by Community Planning Area
Current State of Renton’s Urban Forest 18 | P a g e
URBAN TREE CANOPY COVER CHANGE
+ 0.6%
4,200
4,250
4,300
4,350
4,400
AcresUTC 2010 (Acres)UTC 2017 (Acres)
+2.1%+2.5%+1.0%+2.1%+3.6%
-0.7%
-2.1%
0
500
1,000
1,500
2,000
2,500
3,000
AcresUTC 2010 (Acres)UTC 2017 (Acres)
TREE CANOPY CHANGE IN RENTON (2010-2017)
TREE CANOPY CHANGE BY COMMUNITY PLANNING AREAS (2010-2017)
TREE CANOPY CHANGE BY ZONING TYPE (2010-2017)
Figure 10. Citywide tree
canopy cover change
Figure 11. Tree canopy cover
change by Community
Planning Area
Figure 12. Tree canopy cover change by Zoning Type
(consolidated classifications)
-0.9%
-1.9%
+2.1%
-2.4%
+2.0%
+1.6%
-0.9%+4.2%
-0.2%
0
100
200
300
400
500
600
700
800
900
1,000
AcresUTC 2010 (Acres)UTC 2017 (Acres)
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 19 | P a g e
Results
The Citywide tree canopy cover based on 2017 imagery is 29.3% meaning of the 14,935 total land
acres in Renton, there are 4,382 acres covered by tree canopy when viewed from above. The
2018 assessment also identified possible planting areas, those areas that are grass and low-lying
shrubs and impervious areas such as parking lots that could theoretically be spaces for new
trees. The combination of these possible planting areas is referred to as Total Possible Planting
Area or Total PPA. Citywide, the Total PPA is comprised of 18% (2,714 acres) vegetative planting
area and 2% (316 acres) impervious planting area.
At a finer scale, tree canopy cover across Community Planning Areas varies between 13% in City
Center to 47% in Cedar River. Across Zoning Types, the tree canopy varies but resembles a
similar distribution among the types of zoning classes found in other community studies. For
example, the Resource Conservation Zoning Type has the highest amount of tree canopy cover
compared to its total land area with 69%. The Residential Zoning Type canopy cover is less than
half the amount of Resource Conservation but is the second highest of the Zoning Types with
32% tree canopy cover. It should be noted that while Residential has the second highest
percentage of tree canopy, it holds the highest amount of actual canopy cover acres with 2,510
acres of canopy whereas Resource Conservation has 863 acres of canopy cover.
When comparing canopy cover from the two assessments (2011 assessment using 2010 imagery
and 2018 assessment using 2017 imagery), it was found that the canopy cover Citywide has
increased by 0.6% in the seven-year timespan. This change from 28.7% in 2010 to 29.3% in 2017
was further analyzed by Community Planning Area, Zoning Type, and all other geographies
included in the study. Across the Community Planning Areas, the greatest amount of canopy
loss between the two time periods was experienced in East Plateau (2.4% decrease) and the
highest amount of canopy gain was observed in Valley (4.2% increase). Between 2010 and 2017,
City Center experienced a 2.1% growth in canopy. Observing canopy cover change across Zoning
Types, the greatest loss of canopy was observed in the Resource Conservation Zoning Type (2.1%
decrease) and the greatest increase in canopy was found in the Commercial Zoning Type (3.6%
increase).
Discussion/Recommendations
To inform localized urban forest management, the tree canopy metrics were summarized by
various planning boundaries including Land Use, Zoning Type, Community Planning Areas,
Watersheds, Census Block Groups, and Catchments. With finer scale analyses of the existing
tree canopy and possible planting area compared to historical cover amounts (2010) in
Community Planning Areas and Zoning Types, urban forest management strategies can be
developed to support the Plan’s vision. For example, the Commercial Zoning Type experienced
a 3.6% increase in tree canopy cover, likely due to planning and development requirements and
the City’s tree ordinance requiring tree preservation and planting. Also, the overall canopy cover
increase is largely attributable to the annexation of the Benson planning area.
Further analyses of existing canopy cover, possible planting space, tree equity (in the following
section), and factors influencing changes were conducted to inform the canopy cover goals
presented in the Tree Planting Initiative and Tree Canopy Cover Goals sections.
Comprehensive reports were prepared for the 2011 and 2018 tree canopy assessments where
additional details regarding canopy cover, possible planting space, canopy cover change, and
ecosystem benefits are provided.
Current State of Renton’s Urban Forest 20 | P a g e
URBAN TREE EQUITY
The surface temperatures during a heat wave can vary
dramatically by city and by neighborhood. A big reason for
the difference across city neighborhoods is shade and the
canopy of trees that line some sidewalks but not others.
Through analyses and local assessments, it is observed
that a city’s wealthier areas zoned for single-family homes
typically attract more city services, like wide sidewalks and
trees. As time progresses, that disparity becomes more
than a matter of aesthetics. Research shows shade and
water evaporation from trees can lower surrounding air
temperatures by six degrees or more. While it is well
known that shade from a tree can help keep the ground
temperatures cooler, as climate change continues to
affect the region, the stakes are likely to get higher. In
certain cases that shade could be the difference between
life and death, especially for the sick, elderly, and disabled
people. Studies show that just an extra degree during a
heat wave increase mortality 2-3 percent (Dr. Feinstein,
Sustainability and Resilience Policy Director, SPUR, 2021).
Many areas lack adequate tree canopy perhaps due to a
series of consecutive policies championed by local
authorities, codification through federal actions, and
decisions to disinvest in neighborhoods where people of
color resided as regions grew rapidly in population and
infrastructure. A pattern was created that is replete in the
urban studies literature (J. Wolch et al 2005).
Other possible factors may include the competition for
limited physical space, and the increasing dominance of private real estate in driving
development processes and occupying areas with pavement that might otherwise contain
green space.
Specifically in Renton, trees are generally sparse in socioeconomically disadvantaged areas and
more prominent in wealthier neighborhoods. The tree canopy and associated benefits of the
urban forest are not equally shared and experienced by all communities. Whatever the cause
for canopy disparity, the purpose of this tree equity study is to state the baseline conditions,
identify priorities, and establish goals for increasing tree canopy cover equitably while
overcoming and contending with urban planning and development, the effects of climate
change, exotic tree pests and diseases, limited resources, and other factors.
Focused on addressing this canopy cover inequity, the American Forests organization created
the Tree Equity Score (TES, TreeEquityScore.org) tool that measures tree equity across 150,000
U.S. neighborhoods and 486 municipalities in urban areas. Each community’s TES indicates
whether there are enough trees for everyone to experience the health, economic, and climate
benefits that trees provide. The scores are based on how much tree canopy and surface
temperature align with income, employment, race, age, and health factors. A 0- to-100-point
system makes it easy to understand how a community is doing. With the knowledge the score
provides, Renton’s community leaders, tree advocates, and residents alike can address climate
change and public health through the lens of social equity, attract new resources, factor the
scores into technical decisions, guide implementation of the 2022 Urban Forest Management
Plan, and track progress toward achieving tree equity. A score of 100 represents tree equity.
Figure 13. Example of canopy cover
differences in two Renton neighborhoods
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 21 | P a g e
Figure 14. Map displaying the Tree Equity Scores by Census Block Groups in Renton, WA (TreeEquityScore.org)
Tree Equity Scores
0 – 63
64 – 79
80 – 89
90 – 99
100
Census Block Groups
TREE EQUITY SCORES BY CENSUS BLOCK GROUPS (TREEEQUITYSCORE.ORG)
Current State of Renton’s Urban Forest 22 | P a g e
91 88 86 84 83 83 80 78 76 73
0
10
20
30
40
50
60
70
80
90
100
TREE EQUITY SCORE COMPARISONS
Figure 15. Comparison of Tree Equity Scores for cities near Renton, WA
9
23
16
19
6
0
5
10
15
20
25
100 90-99 80-89 64-79 0-63Count of Census Block GroupsTree Equity Score Ranges
DISTRIBUTION OF TREE EQUITY SCORES AMONG RENTON’S CENSUS BLOCK GROUPS
Figure 16. Count of Census Block Groups for each Tree Equity Score range
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 23 | P a g e
Results
Based on the criteria evaluated for each Census Block Group in Renton, the Citywide Tree Equity
Score is currently at a score of 83 out of 100. This score is based on a combination of metrics for
73 Census Block Groups (CBG) comprising the City (refer to Figure 14). Compared to nine other
cities in the region, Renton’s TES is slightly above the average of 81 but ranks fifth out of the ten
total cities used in the study. As shown in the previous figure (Figure 16), only nine of the CBGs
are attaining complete tree equity with a score of 100 and six CBGs have a TES less than 63. The
majority (23 or 31%) of CBGs have a TES between 90 and 99.
Discussion/Recommendations
In the past few years, regional partners are increasingly acknowledging and confronting the
past practices, current perceptions, and accelerating progress to ensure that communities,
landscapes, and policies are more intentional about enhancing historically disinvested areas.
Ambitious goals to increase tree canopy in areas of greatest need are drafted for the City’s
review and adoption. These goals will grow a more equitable urban forest that provides cooling,
public health, habitat, energy saving, and other benefits. In addition, the City should commit to
plant and maintain trees, update and align policies and procedures to grow and protect public
and private trees, and engage the citizens of Renton to become advocates and stewards of the
City’s urban forest.
Although the City will oversee and monitor these canopy goals, the effort will inevitably require
extensive support from all City departments, community-based organizations, and others
aiming to prepare for a changing climate. As a first step, this Plan provides guidance to prioritize
resilient, climate-appropriate trees, preserve and conserve mature trees, and properly manage
resources to ensure that trees thrive in the urban environment. The cooperation of the City,
partners, organizations, property owners, and others is instrumental to meeting these goals, and
the Tree Planting Initiative and Tree Canopy Cover Goals sections provide the approach to
formally establish a tree canopy goal that will guide this shared commitment.
A shared commitment to tree canopy cover and equity goals will lessen the tensions that exist
between gray and green infrastructure in Renton. The opportunities and challenges for
advancing an equity-centered approach to expanding tree canopy are innumerable, though
the adoption and implementation of tree canopy goals is an immediate opportunity to advance
such approaches.
An urban tree canopy goal that addresses equity will need to demonstrate its value to enable
community members to do more than they ultimately would have been able to accomplish
without it. Disinvested communities in the region want more equitable policies, living-wage
jobs, higher household incomes, safer neighborhoods, affordable housing, a more usable and
connected urban network, pedestrian infrastructure, more frequent transit service, better
funding for schools, and specific initiatives to engage youth and families, among other things.
Showing the value of an equity-based tree program and canopy goal that helps to advance
these well-known needs will create an immediate and Citywide constituency for making
Renton more sustainable through actions at the neighborhood level. The Citywide and local-
level canopy goals aim to address these concerns and opportunities.
Current State of Renton’s Urban Forest 24 | P a g e
STRUCTURE OF THE PUBLIC TREE POPULATION
For an understanding of the urban forest that is directly managed by the City, analyses of public
tree inventory datasets were completed. Tree composition data is essential since the types of
trees present in a community greatly affect the amount of benefits produced, tree maintenance
activities, budgets, planting goals, canopy connectivity, and the City’s ability to respond to
threats from invasive pests and diseases.
Table 1. Distribution of public trees by Site Design
Results
The public tree population is
comprised of street and park trees. Of
the total 29,289 public trees with Site
Design values, there are 11,309 street
trees, over 6,000 trees in unimproved
right-of-way, more than 8,000 park
trees in maintained areas, 2,134 trees
in natural areas, and 817 trees on City
properties. The inventory database
does not include the 89,528 total natural area trees or trees in unmaintained areas of public
parks.
Discussion/Recommendations
The extent and distribution of public trees across the City impacts the structure of the
maintenance program and the demand for services. To manage the urban forest for health and
public safety, it is recommended street trees be pruned on a 7-year cycle meaning each street
tree is pruned within a 7-year timeframe to address clearance issues, structural defects,
diseased/decayed/damaged/dying limbs, and other routine maintenance. Currently, the City
primarily contracts pruning and removals with approximately 350 trees pruned by contractors
and 400 trees pruned by the Urban Forester, Inspecting Arborist, or Parks & Trails crews.
Approximately 300 trees are removed annually. With 750 trees pruned each year, the City is on
a pruning rotation of approximately 37 years for all 27,456 public trees (street, park, golf course
trees) or 15 years for only the street tree population.
Site Design Count %
Street 11,309 39%
Park 8,008 27%
Unimproved Right-of-Way 6,068 21%
Natural Area 2,134 7%
Parking Lot 826 3%
City Building 817 3%
Not Available 127 0%
TOTAL 29,289 100%
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 25 | P a g e
Table 2. Public tree genera diversity (top 10)
Genus Count %
Acer 8,010 27%
Pseudotsuga 3,133 11%
Populus 2,932 10%
Alnus 2,203 8%
Thuja 2,004 7%
Prunus 1,775 6%
Pyrus 988 3%
Salix 953 3%
Fraxinus 847 3%
Pinus 809 3%
Other species 5,642 19%
TOTAL 29,296 100%
Acer
27%
Pseudotsuga
11%
Populus
10%Alnus
8%
Thuja
7%
Prunus
6%
Pyrus
3%
Salix
3%
Fraxinus
3%
Pinus
3%
Other
19%
Figure 17. Public tree genera diversity
PUBLIC TREE GENERA DIVERSITY
Acer → maples
Pseudotsuga → Douglas-firs
Populus → cottonwoods
Alnus → alders
Thuja → red cedars
Prunus → plums, cherries, peaches, others
Pyrus → pears
Salix → willows
Fraxinus → ash trees
Pinus → pines
Current State of Renton’s Urban Forest 26 | P a g e
The following provides a summary of the top ten species identified during the 2021 tree
inventory data analysis. Note the values differ slightly from the 2021 Urban Forest Inventory and
Resource Analysis Summary Report due to everchanging conditions and routine maintenance.
Table 3. Public tree species diversity (top 10)
Common Name Count %
Bigleaf maple 4,322 15%
Douglas-fir 3,132 11%
Black
cottonwood 2,771 9%
Red alder 2,198 8%
Red maple 1,920 7%
Western red
cedar 1,529 5%
Callery pear 977 3%
Norway maple 870 3%
Pacific willow 693 2%
Purple leaf plum 650 2%
Other species 10,245 35%
TOTAL 29,307 100%
Bigleaf Maple
15%
Douglas-fir
11%
Black
cottonwood
9%
Red
alder
8%
Red
maple
7%
Western red cedar
5%Callery Pear
3%
Norway
maple
3%
Pacific
willow
2%
Purple leaf
plum
2%
Other
35%
Figure 18. Public tree species diversity
PUBLIC TREE SPECIES DIVERSITY
Bigleaf maple Douglas-fir Black cottonwood Red alder Red maple
Western red cedar Callery pear Norway maple Pacific willow Purple leaf plum
Figure 19. Leaf profiles of the most common public trees (not to scale)
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 27 | P a g e
Results
Based on the inventory data there exists a total of 90 unique genera with the top five comprised
of Acer (27%), Pseudotsuga (11%), Populus (10%), Alnus (8%), and Thuja (7%). The top five genera
make up 63% (18,282 trees) of the 29,296 total live trees recorded in the 2021 inventory update.
Regarding species diversity, there exists a total of 281 unique tree species. The top ten species
comprise 65% of the inventory consisting of bigleaf maple (15%), Douglas-fir (11%), black
cottonwood (9%), red alder (8%), red maple (7%), western red cedar (5%), callery pear (3%),
Norway maple (3%), pacific willow (2%), and purple leaf plum (2%).
The composition of a tree population should follow the 10-20-30 Rule for species diversity—a
single species should represent no more than 10% of the community forest, a single genus no
more than 20%, and a single family no more than 30%. Based on this rule, bigleaf maple (Acer
macrophyllum) and Douglas-fir (Pseudotsuga menziesii) exceed the recommended 10%
maximum for a single species in a population, comprising a combined 26% of the inventoried
tree population. Regarding the genus threshold, maples (Acer) exceed the recommended 20%
maximum for a single genus in a population, comprising 27% of the inventoried trees.
Discussion/Recommendations
Bigleaf maple dominates the tree population at 15%. After bigleaf maple, Douglas-fir makes up
the second highest portion at 11%. For a sustainable and resilient urban forest, Douglas-fir,
bigleaf maples, and maples in general, should be limited in new tree installations.
As a result of the large quantity of Acer (maple) in the City’s population, along with its
susceptibility to Asian longhorned beetle (ALB, Anoplophora glabripennis), verticillium wilt,
and granulate ambrosia beetle (Xylosandrus crassiusculus), the planting of Acer should be
limited to minimize the potential for loss in the event that these pests appear in the City’s urban
forest. Regarding the second most prominent specices, Douglas-fir faces Rhabdocline
needlecast, Swiss needlecast, and twig blight which all affect the condition and performance
of the trees if not addressed. Therefore, this species should be limited in new plantings.
Low species diversity (large proportion of the population consisting of trees of the same species)
can lead to severe losses in the event of species-specific epidemics such as the devasting results
of Dutch elm disease (DED, Ophiostoma novo-ulmi) and more recently, emerald ash borer (EAB,
Agrilus planipennis). Asian longhorned beetle is a major threat to Renton’s urban forest, over
25% of the tree population is comprised of trees in the Acer (maple) genus. Tree species diversity
is crucial to the resilience of the community forest from these and future unknown threats.
The Tree Planting Initiative section provides the guidance for strategic planning and planting
of the urban forest to reduce susceptibility and maintain sustainability.
Current State of Renton’s Urban Forest 28 | P a g e
PUBLIC TREE POPULATION SIZE CLASS DISTRIBUTION (RELATIVE AGE)
The distribution of tree ages influences the structure of the urban forest as well as the present
and future costs to the City or property owners. An uneven-age urban forest offers continued
flow of benefits and a more uniform workflow allowing managers to more accurately allocate
annual maintenance funds. The inventoried trees were categorized into the following diameter
size classes: young trees (0-6 inches DBH or diameter at breast height measured at 4.5 feet),
established (7-12 inches DBH), maturing (13-18 and 19-24 inches DBH), and mature trees (25-30
and >30 inches). Since tree species have different lifespans and mature at different diameters,
heights, and crown spreads, actual tree age cannot be determined from diameter size class
alone. However, general classifications of size can be extrapolated into relative age classes.
YOUNG ESTABLISHED MATURING MATURE
19%
30%
24%
11%
7%8%
40%
25%
15%
10%
6%4%
0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
0-6in 7-12in 13-18in 19-24in 25-30in >30in
City Distribution Ideal Distribution (Richards, 1993)
Figure 21. Distribution of public trees by diameter (DBH) class compared to the ideal distribution
PUBLIC TREE SIZE DISTRIBUTION COMPARED TO THE IDEAL DISTRIBUTION
Figure 20. Distribution by Diameter (DBH) class within site design classifications
PUBLIC TREE SIZE DISTRIBUTION FOR VARIOUS SITE DESIGNS
-
200
400
600
800
1,000
1,200
1,400
1,600
1,800
2,000
City
Building
Natural Area Park Parking Lot Street Unimproved
ROW
0-3"4-6"7-12"13-18"19-24"25-30">30"
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 29 | P a g e
Results
The diameter classes were chosen so that the tree population could be analyzed according to
Richards’ ideal distribution (1983).2 Based on the analysis, the distribution trends towards less
ideal; young trees comprise less than half the recommended distribution with 19% instead of
40%. Renton’s distribution of trees in the 7-12-inch and 13-18-inch size classes exceed the ideal
distribution but the trees 19 inches or greater in diameter closely resemble the ideal distribution.
Discussion/Recommendations
Richards proposed an ideal diameter size class distribution for street trees based on
observations of well-adapted trees. Richards’ ideal distribution suggests that the largest fraction
of trees (approximately 40% of the population) should be young (less than 8 inches DBH), while
a smaller fraction (approximately 10%) should be in the large-diameter size class (greater than
24 inches DBH). A tree population with an ideal distribution would have an abundance of newly
planted and young trees, and lower numbers of established, maturing, and mature trees.
Table 4. Summary of Renton’s tree size distribution compared to the ideal distribution
In the public tree population, Renton has too few young
trees and an overabundance of established trees (7-18
inches in diameter) and a slightly overabundant population
of mature trees (>25 inches in diameter) suggesting an
overly maturing tree population. A goal for Renton’s urban
forest should be to have an uneven-aged distribution of
trees at the street, park, and Citywide levels. An aging tree
population poses a potential increase in maintenance and
removal demands and may leave a void in tree canopy and
associated benefits if tree planting levels are not elevated.
The City is below the threshold for young trees and it will
also suffer a loss of ecosystem services that were provided
by the mature trees if tree plantings do not increase.
It is recommended that Renton support a strong planting
and maintenance program to ensure that young, healthy trees are in place to fill in gaps in tree
canopy and replace older declining trees. The City must promote tree pre servation and
proactive tree care to ensure the long-term survival of older trees. Additionally, tree planting
and tree care will allow the distribution to normalize over time.
The distribution of individual tree ages within a tree population influences pr esent and future
costs as well as the flow of benefits. An ideal age/size distribution in the tree population allows
managers to allocate annual maintenance costs uniformly over many years and assures
continuity in overall tree canopy coverage and associated benefits which are often dependent
on the growing space of individual trees (e.g., open grown versus restricted growing areas).
As stated earlier, the City’s public tree maintenance program is influenced by the size classes
and relative age, among other factors. The City should support the tree canopy cover goals
recommended in this Plan to increase the number of new trees in the 0-6-inch range,
strengthen tree regulations to protect the medium to large trees, and proactively remove and
replace the declining large trees that pose potential risks as they approach senescence.
2 Richards, N. A. 1983. “Diversity and Stability in a Street Tree Population.” Urban Ecology 7(2):159–171.
0-6in LOW
7-12in HIGH
13-18in HIGH
19-24in IDEAL
25-30in IDEAL
>30in HIGH
Current State of Renton’s Urban Forest 30 | P a g e
VALUE AND BENEFITS OF THE PUBLIC TREE POPULATION
The urban forest plays an important role in supporting and improving the quality of life in
communities. A tree's shade and beauty contribute to a community’s quality of life and soften
the often hard appearance of urban landscapes and streetscapes. When properly maintained,
trees provide communities abundant environmental, economic, and social benefits that far
exceed the time and money invested in planting, pruning, protection, and removal.
Not only do the trees growing along the public streets constitute a valuable community
resource, they are actual City assets. They provide numerous tangible and intangible benefits
such as pollution control, energy reduction, stormwater management, property value increases,
wildlife habitat, education, and aesthetics.
Benefit Analysis of Renton’s Public Trees
The services and benefits of trees in the urban and suburban setting were once cons idered to
be unquantifiable. However, by using extensive scientific studies and practical research, these
benefits can now be confidently calculated using tree inventory information. Tree benefit values
for the City of Renton’s trees are summarized in this Plan using the findings from Renton’s
Urban Forest Inventory & Resource Analysis Summary Report, which was published in January
of 2021, and calculated using the U.S. Forest Service’s i-Tree’s Streets and i-Tree Eco applications.
The results of Renton’s tree inventory provide insight into the overall health of the City’s public
trees and the management activities needed to maintain and increase the benefits of trees into
the future.
The 2021 inventory report calculated benefits for 116,994 trees representing three main tree
populations in Renton: street and park trees (public rights -of-way and landscaped parks),
natural areas (various forest types such as wetlands, steep hillsides, and riparian), and the
Maplewood Golf Course (owned and maintained by the City of Renton). The following sections
summarize the benefits of these tree populations analyzed in the 2021 report.
To identify the dollar value provided and returned to the community, the City’s tree inventory
data were formatted for use in the i-Tree Canopy and i-Tree Eco benefit-cost assessment tools.
These applications analyze an inventoried tree population’s structure to estimate the costs and
benefits of that tree population. The assessment tools create annual benefit reports that
demonstrate the value the City’s trees provide.
Table 5. Summary of ecosystem services, benefits, and values of Renton's public trees
Tree
Population Method
Total #
of Trees
Annual
Benefits
per Tree ($)
Annual
Benefits per
Capita ($)*
Total
Annual
Benefits
Replacement
Value
Street and
Park Trees i-Tree ECO 25,772 $2.34 $0.66 $60,147 $30,600,000
Natural
Area Trees
i-Tree
Canopy 89,528 $1.73 $1.52 $155,141 $90,000,000
Maplewood
Golf Course Extrapolated 1,694 $2.34 $0.04 $3,964 $2,000,000
TOTAL 116,994 $1.88 $2.22 $219,252 $122,600,000
*Annual Benefits per Capita ($) based on an estimated population of 90,000 people at the time of the study
Current State of Renton’s Urban Forest 31 | P a g e
Stormwater: Presents reductions in annual
stormwater runoff due to rainfall
interception by trees measured in gallons.
Air Quality: Quantifies the air pollutants
(ozone [O3], nitrogen dioxide [NO2], sulfur
dioxide [SO2], particulate matter less than
10 micrometers in diameter [PM10])
deposited on tree surfaces, and reduced
emissions from power plants (NO2, PM10,
volatile organic compounds [VOCs], SO2)
due to reduced electricity use in pounds.
The potential negative effects of trees on air
quality due to biogenic volatile organic
compounds (BVOC) emissions is also
reported.
Energy: Presents the contribution of the
urban forest towards conserving energy in
terms of reduced natural gas use in the
winter (measured in therms [thm]) and
reduced electricity use for air conditioning
in the summer (measured in Megawatt-
hours ([MWh]).
Aesthetic/Other Benefits: Shows the
tangible and intangible benefits of trees
reflected by increases in property values (in
dollars).
Carbon Stored: Tallies all of the carbon
dioxide (CO2) stored in the urban forest over
the life of its trees as a result of
sequestration. Carbon stored is measured in
pounds.
Carbon Sequestered: Presents annual
reductions in atmospheric CO2 due to
sequestration by trees and reduced
emissions from power plants due to
reductions in energy use. This is measured
pounds and has been translated to tons for
this report. The model accounts for CO2
released as trees die and decompose and
CO2 released during the care and
maintenance of trees.
Importance Value (IV): IVs are calculated for
species that comprise more than 1% of the
population. The Streets IV is the mean of
three relative values (percentage of total
trees, percentage of total leaf area, and
percentage of canopy cover) and can range
from 0 to 100, with an IV of 100 suggesting
total reliance on one species. IVs offer
valuable information about a community’s
reliance on certain species to provide
functional benefits. For example, a species
might represent 10% of a population but
have an IV of 25% due to its substantial
benefits, indicating that the loss of those
trees would be more significant than just
their population percentage would suggest.
Replacement Value: Replacement values
are estimates of the full cost of replacing
trees in their current condition, should they
be removed for some reason. Replacement
values are based on the Council of Tree and
Landscape Appraisers (CTLA) Guide for Plant
Appraisal, which uses a trunk formula
methodology.
Current State of Renton’s Urban Forest 32 | P a g e
Figure 22. Illustration of the benefits and services provided by public trees
Street and Park Tree Benefits
A total of 25,772 trees were inventoried as part of the inventory covering Renton’s streets and
parks. The tree inventory data was processed using i-Tree ECO, which estimated that these areas
have 654.7 acres of canopy cover. The annual benefits provided by these trees is over $60,000
and the total replacement value is nearly $3 million.
Table 6. Summary of the annual benefits provided by Renton’s public trees*
Benefits Total ($) Quantity
Annual
$/tree
Annual
$/capita
Avoided Stormwater $ 18,948.62 13,846,782 gal $ 0.74 $ 0.21
Carbon Sequestered $ 24,124.00 141.5 tons $ 0.94 $ 0.27
Air Quality $ 17,074.35 5,549.33 lbs $ 0.66 $ 0.19
Carbon Stored $ 2,287,708 (lifetime) 13,414 tons
Total Annual Benefit $ 60,146.97 $2.34 $0.67
*Distribution of benefits per tree and per capita based on 25,772 trees and a population of ~90,000 people
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 33 | P a g e
Natural Area Tree Benefits
Renton has approximately 854 acres of natural areas, with an estimated 89,528 trees covering
84% of that acreage (721 acres). These trees provide the same ecosystem benefits of street and
park trees; however, they are not typically in conflict with the built environment and therefore
they are maintained less often and left to live longer lives. As such, i-Tree Canopy does not
calculate a monetary value for avoided stormwater because stormwater in natural areas is more
likely to flow into streams and wetlands than city stormwater drains.
Table 7. Summary of the benefits and services of trees in natural areas
Benefits Total ($) Quantity
Avoided Stormwater N/A 461,306.84 gallons
Carbon Stored $ 3,687,700.00 216,221.31 tons
Carbon Sequestered $ 146,840.00 860.97 tons
Air Quality $ 8,301.00 48,356.65 lbs
TOTAL $3,842,841
Maplewood Golf Course Tree Benefits
As a part of Renton’s Urban Forest Inventory & Resource Analysis Summary Report, 1,684 trees
were inventoried and analyzed. The benefits for these trees were extrapolated from the average
annual benefits provided by Renton’s street and park trees. It was estimated the trees
inventoried on Maplewood Golf Course provide $3,964 in annual environmental benefits and
have a replacement value of $2,000,000.
Current State of Renton’s Urban Forest 34 | P a g e
RENTON’S
URBAN
FORESTRY
PROGRAM
Current Urban Forest Management Challenges 35 | P a g e
CURRENT URBAN FOREST MANAGEMENT CHALLENGES
OVERVIEW
The City of Renton has a unique urban form and character. Its size, layout, and development
density influence the landscape and has created a charming and livable city. Renton’s citizens
show pride in their city, and their neighborhoods are well cared for. The City’s climat e is ideal
for a wide range of plants and street trees and many of the City’s streets and landscapes exhibit
a unique and rich planting character. Some of the City’s historic neighborhoods and its newest
developments have a rich urban forest that illustrates Renton’s potential to be an even greater
tree-filled city guided by a strategic plan— a city that can be truly ‘ahead of the curve’.
Urban trees can play a significant role in making cities resilient to weather and climate
extremes, and in protecting human and ecosystem health and safety. To do so, trees must be
consciously selected, planted, and managed as the central component of an urban forest where
individual trees are maintained as part of a greater system with the purpose of improving the
urban environment and enhancing the benefits of that ecosystem.
Yet the ability of Renton’s trees to achieve the
desired maximum return of benefits is limited
due to poor maintenance and management
stemming from insufficient municipal budgets,
underdeveloped urban forest management
systems and programs, limited training of tree
care professionals, and a lack of enforcement of
tree-management best practices to support tree
health. Consequently, long-term tree health is
compromised resulting in limiting the beneficial
functions of trees, leaving trees more susceptible
to pests and disease, and leading to premature
tree death. The impact of this is compounded for
disadvantaged communities in Renton. As
stated by Jad Daley, president and CEO of
American Forests, “The single greatest threat
from climate change to people in cities is
extreme heat.”
In turn, urban trees in Renton face multiple
challenges to surviving and thriving. Trees that
die years prematurely will not create the root
systems and canopies needed to reach their
benefit potential and maximize their return on
investment. Planting and maintaining an urban
forest that exists in concert with other green
infrastructure must include management by trained individuals, the use of tree inventory data,
an understanding of baseline conditions and forecasted environmental changes, collaboration
among departments to mainstream urban forest management, a community with a shared
vision for the urban forest, and a roadmap for management provided in a plan.
Current Urban Forest Management Challenges 36 | P a g e
CHALLENGES IN MAINTAINING AND MANAGING PUBLIC TREES
There are a total of 27,456 public street and park trees and 89,528 natural area trees in Renton
that are the responsibility of the City to maintain and manage. In 2009, the Community Services
Department maintained 1,000 street trees within the downtown core and all park trees with
the goal of pruning trees on a five-year cycle. Maintenance was split between City staff for
routine care and private contractors for larger trees and more technical arboriculture work. The
Public Works Street Division maintained the public right -of-way by responding to tree
clearance issues and downed limbs from any of the 3,200 trees in the right-of-way at the time.
Sustainable Management – Pruning Cycles
Today, the Urban Forestry Program manages and administers general forestry maintenance
contracts for public tree planting, trimming, removals, consultancy, watering, and inspections
and the Public Works Street Division continues to prune trees for clearance and address
downed limbs in the public right-of-way. Parks & Trails crews also manage many tree issues on
an as needed basis within park areas and along trails. This structure provides a more holistic
approach to public tree management by extending maintenance beyond the downtown core
trees but the budgets inhibit efficient proactive management and compromise sustainability.
One measure of sustainable management is the number of years it takes to prune all public
trees, also referred to as the pruning cycle. Currently, the City is on an approximate 37-year
pruning cycle compared to the recommended 7-year cycle. The impact of deferred
maintenance is seen in the condition of the inventoried public tree population with nearly half
rated as fair in condition and only a third in good condition. Compounding the issue, both the
Parks & Trails Division and the Public Works Street Division have limited in resources and have
extensive demands to meet in regards to parks and trails maintenance and sidewalk repairs &
replacements, respectively.
Program Efficiencies
Having public tree maintenance responsibilities shared across departments can utilize limited
resources efficiently but only if the workflows are clear and understood. An example where the
workflow is complicated and inefficient lies within tree clearance issues for both public and
private trees impacted the right-of-way. These tree issues are received through Renton
Responds, staff observations, calls, or through Verra Mobility (the City’s traffic signal company).
If the clearance issue is the result of a tree branch, Public Works Transportation Maintenance
address the issue if it is a minor branch, or the issue is sent to code compliance for private trees
and to Urban Forestry for public trees. For minor public tree clearance issues, Urban Forestry will
sometimes address the problem with a pole saw from the ground, but the number of requests
continue to backlog and Urban Forestry had to build a dedicated worklist and contract for less
urgent tree clearance work of both public and private trees. For private trees, Code Compliance
could require the property owner to remedy the issue but for single private trees the process
and burden is onerous— the resident would need to pay for a right-of-way use permit in addition
to the cost of trimming, so it is often avoided and instead the tree is queued and eventually
addressed but results in significant backlogs.
Risk Tree Management
One of the unique challenges of managing Renton’s urban forest stems in part from the nature
of trees in the Pacific Northwest – trees grow exceptionally tall. Small pockets of remnant stands
of second growth trees can still be seen even today at the edge of new developments. They can
be more prone to branch failures than other tree species during storms. In addition to large tree
size, the prevalence of particular species in the urban forest population presents more
opportunities for possible damages and consequences as a result of the failure of a tree or tree
part. Other native species like bigleaf maples and black cottonwoods can also be problematic
as they are also large trees and are prone to decay. They comprise a large proportion of the
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 37 | P a g e
public tree population, especially in natural areas. There are also large specimen trees like pin
oaks, tulip trees, cedars, and sycamores on city streets which require thoughtful management.
Tree Related Policies and Regulations
Trees can be found mentioned in several City codes, regulations, and plans. Regulations to guide
tree planting and maintenance are limited and do not sufficiently address the concerns of many
City staff and the public. For example, there are limited regulations about planting trees near
street lights. Though section 4-4-070F.2 of Renton Municipal Code provides some guidelines for
planting near objects in the right-of-way, additional detailed language could address concerns.
Removing trees during construction of subdivisions became a problem after 2000 when the
City experienced a period of rapid development. An emergency rule was invoked in late 2006
followed by adoption of the tree retention regulation in 2007 to deal with loss of canopy cover
in new development. Legislation affecting the City of Renton is not only local in nature. Other
state and federal legislation impacts trees in the city directly or indirectly. One of these is the
Evergreen Communities Act which passed the State Legislature in 2008. This act specifically
benefits urban forestry across the state for local jurisdictions.
Regulations exist for planting, pruning, and removing street trees. A new Street Tree Regulation
has been developed to provide guidance on maintenance and planting. Additional regulations
will be incorporated into the Renton Municipal Code to improve tree protection and
preservation. Regulations include plan review for street tree planting, pruning and removal;
spacing guidelines and tree species selection for street trees; permits for land use, clearing and
tree removal; and hazardous tree mitigation. Though significant improvements have been
made, there still exist some inconsistencies or gaps in the policies and regulations for Renton’s
trees.
Tree Retention Requirements
When calculating tree retention density requirements on residential parcels, credit is given for
every six (6) inches of tree diameter at breast height (DBH) for larger trees retained, as opposed
to 1 for 1 replacement or retention. The upside is that for correcting violations by replanting,
every inch of diameter must be replaced. For infrastructure projects however, the replacement
value is 1 for 1. This does not quickly replace the diameter of larger trees lost due to infrastructure
projects. Also, the main elements for tree preservation are retention density and landmark size
(trees greater than 30 inches DBH).3 Industry recommendations and benchmarking research in
other cities show a landmark tree size classification should be reduced to at least 24 inches DBH
(Swiecki, et al. 1991).
Tree Removal Permits
All permitting for tree removals is coordinated through the Community and Economic
Development Department. As is often the case for municipalities with less stringent tree
preservation ordinances, tree value lost after removal for development is not always sufficiently
captured in replacement tree planting. Urban Forestry divisions are not always looped in
consistently during the design, land use and construction permi tting process. In Renton
however, this improved after the tree ordinances were reviewed in 2019 and the Urban Forestry
Division was more explicitly included in both land use discussion and construction permitting .
Many cities require removal permits for any tree over six (6) inches DBH, and removals are not
granted unless the tree is dead, diseased, structurally compromised, exceeded growth space, is
less important than planned infrastructure, or poses an unacceptably high level of risk. Lost tree
value can be recouped in the permitting process and is highly recommended and desired by
3 Public (SEPA exempt) utilities and public ROW expansions are exempt from tree density; however, street trees are required
per RMC 4-4-070, landscaping. Thus far, the proposed tree ordinance does not intend to apply the proposed tree credit system
to public ROW trees.
Current Urban Forest Management Challenges 38 | P a g e
the City, but, would likely require a full-time development review arborist.
Tree Protection during Construction
Currently, Best Management Practices (BMPs) for protecting tre es on construction sites are
inconsistently adhered to by contractors and the monitoring of tree protection zones (TPZ) is
insufficient due to poor understanding of the BMPs on the part of the contractors and the
inability for the City’s inspection team to provide 24/7 oversite on all development projects.
Alternative Solutions to Tree and Sidewalk Conflicts
Many municipalities habitually apply linear streetscape designs which limit retrofits and
alternative solutions to tree and sidewalk conflicts. Renton has made some use of flexible
design, however these types of designs could be considered more often. Flexible design would
allow more sidewalks to meander around trees, parcels could be developed around healthy
existing trees, and additional right-of-way easements/frontages could be obtained rather than
blindly applying the ‘safe streets’ or ADA retrofit designs. The Urban Forestry Program is actively
discussing potential changes to Code and regulations with Community & Economic
Development.
ADDRESSING THE CHALLENGES
These issues and challenges recognized in Renton are exacerbated in disadvantaged areas of
communities with limited resources. The City needs this comprehensive plan to preserve and
expand the urban forest which results in an equitable distribution of tree canopy, associated
benefits, and urban forestry opportunities. The City, its partners, and the community support a
plan for the urban forest that sustains the resource and provides benefits to all who live, work,
and recreate in the City.
To address these challenges, the Urban Forest Management Plan 10-year Update offers Renton
an opportunity to study, evaluate, and plan for improving urban forest management toward the
goal of supporting human and ecosystem health and well-being. The urgency of protecting the
urban forest has risen sharply as drought, pests, disease, climate impacts and budget cuts lead
to rapidly rising tree mortality. To address and reverse tree die-off and the loss of ecosystem
benefits, Renton needs a robust system of professional management of public trees and
improved support of resident engagement in the care and expansion of the urban forest, both
public and private.
When making improvements to the urban forest, efforts should be prioritized to improve
environmental justice, equity, access, and levels of service for underserved and vulnerable areas.
These considerations may include additional tree plantings for more equitable distribution of
urban forest cover and benefits, intensive tree management, diverse outreach approaches, and
unique stewardship programs.
Renton’s Urban Forest Management Plan is a crucial planning effort to build a more sustainable
resource and a healthy community, among other core urban forest management elements. This
strategic plan for Renton’s urban forest aims to help guide how the City might think about
strengthening City Code, policies, ordinances, standards, practices, and procedures; analyzes
staffing structures and authority; identifies opportunities for su stained and diversified funding;
provides guidance for routine and systematic inventories and assessments; identifies tree
maintenance efficiencies and planting/canopy goals and priorities; addresses storm, disaster,
and risk management needs; and strengthens community outreach, education, and
engagement.
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 39 | P a g e
PROGRAMS MANAGING RENTON’S URBAN FOREST
PROGRAM ORGANIZATION
Renton’s urban forest is managed by the Parks Planning and Natural Resources Division in the
Parks and Recreation Department (previously referred to as the Community Services
Department). This division is dedicated to the health and protection of the environmental
resources, public safety, and community education for all to enjoy the 711 acres of natural areas,
27,456 public trees along streets, in parks and the golf course and 89,528 trees in natural areas.
In addition, the Division provides landscaping and maintenance within the right-of-way and on
facility grounds at 50 locations. The Urban Forestry Program within the Division is focused on
programming, inventory data collection and management, tree planting, training, tree
inspections, arboriculture related support for tree code enforcement, volunteer restoration
projects, arboriculture related support for site plan reviews, and events like Arbor Day and Earth
Day. These essential duties and responsibilities are overseen by the Urban Forestry and Natural
Resources Manager and supported by a contracted inspecting arborist, a part-time
administrative person, and a part-time supervisor.
Parks and Recreation
Department
Parks Planning and Natural
Resources Division
Urban Forestry Program
Supervisor (0.25 FTE)
Urban Forestry and Natural
Resources Manager (1.00 FTE)
Contracted Inspecting Arborist
(1.00 FTE)
Administrator (0.25 FTE)
Figure 23. Structure of Renton's Urban Forestry Program
INTERDEPARTMENTAL MANAGEMENT OF TREES
There are a wide range of management activities necessary to maintain an urban forest and
many of these overlap between city departments and divisions. The overlap is often based on
the location of a tree on publicly managed land or on private property. In the City of Renton,
public trees on streets, in parks, and in natural areas are the responsibility of the Urban Forestry
Program. Trees on private property fall under the Department of Community and Economic
Development’s (CED) Planning Division, and trees in the public space are managed or
Programs Managing Renton’s Urban Forest 40 | P a g e
supported by the Parks Planning and Natural Resources Division, Parks & Trails Division, Public
Works Maintenance, and Public Works Transportation Systems. The CED Planning Division
oversees private property development, ordinance enforcement, and zoning, with trees on
private property assigned to this department. Likewise, Parks Planning and Development and
Public Works manage public space infrastructure such as streets and sidewalks, and street trees
are organized within these departments. While organizing tree management in this manner is
a natural fit for the responsibilities of each department or division, it does not necessarily
coincide with the expertise and skills of each department, nor does it orchestrate a holistic
management of the urban forest. As such, it is important to review the current structure of the
Renton urban forest for its benefits and tree management limitations, and to explore if
alternative management structures may improve City efficiency and ultimately, lead toward a
safer and sustainable urban forest.
PARKS PLANNING AND NATURAL RESOURCES URBAN FORESTRY PROGRAM
The Urban Forestry Program is responsible for the direct management of 27,456 street, park,
and golf course trees and 89,528 trees in natural areas. Trees located along streets are referred
as street trees. These trees are found between the sidewalk and cu rb in a planting strip or in
sidewalk cut-outs. Street trees are also found within the street right -of-way where no street
exists (dedicated right-of-way), where no sidewalk and curb exists (unimproved right-of-way),
and in some alleys. Street trees require permission to prune, remove, or otherwise treat however,
property owners can water and mulch street trees without permission and the City encourages
these activities for a healthy tree population. These regulations for planting, pruning, and
removing street trees did not always exist. Previously, many street trees were poorly or
improperly maintained, tree removals were made without notice, and poor tree selection and
placement happened when planting. The Street Tree Regulation was developed to address
these concerns and to provide guidance. Regulations include the following:
❖ Plan review for street tree planting, pruning and removal
❖ Spacing guidelines and tree species selection for street trees
❖ Permits for land use, clearing and tree removal
❖ Hazardous tree mitigation
The Urban Forestry Program manages the application for Arbor Day Tree City USA awards and
Arbor Day/Earth Day celebrations. The City has received the Tree City USA award for 14 years and
is eligible to submit applications for Arbor Day Foundation’s Growth Award, which has been
awarded for 11 consecutive years. The Growth Award recognizes Tree City USA communities that
demonstrate higher levels of tree care and community engagement. The Urban Forestry
Program also oversees the permitting process that receives requests for street tree pruning,
removal, inspection, or other requests. The tree(s) associated with a request is identified in the
City’s asset management software and inspections are conducted by the Urban Forestry
Program’s contracted Inspecting Arborist or other qualified personnel. The maintenance or
removal of street trees as requested through the permitting process are staged and prioritized
by the City or addressed by the adjacent property owner. In addition to service requests, the
Urban Forestry Program also conducts proactive pruning of street and park trees.
Previously, the street trees were managed by the Community Services Department and the
Public Works Street Division. The Community Services Department maintained approximately
1,000 street trees within the downtown core and all park trees on a five-year pruning cycle using
staff and private contractors. Private contractors were mostly utilized for larger trees and more
technical work. The Public Works Street Division was responsible for 3,200 trees within the City
right-of-way with maintenance occurring on a reactive basis meaning staff responded to
clearance issues or downed limbs or trees.
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 41 | P a g e
Program Budget
Today, the public street and park trees are managed by the Urban Forestry Program with an
overall budget of $951,000 (2021). Of the total investment, 26% is attributed to administration
($250,000), 17% to consulting arborist inspection services ($157,000), 14% to contract pruning
($134,000), and 11% to professional services ($100,000— only in recent years for inventory and
management plan updates, otherwise it would be spent on pruning, removal, and planting)
and contract landscape watering ($100,000). The remaining 22% ($210,000) is used for tree
removals ($85,000), storm damage on-call / debris clean up ($70,000), tree planting ($35,000),
purchasing trees and planting supplies ($15,000), and pest management ($5,000).
Table 8. Annual investments in the management of street and park trees
Investments (2021) Percent
Allocated Total ($) $/tree $/capita Funding
Source*
Purchasing Trees &
Related Planting Supplies 2% $15,000 $0.55 $0.15 FIL
Planting Trees 4% $35,000 $1.27 $0.34 OP
Contract Pruning 14% $134,000 $4.88 $1.32 OP
Pest Management 1% $5,000 $0.18 $0.05 OP
Removal 9% $85,000 $3.10 $0.84 OP
Storm Damage On-Call /
Debris Clean Up 7% $70,000 $2.55 $0.69 OP
Professional Services** 11% $100,000 $3.64 $0.99 OP
Contract Landscape
Watering 11% $100,000 $3.64 $0.99 CON
Consulting Arborist
Inspection Services 17% $157,000 $5.72 $1.55 CON
Administration+ 26% $250,000 $9.11 $2.46 W&B
TOTALS 100% $951,000*** $34.64 $9.37
*Funding Source Descriptions:
FIL → Fee-in-Lieu fund – separate fund, use restricted to capitalizable purchases for tree planting (ref. RMC 9-13).
OP → Forestry Operating / Maintenance – total maintenance operating funds budget is $425,000.
CON → Externally Contracted Services – funds with separate dedicated budgets; inspection and irrigation.
W&B → Wages and Benefits – estimated, separate from Forestry maintenance budget fund. Based on Urban
Forestry Manager at 100%, Parks Planning & Natural Resources Director at 25%, and Support Staff at 10%.
**Professional Services:
Years 2020, 2021, and 2023 for tree inventory update, management plan update, and LiDAR canopy cover study
which would otherwise normally be spent on pruning, removals, and planting.
***Note:
Budget does not include the tree-related work of the Parks & Trails crews— funded through a separate budget.
+Administration: See Table 9 for summary of 2022 Administration costs.
Programs Managing Renton’s Urban Forest 42 | P a g e
2022 Program Administration Costs
Based on a November 2021 analysis, the administration costs for the 2022 Urban Forestry
Program are provided in the table below:
Table 9. Summary of the 2022 budget for the Urban Forestry Program’s Administration *
Title 2022 Salary 2022 Benefits 2022 Total
Urban Forestry & Natural
Resources Manager (100%) $130,957 $55,251 $186,208
Parks Planning & Natural
Resources Director (25%) $39,290 $18,262 $57,551
Administrative Secretary 1 (10%) $7,776 $4,775 $12,550
TOTAL $178,022 $78,287 $256,309
*Details and Assumptions:
• The percentages assigned to each of the staff represent the amount of time and budget
attributed to urban forestry.
• The Urban Forestry & Natural Resources Manager and the Administrative Secretary’s
benefits remain the same from 2021 to 2022.
• The Parks Planning & Natural Resources Director benefits were adjusted (increased) to a
full family’s cost as a conservative measure.
• A 4% salary increase across the board for non-represented staff at the beginning of 2022.
• A 4% salary increase for AFSCME to mirror the non-represented increase.
Service Requests for Street, Park, and Natural Area Trees
When a service request for a street, park, or natural area tree is received through Renton
Responds or through other channels, the Urban Forestry Program uses the house and street
address for locating trees and to check if they are in the City’s tree inventory database. This
location information is collected in Renton Responds and is used for public and private tree
inspections. The Urban Forestry Program’s contracted Inspecting Arborist inspects trees and
evaluates the tree in terms of general condition and any obvious problems. Prescriptions for
treatment are entered into a work order database only for public trees using a prioritization
procedure. Actual maintenance can take upwards of a year or longer to occur, depending on
the urgency of the risk posed by the tree. Following an inspection, a response is emailed, or
other communications used, to relay information of any action to be taken by either the City or
by the property owner. Some of the more frequent private tree issues encountered include
dangerous trees on adjacent property, inspection of trees from Community and Economic
Development Department staff requests (code compliance, permit applications and
development regulations), and providing general information to property owners about
adjacent city trees.
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 43 | P a g e
Risk Tree Management
The City has actively managed risk trees for over 12 years with a concerted effort beginning in
2009. At that time, the City recognized the need to develop a long-range plan for the
maintenance of the urban forest. To that end, more management information regarding
Renton’s urban forest would be required and the City’s first public tree inventory was created.
This inventory was updated in 2020. With this data, the City’s Urban Forestry Program drafted
the first specified risk tree management plan for Renton’s public trees . The Risk Tree
Management Plan draft is provided in Appendix E and adopting the plan is a strategy in this
Urban Forest Management Plan. Regularly updated tree inventory data will help create
inspections lists and a more proactive inspection rotation for species with a riskier failure profile
and lower recorded condition ratings.
Mainstreaming Urban Forest Management
To ensure sustainability and interdepartmental coordination, a ‘green team’ could be
established to coordinate efforts across the City. This would enable unified messaging,
consistent workflows, improved efficiencies, strengthened and frequent communication, and
improved knowledge transfer. This team may consist of members of the Collaborative Team for
the Urban Forest Management Plan project among others key staff. This idea as part of the
previous urban forest plan in 2009 but never came to fruition.
Programs Managing Renton’s Urban Forest 44 | P a g e
URBAN FOREST BENCHMARK COMPARISONS
Urban forest benchmarking research provides an understanding of the level of effort and
capacity necessary to satisfy the City’s adopted goals, identifies industry trends and best
practices, enables the creation of realistic goals, and provides the metrics for measuring change.
Benchmarking Data Sources
Several data sources were reviewed and compiled to paint a picture of how Renton measures
up against industry standards and communities of a similar size or geographic location and
how its own operations have changed over time.
Phase 1 of the benchmarking process uses the Arbor Day Foundation’s Tree City USA 2019
dataset and compares statistics provided by the City of Renton to other regional cities that also
participate in the Tree City USA program. Using this dataset helps
better understand how Renton’s urban forestry budget and activities
compare to relevant cities. Relevant cities are determined by 1)
proximity (nationwide), 2) proximity (statewide), 3) population size
(nationwide), 4) population size (statewide), and finally 5) within 200
miles and most similar population size (best match). The Tree City USA
dataset is largely focused on: urban forestry budgets, per capita funding
information, and volunteer hours. The data further describes the
number of trees planted, removed, and pruned by City staff. This data is useful in determining
adequacy of urban forestry program funding as well as understanding workloads of those City
employees involved in urban forestry operations.
Phase 2 of benchmarking involves comparing Renton’s urban forestry operations to findings
from an in-depth study conducted by researchers Richard Hauer and Ward Peterson (2014). In
this study, researchers interviewed urban forestry programs in various
regions across the U.S. and among varying population classes. Specific
study focus areas include: community and staff profiles, funding, tree
management policy and planning, volunteers and partnerships,
contracting tree care activities, community tree populations, tree
operations and management, and assistance programs. Data from this
study was compared to data obtained from the City of Renton for the
purposes of determining program health as compared to accurate
data across a range of scales and locations. View the 2014 study by Hauer et al. at
https://www.uwsp.edu/cnr/Pages/Forestry---MTCUS.aspx.
Phase 3 of benchmarking is comprised of presenting the above information to the City and
making clarifications in order to ensure the highest quality analysis. This phase al so includes
internal quality controls to ensure data comparisons are as accurate as possible. In this phase,
data discrepancies and caveats are identified to ensure relevant and compatible comparisons
are made. Information gathered during this process informed the development of realistic and
attainable goals and strategies in the City’s Urban Forest Management Plan.
Understanding the urban forest policies, management approaches, budgets, and programs of
comparable communities and nationwide averages provides comparative data to benchmark
the City’s performance, present and future. While existing tree data describe the current
conditions, benchmarks offer guidance to bring Renton’s urban forestry policies and practices
into alignment with similar-sized cities in Washington and nationwide, enhancing urban forest
management. A summary of research into policies and actions of these cities follows.
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 45 | P a g e
Data Descriptions, Discrepancies, and Limitations
The benchmarking research is based on data reported by communities to the agencies
summarizing the metrics. For the Tree City USA and 2014 Urban and Community Forestry
Census records, the method for reporting budgets and activities may vary among communities
since each community forestry program is unique. The reporting methodology for budgets,
staffing, and activities may differ resulting in less accurate comparisons. Some communities
may only report staffing numbers based on the primary program while others may include
supporting departments, contractors, and technical service providers. These differences in
reporting would also affect the budget comparisons. In addition, the methods for reporting
activities for each community may vary. Some communities may only report on the in -house
activities conducted by the lead department whereas other communities may report on
activities conducted by supporting departments, utility companies, and other sources. Since
the historical reporting methods for Renton are unknown, the values used in the comparison
study are based on 2019 Tree City USA records and 2021-2022 budgets. Due to the number of
discrepancies and the limitations of this analysis, the benchmarking research is meant to serve
as an initial starting point in developing the Urban Forest Management Plan. The metrics are
not meant to imply overall management effectiveness. Interpretations for each metric were
provided and used to guide goals and strategies within the Urban Forest Management Plan. It
is recommended the City verify and finalize benchmarking values in order to measure Plan
implementation progress and inform reporting.
Table 10. Arbor Day Foundation Tree City USA communities examined during the benchmarking research
City State Population Proximity (miles)
Renton Washington 102,153 0
Yakima Washington 94,440 100
Everett Washington 111,215 35
Bellingham Washington 90,110 89
Kirkland Washington 89,557 13
Auburn Washington 81,720 12
Kent Washington 129,600 5
Bellevue Washington 145,300 9
Redmond Washington 65,860 14
Shoreline Washington 55,730 20
Olympia Washington 51,600 46
Burien Washington 50,997 6
Lacey Washington 50,170 42
Tacoma Washington 216,279 19
Bothell Washington 46,657 19
Edmonds Washington 42,170 24
Bremerton Washington 41,235 22
Issaquah Washington 39,378 9
Lynnwood Washington 38,511 23
Longview Washington 38,100 98
Wenatchee Washington 34,329 87
Snoqualmie Washington 13,752 19
TOTAL 1,628,863 713
Average 74,039 32
Programs Managing Renton’s Urban Forest 46 | P a g e
Table 11. Summary of phase 1 benchmarking research results (Tree City USA dataset)
2019 TREE CITY USA - RENTON 2019 TREE CITY USA - REGIONAL
$925k (Urban) Forestry budget $800k Average forestry budget
$9.06 Per capita forestry budget $10.42 Average per capita budget
$647k Tree planting, initial care,
maintenance, and removal
budget
$630k Average tree planting, initial care,
maintenance, and removal budget
$278k Program management budget $121k Average program management
budget
357 Trees pruned 1,025 Average trees pruned
298 Trees removed 130 Average trees removed
129 Trees planted 1,695 Average trees planted
Table 12. Summary of phase 2 benchmarking research results (2014 Census, Hauer et al.)
2014 CENSUS - RENTON 2014 CENSUS – POPULATION GROUP (100-250K)
$925k (Urban) Forestry program
budget (2021) $1.4M Average forestry budget
0.20% Of total budget for forestry 0.52% Of total budget for forestry
117k Estimated public trees 74k Average count of public trees
$7.91 Budget per tree $44.85 Average budget per tree
1.23 Public trees per capita 0.51 Average public trees per capita
47k Public trees per staff 14k Average public trees per staff
711 Acres of parks and open
space 1,284 Average acres of parks and open space
$126M Value of public trees $98M Average value of public trees
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 47 | P a g e
URBAN FOREST AUDIT
To develop this Plan, nearly 40 documents, plans, and resources were gathered and reviewed
by applying the U.S. Forest Service’s Urban Forest Sustainability and Management Audit’s
Discovery Matrix. This matrix includes a total of 11 urban forest categories, each containing a
multitude of supporting elements. All resources were reviewed to identify references regarding
each of the categories and supporting elements. There are a total 275 instances where the 40
resources reference the 11 categories and supporting elements. The number of resources
referencing elements of urban forest sustainability and management demonstrate Renton’s
readiness for changes driven by this Plan. Recommendations in this Plan align with
components of these supporting resources. For a complete list of categories, elements,
rankings, and supporting resources, see Appendix D.
Based on the analysis of findings from the project planning and research, Renton scored a 65%
in terms of urban forest sustainability and management as defined by the U.S. Forest Service,
partners, and planning consultants. The City of Renton scored relatively high when compared
to other urban forestry audits completed by the consultants for other communities of similar
size. Overall, the City scored highest in the Decision and Management Authority, Community,
Professional Capacity and Training, and Inventory categories — all of which are above 75%. The
Urban Forest Management Plan provides the guidance to maintain these strengths and to
address shortcomings as opportunities.
Based on the audit of 129 subcategories (11 primary categories), Renton is achieving “Adopted
Common Practice” for 53 (42%) of these. 59 subcategories (23%) are “In Development”. Applying
the multipliers of 2 for Adopted Practice and 1 for In Development results in a total score of 165
out of 254 possible points, or 65% (detailed in the following table).
Table 13. Outcomes of the urban forest auditing process for Renton, WA
# Description SOC* (%
Achieved)
Base** (%
Achieved)
Overall
Rating
Overall (%
Achieved)
1 Management Policy, Ordinances 75% 50% 18 64%
2 Professional Capacity and Training 100% NA 13 81%
3 Funding and Accounting 75% NA 7 58%
4 Decision, Management Authority 100% 50% 7 88%
5 Inventories NA 63% 20 77%
6 Urban Forest Management Plans NA 25% 11 46%
7 Risk Management 100% 50% 15 83%
8 Disaster Planning NA 67% 6 43%
9 Standards and BMPs*** 75% 56% 33 55%
10 Community 100% NA 24 86%
11 Green Asset Evaluation NA NA 11 55%
TOTAL 89% 51% 165 65%
*Standard of Care (SOC) elements represent the minimum group of urban forestry management “best practices” that
a municipality should consider for implementation. SOC refers to the degree of prudence and caution required of an
individual who is under a duty of care (i.e., legal obligation of the controlling authority, owner, or manag er) to
minimize risk. Neither state, regional, nor national minimum management components have been established for
SOC but these are interim recommendations for consideration. (NA = not applicable)
**Base Practices (BP) elements represent additional urban forest management activities or components that may
effectively expand a program beyond the SOC group (see footnote above). These elements are typically precursors
to other “non-core” elements in the category. (NA = not applicable)
***Best Management Practices (BMPs)
Programs Managing Renton’s Urban Forest 48 | P a g e
Discussion
The main purpose of the urban forest audit is to apply the research and findings gathered
throughout the planning effort to inform the Plan’s goals, objectives, and strategies. This audit
or “gap analysis” enables the Urban Forestry Program to control different aspects of its program
with data. This gap analysis identified the shortcomings that the Urban Forestry Program should
overcome and by quantifying them, the program can make improvements. It also enables
effective monitoring of Plan strategies in that the audit categories and elements can be
revisited at key intervals in the Plan implementation process to measure progress and adapt
strategies accordingly.
The information provided in the table above describe the current conditions of Renton’s urban
forest, the programs that manage it, and the community framework. As recommended in the
Plan’s monitoring methods, the City should use this framework to evaluate implementation
progress, report successes, and inform changes to Plan actions. Many of the urban forest audit
elements were given a rating of “In Development” as they previously did not exist but are
addressed in this Urban Forest Management Plan. This means that the City is already well
underway in advancing its program and its Urban Forest Audit score.
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 49 | P a g e
PROGRAM NEEDS
PUBLIC TREE MAINTENANCE
Urban forest management priorities should in part be determined by the current maintenance
practices and how well they support program goals and the Plan’s goals. Some maintenance
practices are specific to local climate conditions and number of trees to manage. Others, such
as maintaining an optimal pruning cycle are relatively consistent for all tree management
programs. As such, the City’s pruning cycle can be used to identify funding and staffing needs.
Program Needs 50 | P a g e
Current Public Tree Condition and Maintenance Needs
Tree characteristics and outside forces affect
the management needs for urban trees. An
analysis of the condition and maintenance
requirements enables managers to plan the
urban forest, prioritize maintenance, and
target outreach to property owners and the
community as a whole. Tree condition
indicates how well trees are managed and
how well they perform given site-specific
conditions. Tree maintenance needs are
inventoried for public safety reasons and for
the health and longevity of the trees.
Understanding the maintenance needs assists
tree managers in establishing daily work plans.
The condition of individual trees was
catalogued in the City’s inventory database in
numerical values. Dead trees were given a
rating of “0”, poor condition trees a rating of 10-
40, fair condition given 50-60, good condition
with a rating of 70-90, and trees in excellent
condition were given a rating of 100. Several
factors are considered when assigning a
condition value to a tree, including root characteristics, branch structure, trunk, canopy, foliage
condition, and the presence of pests.
Table 14. Public tree maintenance needs by Site Design based on an analysis of August 2021 inventory data
Parking Lot (242 Trees) Street (3,578 Trees) Unimproved ROW (1,712 Trees)
Structural Prune 25% Clearance Prune 22% Crown Cleaning 39%
Clearance Prune 23% Structural Prune 19% Tree Removal 21%
Thinning Prune 17% Thinning Prune 18% Other 12%
Other Maintenance 35% Other Maintenance 40% Other Maintenance 29%
City Building (113 Trees) Park (2,777 Trees) Natural Area (765 Trees)
Crown Cleaning 32% Crown Cleaning 28% Add Mulch 36%
Clearance Prune 29% Thinning Prune 18% Crown Cleaning 21%
Tree Removal 12% Add Mulch 16% Structural Prune 13%
Other Maintenance 27% Other Maintenance 38% Other Maintenance 31%
Nearly half of the public tree population with a condition rating is in the “Fair” condition class
with a numerical value of 50 through 60. With 48% of trees in fair condition, it perhaps is an
indicator of less than optimal tree maintenance, poor tree species for a given site, insufficient
monitoring or plant health care, natural and human-caused defects, a maturing public tree
population, or a combination of factors.
Across all Site Designs— the type of site in which trees are planted and growing — 22% of trees
require crown cleaning, a pruning practice that addresses dead, dying, decayed, diseased, and
damaged limbs. This type of maintenance can be more effectively managed with overall
reduced costs if the public trees were pruned on a shorter cycle.
(0), Dead, 3%
(10-40),
Poor,
15%
(50-60),
Fair, 48%
(70-90),
Good,
33%
(100), Excellent,
0.3%
PUBLIC TREE CONDITION
PUBLIC TREE MAINTENANCE NEEDS BY SITE DESIGN
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 51 | P a g e
Identifying Optimal Pruning Cycles
A study (Miller et al. 20154) was conducted for Milwaukee, Wisconsin to determine the optimum
pruning cycle by comparing the marginal cost of pruning to its marginal return. For example, a
portion of Milwaukee was inventoried to record tree condition and calculate tree value. Since
condition class influences tree value, the date of last pruning and average condition class for
each work unit inventoried was subjected to regression analysis. This analysis determines the
relationship between pruning and condition class (see Figure 24 below). Marginal costs were
calculated based on the loss of tree value, using condition classes, for each one -year extension
of the pruning cycle. Marginal returns are the savings in pruning costs for each one -year
extension of the pruning cycle. For Milwaukee, the relationship between marginal cost and
return indicates that the optimum pruning cycle for the city is five years, assuming the
management goal is to provide the highest-value tree population for dollars expended.
The point at which marginal costs and marginal returns intersect i.e., the optimal pruning cycle.
4 Miller, R. W., Hauer, R. J., & Werner, L. P. (2015). Urban Forestry: Planning and Managing Urban Greenspaces, Third Edition.
64
66
68
70
72
74
76
78
80
0 2 4 6 8 10 12 14Condition Class (%)Number of years since last pruning
0
20,000
40,000
60,000
80,000
100,000
120,000
140,000
160,000
180,000
200,000
0 2 4 6 8 10 12 14Dollars
Pruning cycle length (Years)
Ŷ = 76.7 + 0.196X - 0.074X2*
Marginal cost
Marginal return
a b
Figure 24. a) Relationship between pruning cycle length (number of years since last pruning) and condition class
rating. Asterisk (*) indicates regression is significant at the 0.05 level. b) Marg inal cost (loss of tree value) and
marginal return (savings in pruning costs) for pruning cycle lengths. For this study, the optimal pruning cycle is
where marginal costs and marginal returns intersect— at 5 years. Figure recreated from Miller and Sylvester (1981).
- The Costs of Maintaining and Not Maintaining the Urban Forest: A Review of the Urban Forestry and Arboriculture
Literature (Jess Vogt, Richard J. Hauer, and Burnell C. Fischer, 2015)
OPTIMAL PRUNING CYCLES AND COSTS OF DEFERRED MAINTENANCE
Program Needs 52 | P a g e
An Optimal Pruning Cycle for Renton’s Public Trees
As illustrated in the 2015 study for Milwaukee (Figure 24), a 5- to 7-year pruning cycle is the
optimal intersection of efficiency and safety. If each public tree were to be maintained within a
5- to 7-year window, research shows the trees would be in a safer condition while limiting city
expenses. Based on the analysis (Figure 24), a pruning cycle on a shorter timeframe has a higher
cost to a city but does not correlate to a proportional increase in safety. Conversely, a longer
timeframe lowers costs to a city, but also decreases tree safety.
For Renton specifically, the pruning of public trees is on
an estimated 37-year cycle based on an estimated 750
trees pruned per year and a total of 27,456 public street,
park, and golf course trees (excludes 89,528 trees in
natural areas). Numerous studies have shown the
detrimental effects a delayed pruning cycle can have
on a community’s tree population as well as the
increased risks to public safety. Not pruning street trees
or pruning on such a long rotation is referred to as
deferred maintenance. The costs for deferred
maintenance have been closely examined by
researchers. Prolonged deferred maintenance has a
triple negative effect on costs— it reduces the health
and sustainability of the urban forest, it costs the
residents and adjacent property owners as the associated benefits of trees are diminished as
tree health declines, and costs the City in terms of increased callouts and liability management.
Maintenance can be linked to tree success both at the beginning and end of its lifespan. Early
in a tree’s life, during the establishment and immature (i.e., juvenile) phases, maintenance must
be adequate to ensure early survival and establishment in the urban landscape. Presumably,
any post-planting maintenance performed on a tree that improves its chances of survival to
maturity or lengthens the time that tree spends in its mature phase (where benefits are
produced in the greatest amount) increases the monetary value of that tree. The cost of not
maintaining trees early in life may translate to greater maintenance costs down the road; this is
deferring maintenance (and its costs) to the future in order to save on maintenance costs today.
Later in a tree’s life, maintenance may aim to extend the tree’s lifespan or preve nt tree failure.
In this way, late-stage maintenance can defer removal costs. If maintenance does prolong a
tree’s useful life (i.e., delays the onset of senescence and a tree’s removal), it increases the
amount of benefits it produces over its lifespan. Alternatively, removing the low-hanging limbs
on an aging tree can prevent these limbs from failing and damaging people or property, and
thereby avoid subsequent repair- or liability-related costs. Tree pruning to remove high-risk
limbs and removal of the entire tree can be considered a type of maintenance that potentially
saves money due to avoided litigation costs. With a complete inventory of the public tree
population, the City should determine the costs and optimal schedule for pruning all public
trees, specifically street trees, on a rotation.
The following analysis is based on determining what funding may be needed to maintain the
entire public tree population on a 7-year pruning cycle, to create a baseline for the City to
measure its progression towards a sustainable urban forest.
Based on a market comparison of the costs of program pruning, guidance for implementing
programmed pruning is provided for street, park, and golf course trees (27,456 trees as of 2021).
TREE HEALTH
SAFETY
COSTS ↑
PRUNING ROTATION ↑
Figure 25. As the years between street tree pruning increases, tree health and safety decrease and costs increase
TIME → → → Impacts
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 53 | P a g e
Table 15. Current and recommended maintenance regimen for Renton’s public tree population (street, park, golf course trees)
Public Street, Park, and Golf Course Trees (2021)
Total Tree Count 27,456 trees (2021)
Annual Budget Tree Count
Current Cycle
(~37 Years)
$134,000 750
per year trees per year
20-Year Cycle $247,104 1,373
$113,104 more cost 623 more trees
10-Year Cycle $494,208 2,746
$360,208 more cost 1,196 more trees
7-Year Cycle $706,011 3,922
per year trees per year
2 FTE In-House
Arborist Crew
(7.5-Year Cycle)
4,176 hours (2,088 each)
per year
3,654
trees per year
Cycle Gap between
37-Year & 7-Year Cycle
$572,011 3,172
more per year more trees
Table 16. Assumptions for estimating the additional costs to effectively maintain the public tree population
Renton Estimate Industry Average Lowest Cost
Estimate
Highest Cost
Estimate
$179/tree $180/tree $70.35/tree $200/tree
3,172 more trees 3,172 more trees 3,172 more trees 3,172 more trees
$566,782 $571,011 $233,170 $634,457
The tables above provide a summary of the costs to support programmed pruning of the public
tree population. It should be noted that there are assumptions to the estimated costs for public
tree maintenance. Table 15 above uses the estimated maintenance cost of $180 per tree based
on market research and the City’s annual pruning budget ($134,000) and number of trees
pruned (750). Also, the market research on costs for street tree maintenance found that the
estimates are based on existing grid pruning programs that have been implemented for a
number of years. The City of Renton largely has not been maintaining street trees on a
recommended rotation. Therefore, the per tree cost for grid pruning in Renton may be greater
in the first rotation due to deferred maintenance causing increased maintenance needs and
associated time. For this study, the cost estimates detailed above are used and summarized in
Table 16 for a 7-year rotational programmed pruning cycle compared to the current cycle and
budget. The table includes intermediate cycles for consideration and include 20- and 10-year
cycle estimates and all scenarios assume every public tree needs to be pruned at some point.
A recommended programmed pruning cycle is typically five to seven years depending on the
city’s size, number of trees, types of trees, history of programmed pruning, available funding,
staffing resources, and other factors. For this study, a rotation of seven years is recommended.
RECOMMENDED PUBLIC TREE PRUNING ROTATION
Program Needs 54 | P a g e
Based on the local costs and industry estimates, the costs to pru ne one-seventh of the public
street, park, and golf course tree population (27,456 trees) would increase by $572,011. This
requires the pruning of 3,922 trees annually— 3,172 more trees than the current average. It should
be noted that the costs associated with programmed pruning do not include the costs for tree
removals among other management activities.
Alternatively, if the City were to secure an in-house arborist crew, it is estimated a two-person
(FTE) crew would be able to prune approximately 3,654 trees annually (based on working hours
and average pruning time per tree). For two full-time arborists the costs for salary and fringe
benefits equate to approximately $168,000 annually (not including costs for fleet, operation and
maintenance, or gear). This Plan recognizes the need for increased staffing in order to reach
optimal pruning rotations. The Urban Forestry Program Staffing to Support Sustainable
Management section details the necessary staff and added costs.
To summarize the analysis and calculations, 27,456 trees are along streets, in maintained areas
of parks, or on the Maplewood Golf Course. A 7-year pruning cycle requires 3,922 trees to be
pruned annually. Using the industry average of $180 per tree, the City would need a total annual
budget of $706,011 to maintain this pruning rotation if it were to contract tree pruning, but with
a two-person (FTE) in-house arborist crew, a 7.5-year pruning cycle can be achieved. The cost
estimates for pruning do not account for the maintenance and management of the 89,528 trees
in natural areas that occurs primarily along the wildland-urban interface and trails in the form
of storm damage cleanup and removals.
Priority Maintenance Corridors
A complete overhaul of the public tree maintenance budget and the necessary staff to support
a 7-year pruning rotation should be implemented using a phased approach. It is recommended
the City identify priority roadways and neighborhoods for public tree maintenance based on
density of trees in the rights-of-way, condition and maintenance history of trees, frequency of
disadvantaged communities (e.g., lower than median income, housing value, and other factors),
planned roadway construction, density of tree species requiring frequent maintenance, among
other factors.
The following map provides an example of the potential priority street corridors for the City to
consider to incrementally implement the 7-year pruning rotation. These corridors can also be
the starting point for establishing the framework of the in-house arborist crew. The priority
streets were identified using the public tree inventory dataset, the Tree Equity Scores of Census
Block Groups, and the tree canopy cover within each Community Planning Area.
All Community Planning Areas except for Cedar River and Kennydale have Census Block Groups
with a Tree Equity Score that is less than the recommended 80 out of 100. A total of 19 priority
street corridors were identified. Based on this prioritization, approximately 2,626 trees would be
maintained in the first cycle of proactive maintenance with 1,027 trees in City Center, 497 trees
in Cedar River, 313 trees in Kennydale, 308 trees in Highlands, 197 trees in East Plateau, 194 trees
in Valley, 40 trees in Benson, 35 trees in West Hill, and 15 trees in Talbot (Table 17). Given the
large number of trees in City Center’s priority streets, the Urban Forestry Program may decide
to address only the trees in City Center rather than address all trees across Community Planning
Areas until adequate funding is secured. Tree maintenance should be addressed in these areas
first— as funding permits— until adequate funding is secured and the in-house arborist crew is
established.
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 55 | P a g e
Figure 26. Recommended priority tree maintenance by street corridor and planning area
│ Priority Tree Maintenance Street
0 – 63 Tree Equity Score
64 – 79 Tree Equity Score
Community Planning Areas
● Public trees
Tree points on map are a
sample. Map does not
depict every public tree in
the inventory database
RECOMMENDED PRIORITY PUBLIC TREE MAINTENANCE CORRIDORS
Program Needs 56 | P a g e
Table 17. Recommended streets for priority tree maintenance by Community Planning Area
Community Planning Area Priority Street Corridor Tree Count
Valley
SW 34th St
Oakesdale Ave SW
Lind Ave SW
108 trees
26 trees
60 trees
Talbot Shattuck Ave S 15 trees
Benson SE 164th St 40 trees
Cedar River (No low TES areas)
Maple Valley Hwy
497 trees
East Plateau
Hoquiam Ave NE
156th Ave SE
Duvall Ave NE
86 trees
19 trees
92 trees
Highlands NE Sunset Blvd
NE 4th St
154 trees
154 trees
Kennydale (No low TES areas)
Aberdeen Ave NE
313 trees
West Hill Stevens Ave NW 35 trees
City Center
W Perimeter Rd
Logan Ave N
S Grady Way
Rainier Ave N
Rainier Ave S
2 2nd St
380 trees
281 trees
113 trees
33 trees
125 trees
95 trees
Tree Count Total 2,626 trees
Public Tree Maintenance Recommendations
The Urban Forestry Program should continue to maintain its inventory of public trees to
prioritize tree maintenance and removals and to inform future tree plantings. Nearly half of the
public tree population’s overall health is in fair condition and only a third is in good condition.
Shortening the pruning cycle for all public trees would likely improve the condition of the trees,
reduce clearance issues, and improve public safety. A 7-year pruning cycle is the optimal
rotation. A shorter timeframe has a higher cost to a city but does not correlate to a proportional
increase in safety. Conversely, a longer timeframe lowers costs to a city, but also decreases tree
health, public safety, and depletes urban forest ecosystem benefits. A 7-year pruning cycle
would require the pruning of 3,922 trees per year— an increase of 3,172 trees compared to
Renton’s current average number of trees pruned annually. The total annual budget required
for a 7-year pruning cycle is estimated at $706,011 if contracted and does not include the
maintenance and management of trees in natural areas. An in-house arborist crew of two full-
time employees would cost the City $168,000 annually for salary and fringe benefits (not
including fleet, gear, or operations and maintenance costs) and the staff would be able to prune
the 27,456 street, park, and golf course trees on a 7.5-year cycle. It is recommended the City
make incrementally progress towards a 7-year pruning cycle by prioritizing street corridors in
each of the City’s Community Planning Areas and prune as many trees as the budget allows.
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 57 | P a g e
URBAN FORESTRY PROGRAM STAFFING TO SUPPORT SUSTAINABLE MANAGEMENT
When it comes to program staffing, many cities struggle with the issue of being understaffed.
The programs may be fulfilling their duties within the limited staffing and resources but they
are not performing services that fully capture sustainable urban forest management.
Determining and maintaining optimal staffing levels is critical to a program’s efficiency.
Optimal staffing depends on several factors including number of public trees, authority and
responsibility defined in municipal code, internal and external expectations, customer service
(i.e., the public), operations, and existing programs. The concept of being understaffed also plays
a critical role in employees’ behaviors, attitudes, and directly affects individual productivity. If a
program is understaffed, it typically encounters excess overtime, morale issues, absenteeism,
employee burnout, and have a difficulty with relief coverage and training requirements.
One of the most effective techniques for a city to utilize in determining the optimal staffing
level is to complete an area workload assessment by looking at the number of public trees
managed divided by the total number of staff and using the ratio as a comparison to industry
standards and averages for communities of similar size. The following section provides this
analysis and a recommendation for optimal staffing.
Program Needs 58 | P a g e
Urban Forestry Program Staffing Levels Compared to Industry Recommendations
The number of staff available to perform annual tree maintenance, inspections, and ordinance
/ policy enforcement is a critical element of a sustainable forest. To measure whether staffing is
at a level where sustainable management can occur, the ratio of staff to the number of public
trees is often used. Based on research and industry standards, the optimal ratio for public tree
maintenance is 1 staff for every 2,000 trees. A less aggressive ratio of 1 staff for every 10,000 trees
is also found in the research. But, according to the 2014 Urban and Community Forestry Census
of Tree Activities (Hauer et al. 2014), communities with a population between 100,000 to
249,000 people have an average of 11.8 full-time employees for urban forest management (tree
maintenance and all other services). Communities with a population of 50,000 to 99,999
people have an average of 6.3 full-time employees.
For Renton, assuming all tree maintenance would be done in-house rather than contracted, the
Urban Forestry Program’s arborist crew should contain at least two staff (1 staff for every 10,000
trees managed of 27,456 street and park trees). Currently, the Urban Forestry Program has a
total of 2.50 full-time employees consisting of the full-time Urban Forestry and Natural
Resources Manager (1.00), a full-time Contracted Inspecting Arborist (1.00), a part-time
Supervisor (0.25), and a part-time Administrator (0.25). It is assumed the City would still need to
contract very large tree removals.
Alternatively, the City may continue to contract tree maintenance and removals but
supplement the program with one arborist crew on a less rigorous tree pruning cycle. With the
contracted tree maintenance budget and one arborist crew, the public tree population (street
and park trees) could be pruned on a 7-year rotation. This would require a total of two arborists
though it is recommended a crew supervisor and a seasonal staff member also be considered
in the future. The estimated costs for salaries, fleet/equipment, operation and maintenance, and
gear are provided in the following table.
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 59 | P a g e
Table 18. Estimated staff and associated costs to maintain public trees on a 7-year rotation
Recommended Staff Hours per
Staff
Cost per Hr
per FTE
# of New
Staff Total Cost Estimated Cost
per Staff
B) Arborist 2,088 $40.23 2 $168,000 $84,000
Subtotal -- -- 2 $168,000 $84,000
Equipment Hours Cost/Unit # of Units Total Cost Annual Cost
F350 or equivalent pickup
with dump bed, flasher kit,
extended cab, HD tow kit
1 $60,000 1 $60,000 --
F350 Pickup hours (O&M) 1,000 $16.94 1,000 -- $16,940
Vermeer 1800 brush chipper
with winch 1 $55,000 1 $55,000 --
Chipper hours (O&M) 1,000 $16.94 1,000 -- $16,940
Terex High Ranger bucket truck
with 60+ foot boom length 1 $250,000 1 $250,000 --
Bucket truck hours (O&M) 1,000 $16.94 1,000 -- $16,940
Mid-size Vermeer stump
grinder
SC 382 or equivalent
1 $30,000 1 $30,000
Stump grinder hours (O&M) 1,000 $16.94 1,000 -- $16,940
Heavy duty equipment trailer
Capable of hauling trees or
stump grinder
1 $10,000 1 $10,000
Equipment trailer hours (O&M) 1,000 $16.94 1,000 -- $16,940
Watering rig (500+ gal)
Palettized or tow-behind, with
pump and hose reels
1 $2,000 1 $2,000
Watering rig hours (O&M) 1,000 $16.94 1,000 -- $16,940
Subtotal -- -- -- $410,000 $101,640
Gear Hours Cost/Unit # of Units Total Cost Annual Cost
PPE -- $200 2 $400 $150
Uniforms -- $250 2 $500 $188
Chainsaw -- $800 2 $1,600 $400
Rake -- $25 2 $50 $13
Shovel -- $25 2 $50 $13
Brush Bucket -- $40 2 $80 $20
Cart -- $50 2 $100 $25
Other (e.g. blower) -- $500 2 $1,000 $250
Subtotal -- -- 16 $3,780 $1,058
TOTAL COST $581,780
ANNUAL COST $270,698
Table 19. Summary of costs
Line Item Cost
Annual Staff Cost $168,000
Vehicle and Equipment Purchase $410,780
Annual Operating Costs (supplies, clothing, equipment, rental, etc.) $102,698
Annual Training, Certifications, and Membership Costs $2,000
Program Needs 60 | P a g e
Urban Forestry Program Staffing Recommendations
Based on the needs of Renton’s public tree population, industry standards, and benchmarking
research of analogous communities, it is recommended the City secure an in-house arborist
crew of two arborists and consider supporting the crew with a crew supervisor and seasonal
technician in the future. This recommendation is in alignment with the Task Force’s
recommendation in the 2009 Urban and Community Forestry Development Plan. This would
enable the City to prune the public street and park tree population on a 7-year rotation (3,900
trees per year). With an in-house crew, the budget for contracted tree maintenance and
removals should be focused on annual large tree removals (300 per year on average) and other
contracted services outside of routine tree maintenance.
The estimated initial cost for an in-house arborist crew including fleet, equipment, and gear is
$581,780 with an annual cost of $270,698 (plus an additional $2,000 for annual trainings,
certifications, and membership costs). The annual cost accounts for salary and fringe benefits,
equipment operation and maintenance (O&M) costs, and gear replacement.
The 2009 Task Force agreed on the importance of a dedicated full-time city arborist crew. The
greatest advantages of an in-house crew are in relation to emergency storm damage response
and accomplishing tree work for other emergency situations when contract crews are
unavailable. The arborist crew would prune all street and park trees on a 7 -year rotation and
would also be responsible for the management of all trees on public grounds— street, park,
properties, and natural areas. Other City crews could supplement the arborist crews for special
projects such as pruning trees along sweeper routes in the winter using Public Works staff . The
arborist crew would provide support for other nontree related activities whenever their
equipment might be needed such as assisting Public Works with installing banners or backing-
up other City departments such as Parks & Trails crews when needed.
The Funding Mechanisms section of the Plan provides considerations for funding the in -house
arborist crew. It is recommended the City explore feasible near-term feasible such as using
approximately 75% of the operating budget to fund the two new FTEs and convert ing the
inspecting arborist contract ($157,000) to a further FTE. The City’s ARPA (American Rescue Plan
Act, 2021) funds could potentially support the fleet for the arborist crew.
As shown in the table below, to achieve a 7-year pruning cycle for public trees, the City can
deploy an in-house arborist crew of two full-time employees and reduce costs compared to
contracting all programmed pruning.
Table 20. Comparison of in-house and contracted pruning for a 7-year public tree pruning cycle
In-House Arborist Crew Contracted Difference
Annual Public Tree Pruning
(~3,900 trees/year) $272,698 $705,960 ($433,262)
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 61 | P a g e
Program Budget Final Recommendations
In the Urban Forest Management Plan, guidance for proactively pruning public trees on a 7-year
cycle, establishing an in-house arborist crew, finalizing tree canopy goals, and achieving
planting targets is provided. To accomplish these recommendations that improve overall urban
forest sustainability and tree equity across neighborhoods, the City should evaluate its current
and necessary budgets for the Urban Forestry Program. The following table outlines the
potential costs and the budget necessary to support full implementation of the Plan:
Table 21. Summary of the current and future Urban Forestry Program services and budgets
Line Item
Current Annual
Budget
Future Annual
Budget
Future
Budget Notes
Purchasing Trees &
Related Planting
Supplies
$15,000 $85,500 570 trees per year at $150/tree
Planting Trees $35,000 -- Led in-house
Contract Pruning $134,000 $134,000 Contractor support
Pest Management $5,000 $5,000 Continued management
Removal $85,000 $85,000 Contractor-led
Storm Damage On-Call
/ Debris Clean Up $70,000 $70,000 In-house support
Professional Services $100,000 $100,000
May reduce until new services
needed (e.g., updated inventory
and management plan)
Contract Landscape
Watering $100,000 $100,000 Continued management
Consulting Arborist
Inspection Services $157,000 $157,000 Continued management
Administration $250,000 $256,309 Adjusted for 2022 (see Table 9)
In-House Arborist Crew
Annual Cost -- $272,698
~3,900 trees pruned/year,
includes salary, fringe, and O&M
costs
TOTALS $951,000 $1,265,507 $314,507 increase from 2021
The table above summarizes the 2021 Urban Forestry Program budget and services compared
to the recommended budget for planting, in-house maintenance, and all other services listed.
To achieve the long-term tree canopy goal of 33%, a total of 570 City-led plantings are needed
which can be completed in-house with the new arborist crew. Given the in-house arborist crew
would prune approximately 3,900 public trees per year for a 7-year pruning cycle, it is likely the
Contract Pruning budget could be reduced and the rate of removals will likely decrease due to
enhanced maintenance. In addition, the Professional Services budget may decrease until
updated services are needed such as an updated public tree inventory and updates to this
management plan. Lastly, the Contract Landscape Watering budget may decrease since it is
recommended the City purchase a watering rig for the in-house arborist crew. With the budgets
listed in the table above, there is an overall budget increase in the amount of $314,507, but as
stated earlier, the amount of increase may be reduced by adjusting budgets of particular line
items.
Program Needs 62 | P a g e
WORKFLOWS AND STANDARD OPERATING PROCEDURES
Consistent protocols are needed for impervious surface conflicts, sidewalks specifically, along
with budgetary considerations. Poor historic tree species selection, the growth of the trees, and
the size of some planting sites has resulted in multiple locations around the City where the
infrastructure conflict is a result of the trees outgrowing their space causing surface upheaval
and basal flare. Currently, neither Urban Forestry nor Public Works has the means in terms of
staffing or resources to deal with replacing all the trees and sidewalks on their own, but the
mandate by the Americans with Disabilities Act (ADA) to eliminate all sidewalk hazards
remains. Updated protocols between Public Works, Parks & Trails crews, and the Urban Forestry
Program are needed where the conflict is addressed using a joint approach. Updated protocols
would require a dedicated fund.
The City of Renton Walkway Program provides for the removal and replacement of existing curb
and gutter, sidewalks, and curb ramps, where such facilities have deteriorated or have been
damaged and is also responsible for new installations. There are many older neighborhoods
with damaged or deteriorated infrastructure or lacking curb ramps up to current ADA
standards. These deficiencies are being addressed by this program to provide safe and
convenient non-motorized facilities for pedestrians but the funding averages $250,000 which
is less than adequate to fully comply with ADA requirements. More recent assessments of
meeting needs for compliance are substantial. Impacts of other infrastructure upgrades, such
as widening lanes for buses, which impact street trees should be more thoughtfully planned
and designed. It is not a sustainable practice to simply remove mature trees and replant on a
one for one basis.
The management practice to actively address hazards within the public right-of-way by
repairing sidewalks and removing and replacing trees as needed is important to provide
mobility throughout the City and maintain canopy cover. Often, root pruning is the main
approach to preserve a tree and fix a sidewalk, but this practice comes with the potential to
impact tree health and tree longevity. If a tree cannot be safely preserved after root pruning, it
requires removal. However, alternative materials and methods are becoming more common to
repair sidewalk issues in lieu of tree removal. New sidewalk materials and technologies can be
used that reinforce the structural integrity of concrete to allow tree roots to grow underneath
sidewalks and increase useful longevity like suspended pavement systems and structural soils.
In some cases, tree planting areas can be expanded to allow more growing space like
meandering sidewalks, bulb-outs, or increased tree well sizes. All of these methods should be
within the solutions “toolbox” before tree removal is allowed, but they are not all currently
codified as available City options and agreed upon by City staff as acceptable City standards.
Therefore, Appendix B, provides the draft framework for tree and sidewalk conflicts and
alternative solutions for the City to consider.
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 63 | P a g e
Recommendations for Tree and Sidewalk Conflicts
The City should formally adopt the decision checklist and protocols provided in Appendix B and
include alternative solutions in design guidelines and standards. Alternative solutions may offer
cost savings in some instances though generally, the City’s Walkway Program is underfunded.
In most Washington cities that are responsible for sidewalk repair and replacement, funding
comes from the General Fund or through a ballot-approved Sales and Use Tax. Sales tax rates
for funding sidewalk programs average 0.2%. In Seattle, the responsibility is placed on the
adjacent property owner but the “Levy to Move Seattle” was approved by voters in 2015 to help
fund sidewalk maintenance and improvement projects. In addition to local funds, Seattle also
seeks state or federal grants. Grant funding may be available for sidewalk repair but is not a
consistent long-term option. One local example of a grant to fund the program is in Sumner
where Sound Transit is funding sidewalk replacements as part of their station access
improvement grant, costing approximately $1.4 million.
Other funding options or mechanisms include special citywide assessments, bonds,
improvement districts, gas tax, or tax incremental financing. In Cheney, a voter-approved tax on
electrical and natural gas services funds maintenance of residential streets and sidewalks. The
4% electric and natural gas tax generates roughly $380,000 annually. Whenever new
development triggers frontage improvements there are opportunities for improved street tree
planting and would be an appropriate time to levy enhanced use fees.
The City should explore these options such as the Sales and Use Tax option if General Funding
is not available to fully cover sidewalk repair and replacement per ADA requirements. The
alternative is to place the responsibility of sidewalk repair and replacement on the adjacent
property owner. This option may not sit well with property owners and would likely require a
permitting system. An example is in Seattle again where it is the property owner’s responsibility
unless the sidewalk damage is caused by City infrastructure such as a City-owned tree or sewer
line. In this scenario, the City takes the responsibility for making the repairs.
Source: City of Renton, WA 2009 Urban and Community Forestry Development Plan
Program Needs 64 | P a g e
TREE CANOPY COVER GOALS
To guide efforts towards the urban forest vision, communities with tree canopy assessment data
often set tree canopy cover goals based on the existing tree canopy cover amount and the aim
to provide an equitable distribution of canopy cover and associated benefits. For Renton, the
planning consultants conducted an analysis of tree canopy cover data and Tree Equity Scores
(TreeEquityScore.org) to develop draft canopy goals that would increase canopy cover and
address tree equity. This section provides the guidance to refine the goals, establish incremental
targets, and formally adopt a Citywide canopy goal that is shared by the City, its partners, and
all property owners within Renton. Progress towards these canopy goals should be tracked,
measured, and shared to guide urban forest management and maintain community interest
and support.
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Canopy Goals – Purpose and Approach
Across the U.S., cities are setting goals— some based on careful study of current canopy,
community needs, and availability of planting space, other base their goals on the principle that
more trees are better than fewer, set ambitious campaign goals, then work to mobilize efforts
to meet it. Generally, the U.S. Forest Service recommends canopy cover of 40-60% in
northwestern communities and in 1997, the American Forests organization established a
benchmark of 40% after analyzing the tree canopy in dozens of cities from 1992 to 1997 and
working closely with the research community. While incredibly valuable and groundbreaking
at the time, technology and research have significantly evolved over the past 20 years, leading
to a consensus that more nuanced approaches to canopy goal setting are necessary. Supporting
this statement, U.S. Forest Service Research Forester Greg McPherson of the Pacific Southwest
Research Station adds, “Tree canopy cover targets are difficult to specify broadly because the
opportunities to create canopy are highly variable among cities, even within a climatic region
or land use class.”
Tree canopy targets are best developed for specific cities and should consider constraints to
creating canopy such as:
❖ Development densities (i.e., dense development patterns with more impervious surfaces
have less opportunity for cover);
❖ Land use patterns (i.e., residential areas may have more opportunity for canopy than
commercial areas, but canopy cover tends to be less in residential areas of disadvantaged
communities versus wealthy ones);
❖ Ordinances (i.e., parking lot shade ordinances promote cover over some impervious
areas); and
❖ Climate (i.e., canopy cover in desert cities is often less than tropical cities).
Within those parameters, quantifiable data can be used so a tree canopy goal achieves specific
objectives, such as reaching the canopy percentage necessary to reduce urban h eat island
temperatures to a specific range, or to reduce stormwater runoff by a projected amount.
According to a national analysis by U.S. Forest Service researchers, a 40-60% urban tree canopy
is attainable under ideal conditions in forested states. 20% in grassland cities and 15% in desert
cities are realistic baseline targets, with higher percentages possible through greater
investment and prioritization.
It is important to note, however, that urban tree canopy percentage is just one of many criteria
to consider. A robust tree canopy comprised of largely invasive species, for example, is not a
healthy urban forest. Age and species diversity, condition of trees and equitable distribution
across income levels, to name a few, should also be considered (Leahy, American Forests, 2017).
Citywide and Zoning Type Tree Canopy Goals
The following presents the proposed canopy goals though the City and partners should
evaluate and refine these for approval by staff and City Council.
For the City of Renton, the development of canopy goals was driven by tree canopy cover data,
benchmarking research, Tree Equity Scores, analysis of existing and potential resources, City
input, and community feedback.
Using this integrated approach, the City of Renton’s ambitious and achievable goal is 33% tree
canopy cover in 20 years (2042), with an intermediate goal of 30% by 2032. To achieve this, the
City must preserve the existing canopy and increase its coverage by four percent, up from 29%,
and plant approximately 950 trees annually or a total of 19,000 trees. These new trees would
collectively grow the canopy throughout the City to an area equivalent to nearly 415 football
fields and would provide additional ecosystem services and benefits in the amount of
Program Needs 66 | P a g e
approximately $215,000 annually. These calculations and estimates are based on industry
research and practices though there are some assumptions including;
❖ A no-net-loss strategy, meaning the number of public trees removed along with
removals on private property or through development are replaced.
❖ Trees that mature into large canopy-bearing trees are planted wherever feasible.
Calculations use an average tree canopy diameter of 40 feet equating to a surface area
of 1,257 square feet.
❖ Includes City-led, partner, volunteer, and private tree plantings. In this study and canopy
goal scenario, it is recommended the City plant 60% of the necessary trees or
approximately 570 trees per year.
❖ The City only has approximately 1,700 public street planting sites available as of the 2021
inventory so new planting sites will need to be created by converting impervious surfaces
to planting sites and/or planting in parks and natural areas.
❖ Assumes a potential for young tree mortality post-planting.
Within the framework of this Urban Forest Management Plan 10-year Update, an intermediate
tree canopy cover goal after year 10 was also drafted. By the end of the year 2032, if the City as
a whole were to plant 525 trees each year for 10 years, a total of 5,250 trees would be planted
resulting in an increase in canopy to 30%, up from 29% currently. Again, using the 60-40 split
regarding tree planting numbers and allocation, the City would plant 3,150 trees in 10 years. The
overall added benefit from City-, partner-, and community-led plantings after year 10 is
estimated at nearly $60,000 annually once the trees are all established. To achieve these goals,
the existing tree canopy must be preserved through policy enforcement, property owner
education, proper tree maintenance, pest and disease management, soil
conservation/protection, and urban forestry oversight on site designs and plans.
The following provides the calculated process of establishing the 20-year canopy goal for
Renton: The amount of tree canopy cover and available planting space was analyzed by City
Zoning Type and Community Planning Area. A percentage of total possible planting area
(vegetative and impervious) to be planted was assigned to each Zoning Type and Community
Planning Area based on the total amount of plantable space, the existing canopy, limitations of
the Zoning Type/Planning Area, available resources, and other City needs. This approach realizes
the unique opportunities, limitations, extent, resources, and characteristics found among
various city zoning classes and planning areas. Canopy goals and planting targets must not be
standardized across the City, they should be specific to the area. This method was applied and
summarized in the following table.
2017 2022 2032 2042
29%
30% 33%
5,250
trees
19,000
trees
Figure 27. Renton's 10-year and 20-year canopy goals
PROPOSED TREE CANOPY COVER GOALS
27%
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 67 | P a g e
Table 22. Long-term tree canopy goals (by 2042) and planting targets by Community Planning Area
Community
Planning Area
Total
Possible
Planting
Area (%)
% of
Total Possible
Planting
Area to be
Planted
Modeled
Canopy %
(% of Total
PPA)
Number
of Trees
to Reach
Goal
Annual
Added (Net)
Eco-
Benefits ($)
Benson 19% 15% 33% 2,868 $32,525
Cedar River 17% 15% 49% 1,094 $12,407
City Center 22% 20% 18% 2,933 $33,262
East Plateau 18% 20% 33% 1,666 $18,891
Highlands 17% 15% 28% 2,470 $28,011
Kennydale 24% 20% 38% 1,795 $20,360
Talbot 26% 20% 44% 2,578 $29,233
Valley 19% 20% 33% 2,570 $29,148
West Hill 33% 20% 38% 877 $9,947
TOTAL 33% 18,852 $213,783
24%
17%
22% 33%
19%
18%
17%
19%
26%
Figure 28. Map displaying the
Possible Planting Area by Community
Planning Area and an example of
PPA planting targets in Highlands
PLANTING TARGETS TO IDENTIFY CANOPY GOALS
Program Needs 68 | P a g e
Priority Planting Areas to Achieve Canopy Goals and Tree Equity
Once the City finalizes local and Citywide tree canopy goals, it is recommended to establish
priority areas based on a variety of themes and community needs. Themes may include
ownership type (public and private), areas of low existing tree canopy, Tree Equity Scores
(TreeEquityScore.org), and greatest amount of available planting space while other themes may
address air quality, stormwater reduction, and water quality. Others may evaluate opportunities
to address disadvantaged areas, densely populated regions, and human health factors such as
asthma cases, median age, and mental health. In any planting prioritization scenario, the scale
may include U.S. Census Bureau Census Block Groups, Zoning Type, Community Planning Areas,
and Citywide.
Using the 2018 Tree Canopy Assessment, the regional TreePlotter CANOPY software application
(pg-cloud.com/KingCD-Cities), and analyses in a Geographic Information System (GIS), a series
of recommended prioritization techniques is provided. The description of the prioritization
techniques and scenarios is provided below followed by a series of corresponding priority maps.
❖ Census Block Groups (CBGs) with the greatest possible planting area. CBGs with the
highest percent of total area available for possible planting. Includes vegetative and
impervious possible planting areas.
❖ CBGs with low amounts of tree canopy cover. CBGs with the lowest percentage of
existing tree canopy cover.
❖ Tree planting in Census Blocks to reduce stormwater runoff. Trees can be integrated to
help manage stormwater, specifically when targeting impervious surfaces. This indicator
uses available planting area on impervious surfaces and available planting areas within
100 feet of all surface water bodies.
❖ Tree planting in neighborhoods with high populations of minorities. Tree canopy is
negatively correlated with the percentage of minority residents. Planting trees in
communities with higher percentages of minority residents can support environmental
equity.
❖ Tree planting in neighborhoods with underserved populations. Tree canopy is positively
correlated with higher median income. Planting trees in lower income communities can
support environmental equity. CBG suitability is based on the percentage of residents
living below the poverty level.
View the maps on the following pages for examples of the listed planting priority techniques.
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 69 | P a g e
Priority Planting Areas: Addressing Available Planting Space
Suitability
Very High
High
Medium
Figure 29. Map displaying the Census Block Groups most suitable for trees due to high possible planting area
Program Needs 70 | P a g e
Figure 30. Map displaying the Census Block Groups with the lowest existing tree canopy cover
Priority Planting Areas: Addressing Low Existing Tree Canopy Cover
Suitability
Very High
High
Medium
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 71 | P a g e
Figure 31. Map displaying Census Block Groups most suitable for tree plantings to address stormwater runoff
Priority Planting Areas: Addressing Stormwater Runoff
Suitability
Very High
High
Medium
Program Needs 72 | P a g e
Figure 32. Map displaying higher concentrations of minority populations for increasing tree canopy cover
Priority Planting Areas: Addressing Tree Cover in Minority Neighborhoods
Suitability
Very High
High
Medium
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 73 | P a g e
Figure 33. Map displaying Census Block Groups with underserved populations for increasing tree canopy cover
Priority Planting Areas: Addressing Tree Cover in Underserved Neighborhoods
Suitability
Very High
High
Medium
Program Needs 74 | P a g e
Recommendations for Tree Canopy Cover Goals
Cities around the world are using tree canopy goals, usually in the form of percent tree canopy
cover, to guide urban forest management and meaningfully improve the livability of their
communities. Urban tree canopy (UTC) is ideal for goal setting because it can represent the
complex distribution and benefits of an urban forest within a single metric. Urban tree canopy
goals must walk a careful line of ambition, inspiration, and practicality.
Measuring, tracking, and improving urban tree canopies is an essential component of
sustainable urban living. As the world’s population continues to urbanize the value of healthy
UTC is only going up. Unfortunately, the global urban canopy trend is moving in the opposite
direction. A worldwide analysis showed urban forest cover on average is slightly, but
significantly decreasing. The United States is also losing urban tree canopy, to the tune of
175,000 acres or 36 million trees a year. That represents a loss of $96 million in tree benefits a
year, and those benefits, like heat reduction and public health improvements, are growing in
necessity.
Urban tree canopies are in perpetual motion as growth and regeneration push against
destructive forces, both natural and anthropogenic. These include development expansion, old
age, disease, pests, and fire. Reversing this course starts with knowing the extent of the urban
tree canopy and then establishing a goal for growth. “By knowing the amount of and direction
in which urban tree cover is moving, urban forest management plans can be developed to
provide desired levels of urban tree cover and forest benefits for current and future generations.”
(Nowak, et al. 2018)
For Renton, before setting and adopting a tree canopy cover goal, the current coverage must
be understood using the latest Urban Tree Canopy assessment. The 2018 UTC assessment
provides the baseline data for the urban forestry consultants and the City to establish
recommended canopy goals and tree planting priorities or targets.
Based on the assessment data, City input, community feedback, and benchmarking research
the recommended tree canopy goals for the City of Renton are provided in the following table:
Table 23. Summary of the recommended tree canopy goals and planting targets for Renton
Goal
Metric
Current Canopy
(2017)
Short-Term
Canopy Goal
Long-Term
Canopy Goal
Canopy % 29% 30% 33%
Goal Year -- 2032 2042 Total Trees to Reach Goal City-Led -- 3,150 11,400
Public-Led -- 2,100 7,600
Total Trees -- 5,250 19,000 Total Trees per Year to Reach Goal City-Led -- 315 570
Public-Led -- 210 380
Total Trees per Year -- 525 950
Future Added Benefits -- $60,000 $215,000
UTC assessments should be a periodic process and research recommends conducted follow up
assessments every 5 to 8 years to track canopy change, assess performance, and adapt priorities
to changing needs and budgets. Tree planting priority areas should be revisited annually and
informed by the public, new data, analysis, available resources, and other factors.
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TREE PLANTING INITIATIVE
Tree planting is critical to the health and longevity of Renton’s urban forest. However, tree
planting should be methodically planned with a specific purpose in mind. One of the best ways
to do this is to define and adopt an official planting initiative guided by a planting strategy. The
first step in developing a planting strategy is to define the goals. Often times, this goal aligns
with a citywide tree canopy cover goal and the timeframe to achieve it.
An effective tree planting initiative and program address three main questions: where to plant,
what to plant, and how to plant? It is important to develop an overall planting strategy where
the initial planting efforts are concentrated on streets and areas with the greatest need for
improvement. Tree species and planting location designations are significant components of a
municipal tree care program because of the long-term impact of these decisions. Success of a
continuing tree planting program will be judged by the health of the trees after planting and
the amount of money spent on planting and maintaining the new trees. With a small amount
of planning, healthy trees with greater life expectancy can be established with minimal up-front
investment and relatively minor maintenance costs.
This Tree Planting Initiative provides guidelines for the implementation of an organized and
comprehensive tree planting strategy that results in the prioritization of tree planting locations
and the expansion of Renton’s urban tree canopy within the confines of available resources.
Information on suitable planting locations in the City is provided in the previous section and
general recommendations on choosing suitable trees for each site follow.
Where to Plant
There are numerous opportunities to plant more trees on public property in the City of Renton.
Historically, the locations of new tree plantings on City-owned rights-of-way in Renton have
been based on constituent requests, the replacement of dead or dying trees (where feasible),
and project-specific plantings (e.g., streetscape improvement projects). With the updated tree
inventory, City managers now also know the exact location of additional planting sites that are
available throughout the City. Renton’s street and park tree inventory includes 1,789 available
planting sites as of January 2021. Moreover, the development of a prioritization scheme based
on canopy data allows the City to begin significant tree planting efforts in high priority areas of
the City.
According to the January 2021 inventory analysis report, the current stocking level is 93.5%,
based on a total 27,561 suitable planting sites, including 25,772 trees, 1,315 vacant sites, and 474
stumps. “Stocking” is a traditional forestry term used to measure the density and distribution of
trees. In this case it means that, of the total number of available planting sites identified in the
tree inventory along the public right-of-way, 93.5% currently have a tree present. Note that this
value only considers the currently available planting areas along the street right-of-way, and not
impervious surfaces that could become planting locations. Moreover, this value does not
incorporate potential planting locations in parks or other civic spaces. Of the total public trees
in the inventory, 724 trees were recommended for removal (in 2021 inventory analysis report).
These recommended removals represent a future increase in total number of potential planting
sites. An important benchmark in maintaining a sustainable urban forest is to keep it at least
90% stocked, such that no more than 10% of the existing planting sites remain vacant. The City
should make every effort to budget for tree planting in the future to maintain the urban forest
at least 90% stocked and to continue increasing its canopy.
Planting locations throughout the City were identified and prioritized as part of the urban tree
canopy analysis (Priority Planting Areas to Achieve Canopy Goals and Tree Equity Section).
Potential planting locations included all viable areas of the City that were classified as
grass/open space, impervious (parking lots), and bare ground in the urban tree canopy analysis.
Program Needs 76 | P a g e
Tree Planting Parameters
Trees are an important part of the City, but they must coexist with various other aspects of the
built environment. To provide ample space for a growing tree while also maintaining public
safety and protecting other City infrastructure, the City should use the following minimum
guidelines when choosing new planting locations:
❖ New tree wells in existing sidewalks provide a minimum of 18 square feet of open soil (ex.
a 3’ x 6’ tree well).
❖ New tree wells in new sidewalks should provide a minimum of 36 square feet of open
soil (ex. a 6’ x 6’ tree well), and at least 1,000 gross cubic feet of soil value space for each
tree, providing any soil volume under paved surfaces through suspended pavements or
structural cells.
❖ To reduce infrastructure conflicts and maintain visibility and access to important public
safety features, trees should be planted a minimum of:
o 20 feet away from any intersection, crosswalk, or stop sign;
o 5 feet away from any fire hydrant or utility pole;
o 10 feet from any streetlight;
o 3 feet from any driveway or walkway; and
o 1 foot away from any underground utilities (ex. gas and water).
o The width of the sidewalk must also be taken into account, as per American with
Disabilities Act (ADA) regulations a 3 foot sidewalk width must remain.
o Trees must be spaced out in such a way that they have room to grow. Trees are
spaced at least 20 feet on center (i.e., measured trunk to trunk).
What to Plant
The City must determine which tree species will be planted in each specific site. The phrase
“right tree, right place” is the most important concept in planting. Many factors must be
considered in choosing a species for a site that maximizes the health and survivability of the
tree, and the benefits provided by that tree. Trees in urban environments must withstand
particularly challenging conditions, such as high temperatures, drought, flooding, air pollution,
soil salt, and limited growing space both above and below ground. Trees have different
characteristics suitable for different landscapes, sites, and microclimates. It is recommended
that all characteristics be recognized, including, but not limited to, the desired function (e.g.,
seasonal flowering, shade canopy, wind resistance), mature size and shape for the intended
location, soil conditions, root structure, maintenance requirements, potential pest problems,
and survivability in the face of climate change. Equally important to selecting the right tree is
choosing the right spot to plant it. Blocking an unsightly view or creating shade may be a
priority, but it is important to also consider how a tree may impact existing structures and
utilities as it grows taller, wider, and deeper. For example, if the tree’s canopy, at maturity, will
reach overhead utility lines, it is best to choose another tree or a different location. Taking the
time to consider location before planting can prevent power disturbances and improper utility
pruning practices.
Historically, there has been some mismatch of tree species selection with available planting
sites in Renton. There are some large growing trees under power lines, and there are some small
growing trees planted in sites suitable for larger trees. Large trees in small spaces can damage
sidewalks and curbs, require severe pruning for overhead utility lines and street clearance, and
often have a much shorter service life due to the restricted growing area. Small trees in large
spaces limit the use of mature shade trees on public streets. It is well known that larger growing
trees provide the most environmental and economic benefits, and appropriate areas to plant
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 77 | P a g e
them rarely exist in older, well developed communities. Proactive planning should be made to
plant the “right tree in the right place” in the vacant sites, considering available growing space,
presence of utilities, and traffic and pedestrian clearance issues, while obtaining the desired
aesthetic effects and function of the street tree. Planting the proper type of tree for each
planting area will result in a more effective, healthy, and attractive urban forest.
Tree Species Diversity
At the scale of the entire urban forest, species diversity in new plantings should be of major
importance. Planting a variety of species can decrease the impact of species-specific pests and
diseases by limiting the number of susceptible trees in a population. Moreover, planting a wide
variety of tree species can help limit the impacts from physical events, as different tree species
react differently to stress. Species diversity helps withstand urban forest impacts from drought,
ice, flooding, strong storms, and wind. As stated in the Structure of the Public Tree Population
section, at the genus level, maples (Acer) account for 27% of the total public tree population
and bigleaf maples and Douglas-firs exceed the 10% threshold with 15% and 11% respectively.
The dangers of planting monocultures have proven to be devastating. One of Renton’s goals
should be to increase species diversity throughout the City, such that no species represents
more than 10% and that no one genus comprises more than 20% of the population.
Consideration should be given to large trees that provide shade, are aesthetically pleasing, and
provide food or habitat for native insects and wildlife. Although the City should consider
focusing efforts on planting species that are native to the region, particularly in the face of
climate change, the wider effort should focus on urban-tolerant and/or wind-resistant species,
regardless of origin.
Tree Species Selection
Matching a species to its favored climatic and soil conditions is the most important task when
planning for a maintainable and survivable landscape. Plants that are well matched to their
environmental conditions are much more likely to resist pathogens, insect pests, and severe
storm damage and will therefore require less maintenance overall and be more likely to survive.
In addition to considering site characteristics (such as climate, precipitation, native vegetation,
availability of space) and soil characteristics (such as soil texture, structure, drainage, pH, water
availability, and road salt), specific physical tree features must also be scrutinized to ensure
public safety. Some considerations for street trees are the amount of litter dropped by mature
trees, the maintenance required, and public acceptance.
In the face of climate change, plummeting insect popu lations, and mass extinctions, the City
should focus efforts on planting species indigenous to the region. Planting species that are
native to the region whenever possible will provide additional benefits to the ecosystem at
large. Above all, given the tough growing conditions in an urban environment, tree species
should be selected for their durability and low maintenance requirements. These attributes are
highly dependent on site characteristics as well as species characteristics.
How to Plant
The steps taken to properly plant trees must continue to be clearly outlined for City crews and/or
contractors performing the work. Planting oversight and/or post planting inspections must
continue to be performed to ensure that the work meets the guidelines set fort h by the City.
The tree planting methodology outlined in this section is supported by industry standards and
best practices, including the American National Standards Institute (ANSI) Z60.1-2014 American
Standard for Nursery Stock, and the American National Standards Institute (ANSI): Standard
A300. Standard Practices for Tree, Shrub and other Woody Plant Maintenance.
These standards and best practices detail the methods and protocols for selecting healthy
planting stock, handling trees during transport and planting, preparing the planting site,
planting the tree, mulching, and young tree pruning.
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Key Considerations for a Tree Planting Plan
A planting strategy is crucial to urban forest sustainability and should be based on data,
available resources, partnerships, and community input. Some of the more common goals that
define a planting strategy include:
❖ Equitable Distribution. With this goal, planting priorities are assigned to areas
determined to be the most in need based on the goal of an even distribution of benefits
provided by trees. Beyond equal distribution, an area defined to be "in -need" is
determined locally and can be a combination of priorities or focused on one specific
priority. It is recommended the City utilize the guidance provided in the Tre e Canopy
Cover Goals section to identify areas of low tree equity that are most suitable for planting.
❖ Areas of Predicted Future Canopy Loss. Older neighborhoods with a more established
tree canopy can anticipate significant losses in future years. One met hod to planning
future planting efforts is to target these replanting areas now to aid in a less drastic
succession of trees over time.
❖ Benefits-Based Plantings. Areas that have a specific issue like poor air or water quality,
or a large percentage of older residents sensitive to heat stress, may work to plant trees
based on the anticipated benefits in years to come.
❖ Regular, Methodical Planting in Concert with Cyclical Tree Care Efforts. Planting may
be most effective if it follows the City’s inventory, in that trees are planted where they are
removed. Regular methodical planting can also be considered a worthy goal.
❖ Species Diversity. Planting strategies should not only identify where to plant but also
what is being planted. Species diversity in Renton can quickly become an issue if data is
not used to make decisions on the types of trees to plant. Neighborhood -level and
Citywide planting plans should detail how biodiversity will be maintained with short-
and long-term strategies.
❖ Inventory-Driven Plantings. In addition to tree canopy assessment data or data
pertaining to the spatial location of existing tree canopy and possible planting space, a
city may also utilize or conduct inventories of available public planting spaces. Often
times, these types of inventories identify planting spaces based on criteria such as
minimum width, distance from existing tree, distance from intersection, among others.
Most planting space inventories catalogue the relative size of the growing space (small,
medium, large).
❖ Partners in Planting. Renton’s planting strategy should also include who is doing the
planting. This work can be done by City partners, neighborhood groups, community tree
stewards, developers, and other interested parties, thus allowing the City to focus on
specialized care (pruning, removals, assessments).
Future tree plantings should focus on maintaining or increasing species diversity and reducing
reliance on any particular species.
Renton’s public tree population is primarily in fair or better condition with over 280 distinct
species. The City should continue to focus resources on preserving existing and mature trees to
promote health, strong structure, and tree longevity. Structural and training pruning for young
trees will maximize the value of this resource, reduce long-term maintenance costs, reduce risk,
reduce storm damage, and ensure that as trees mature, they provide the greatest possible
benefits over time.
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Tree Planting Recommendations
• Increase genus and species diversity in new and replacement tree plantings to reduce
reliance on abundant groups. At a minimum, strive for no species representing more
than 10% of the overall population and no genus representing more than 20% of the
overall population.
• Use available planting sites to improve diversity, increase benefits, and further distribute
the age distribution of street and park trees.
• Prioritize planting replacement trees for those trees that have previously been removed.
• Identify additional planting sites for trees and use the largest stature tree possible where
space allows.
• Prioritize successional planting of important species, as determined by relative
performance index (RPI) and the relative age distribution.
• Species that are adequately represented by established age distributions but lack recent
plantings should receive priority care.
• Prioritize structural pruning for young trees and ensure maintenance plans and
associated budgets are prepared as trees become established.
• Regularly inspect trees to identify and mitigate structural and correctable defects to
reduce the likelihood of tree and branch failure.
• Consider opportunities to further support wildlife habitat and pollinators when making
decisions on the species of tree(s) to plant.
• Create or update a recommended master tree list for City projects and to provide as a
recommendation to the public for private property plantings. Include attributes such as
tree size at maturity, primary feature, soil requirements, space requirements,
recommended location(s), native/nonnative classification, description, and any concerns.
• Consider preparedness planning for invasive pests and deleterious effects of climate
change including wildfire, stormwater, and extreme weather events.
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POST-PLANTING CARE AND YOUNG TREE MAINTENANCE
The urban forest within Renton plays a significant role in maintaining the health and vitality of
urban life. It provides a wealth of benefits to neighborhoods and residents through the
reduction of energy consumption, the removal of pollutants from the ai r and water, reduction
in stormwater flows, increased valuation of private property, increased worker productivity,
reduction in stress and violent crime, as well as providing recreational opportunities and
aesthetic diversity. At the same time stresses from the urban environment including air
pollution, damage by vehicles, increased impervious surface, soil compaction, and maintenance
neglect reduce the diversity and magnitude of these benefits and may lead to tree-related
problems.
The inherently close interaction between people and trees in the City requires active and
diligent management of the urban and community tree and forest resources to ensure public
safety. To enhance tree canopy and associated benefits, trees need to be properly planted and
maintained.
The City of Renton can use the following information to make any updates to tree policies.
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Tree Maintenance Best Practices
The following provides an overview of tree maintenance best practices. It is not intended to be
an extensive or comprehensive summary of best practices. All tree maintenance practices
should follow the American National Standards Institute’s (ANSI) A300 Standards (Parts 1-10).
Reasons for Tree Pruning
1. Pruning for Safety
Involves removing branches that could fall and cause injury or property damage, trimming
branches that interfere with lines of sight on streets or driveways, and removing branches
that grow into utility lines. Safety pruning can be largely avoided by caref ully choosing
species that will not grow beyond the space available to them and have strength and form
characteristics that are suited to the site.
2. Pruning for Health
Involves removing diseased or insect‐infested wood, thinning the crown to increase airf low
and reduce some pest problems, and removing crossing and rubbing branches. Pruning can
best be used to encourage trees to develop a strong structure and reduce the likelihood of
damage during severe weather. Removing broken or damaged limbs encourages wound
closure.
3. Pruning for Form
Improves the structure of trees and removes branches that are more likely to fail. Branches
that are poorly attached may be broken off by wind and accumulation of snow and ice.
Branches removed by such natural forces often result in large, ragged wounds that rarely
seal.
4. Pruning for Aesthetics
Involves enhancing the natural form and character of trees or stimulating flower production.
To reduce the need for pruning it is best to consider a tree’s natural form. It is very difficult
to impose an unnatural form on a tree without a commitment to constant care.
Common Types of Tree Pruning
1. Crown Cleaning
Consists of the selective removal of dead, dying, diseased, and weak branches from a tree’s
crown. No more than 25% of the live crown should be removed in any one year, even for
young trees.
2. Crown Thinning
Primarily for hardwoods, thinning is the selective removal of branches to increase light
penetration and air movement throughout the crown of a tree. The intent is to maintain or
develop a tree’s structure and form. To avoid unnecessary stress and prevent excessive
production of epicormic sprouts, no more than one‐quarter of the living crown should be
removed at a time. If it is necessary to remove more, it should be done over successive years.
Branches with strong U‐shaped angles of attachment should be retained. Branches with
narrow, V‐shaped angles of attachment often form included bark and should be removed.
3. Crown Raising
The practice of removing branches from the bottom of the crown of a tree to provide
clearance for pedestrians, vehicles, buildings, lines of site, or to develop a clear stem for
timber production. After pruning, the ratio of the living crown to total tree height should be
at least two‐thirds. On young trees temporary branches may be retained along the stem to
encourage taper and protect trees from vandalism and sunscald.
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4. Crown Reduction
Most often used when a tree has grown too large for its permitted space. This method,
sometimes called drop crotch pruning, is preferred to topping because it results in a more
natural appearance, increases the time before pruning is needed again, and minimizes
stress (see drop crotch cuts in the next section). Crown reduction pruning, a method of last
resort, often results in large pruning wounds.
Figure 34. Examples of the types of tree pruning
Tree Pruning Cuts
Pruning cuts should be made so that only branch tissue is removed and stem tissue is not
damaged. To find the proper place to cut a branch, look for the branch collar that grows from
the stem tissue at the underside of the base of the branch. On the upper surface, there is usually
a branch bark ridge that runs parallel to the branch angle, along the stem of the tree. A proper
pruning cut does not damage either the branch bark ridge or the branch collar. A proper cut
begins just outside the branch bark ridge and angles down away from the stem of the tree,
avoiding injury to the branch collar.
Image source: Arbor Day Foundation
Image source: Pennsylvania State University Urban Forestry Extension
Figure 35. Types of pruning cuts and the proper branch cutting technique
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Utility Tree Maintenance Best Practices
Utility Tree Pruning Overview
The City should work with the utility companies to ensure proper pruning practices are followed
and that open communication between the company, the city, and the public are maintained.
The International Society of Arboriculture provides guidelines for maintaining trees near power
lines (Best Management Practices – Utility Pruning of Trees, G. Kempter).
Maintaining power lines free of tree growth is based on a consistent, planned trimming cycle of
the utility vegetation management company. This approach improves electric service to all the
customers who get their power from that line. A sensible approach to trimming trees means
having a thorough maintenance plan that improves the safety and reliability of electric service
to residents. Residents and the City staff should not attempt to trim any vegetation growing
near or on any overhead power lines.
Utility Tree Maintenance Techniques
1. Directional Pruning
Removes entire branches and limbs to the main trunk of the tree and future growth is
directed away from the power lines. Reduction cuts are used for removing these branches
and limbs and should be pruned properly back to a lateral branch that is at least one-third
the diameter of the branch being removed. This allows for good wound closure and protects
apical dominance and reduces sprouts.
Avoid topping or rounding over trees. This removes more foliage than directional pruning,
increases the number of tree wounds, stresses the tree, causes unstable decay, and increases
water sprouts.
2. Right Tree Right Place
Selecting the right tree for the site can reduce potential safety hazards and improve the
reliability of the electric service. Smaller trees near power lines do not need to be excessively
pruned and do not lose their natural form.
3. Recommended Trees
Trees potentially suitable for planting adjacent to power lines should be shorter and slow
growing to prevent clearance issues.
Photo source: Pennsylvania State University Urban Forestry Extension
Figure 36. Example of trees directionally pruned for clearance from power lines
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Young Tree Maintenance Best Practices
Proper pruning is essential in developing a tree with a strong structure and desirable form. Trees
that receive the appropriate pruning measures while they are young will require less corrective
pruning as they mature.
Young Tree Maintenance Techniques
1. Consider the Nature Form and Desired Growth
Accentuate the natural branching habit of a tree and correct any structural problems over
time, if needed, to not stress the tree.
2. Pruning in 1-2 Years after Planting
Prune as little as possible after planting to ensure there are enough temporary branches to
produce food for new growth of roots, trunk, and branches. Prune only dead, broken,
malformed, or diseased branches. Remove codominant leaders to maintain one dominant
trunk. Prune for clearance if absolutely necessary. Keep size of branch removed to less than
one inch in diameter.
3. Pruning 2-3 Years after Planting
Prune any dead, broken, malformed, or diseased branches. Remove any suckers from the
base of the tree. Next, determine the permanent branch structure by considering:
• Remove, thin, or cut back any competing leaders
• Remove crossing or rubbing branches, keep the branch that maintains the natural form
• Thin excessively crowded branches but do not lions-tail
• Remove branches with narrow angles between the branch and trunk (consider species)
• Remove branches to maintain well-spaced branches along the trunk. Ideal mature trees
will have lateral branches that are 18-24 inches apart (depending on species)
• Avoid pruning near time of bud break
• Prune flowering trees after flowering
1. Prune competing leader
2. Prune malformed branches
3. Remove crossing branches
4. Remove water sprouts
5. Remove branches with poor angles
6. Prune broken or damaged branches
7. Prune temporary branches over time
8. Remove suckers
9. Apply 2-3” of mulch
Photo source: Pennsylvania State University Urban Forestry Extension
Figure 37. Example of branches to be pruned for newly planted trees to promote good structure
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Tree Planting Best Practices
The following provides an overview of best practices that should be considered and followed
before during and after planting trees.
• Trees to be planted should be selected from an approved tree planting list developed to
maintain and enhance species diversity that are suitable for the Renton, WA Plant
Hardiness Zone and changing climates.
• Planting material will conform to the latest version of the American Standard for Nursery
Stock (American National Standards Institute [ANSI] Z60.1). Trees to be planted should
be of standard quality or better, and should be true to name and type of their species
variety.
• Trees should not be planted in tree lawns less than 2 feet in width or in planting pits less
than 5 feet long by 5 feet wide.
• Trees should not be planted within 50 feet of any major intersection, or within 20 feet of
a fire hydrant, a driveway, or a pole supporting a light.
• The burlap and twine from balled-and-burlap trees should be removed from the tree and
the tree pit. Wire tree baskets may remain on the root ball, but the top one-third should
be clipped and removed from the planting hole.
• Mulch should be placed around trees in a minimum 3-foot circle and 3-inch depth to
protect trees from lawnmower damage and competition from turf; mulch will be kept
away from tree trunks.
• Newly planted trees should be irrigated weekly during droug hts in the growing season
for three years.
Tree Irrigation Considerations and Best Practices:
• Current limiting factor is budget for watering newly planted trees.
• With dry and increasingly hot summers this is a critical requirement for new tree
establishment.
• Establishing new trees requires 4-5 years of supplemental irrigation during the summer
months.
• 400 trees currently (2021) costs $100,000, so every 100 new trees planted requires an
additional $25,000.
• Development of a certain size or where frontage improvements trigger tree planting
should be required to install permanent in-ground irrigation systems.
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FUNDING MECHANISMS
Urban forests are an essential component of a municipality’s infrastructure. Well-managed
urban forests boost community livability and build resilience through a myriad of ecosystem
services. However, the budgets afforded to urban forestry programs do not always represent this
“essential” status and forestry managers often need to work with budgets that are below the ir
needs. Urban forestry budgets are also prone to large swings in need, as is currently being
observed with the emerald ash borer causing spikes in tree removal demand. It can also be
difficult to finance singular, capital intensive projects, like a public tree inventory, that provide
critical data for forest planning and management.
The general fund has long been the core of urban forestry program funding across the county
and it remains a stable and popular option today (making up 72% of urban forestry funding in
2014).
The general fund is also beholden to many other community needs and it is often stretched
thin to meet all these demands. The best strategy for overcoming these budgetary challenges
is to leverage a variety of sources, both public and private, to supplement allocations from the
general fund. A diverse portfolio of funding streams allows urban forestry programs to weather
resource restrictions and provide higher levels of service, like advancing from reactive to
proactive maintenance cycles and implementing the Urban Forest Management Plan.
Street Tree Fund
According to section 9-13-8.B.3 Tree Removal of Renton’s Municipal Code, in lieu of planting
replacement trees, and at the sole discretion of the City arborist, the permittee for a tree removal
request may contribute to the City’s tree fund a dollar amount equal to the value of the
replacement trees, including installation costs. These fees along with Routine Vegetation
Management Permit fees ($105 plus a 3% technology fee), building permit fees received, tree
removal mitigation fees, and stormwater fees could all contribute to a general tree
maintenance operating fund..
Stormwater Utility
Stormwater management has been a growing financial burden for many communities across
the country, even before the effects of climate change have begun to take hold. To pay for the
increasing costs, cities have been implementing user fees for stormwater management services.
These charges are called stormwater fees or stormwater utility fees because they are modeled
after the way municipalities have historically billed residents for other utility services like water
and sewer. Stormwater fees provide local governments with a stable source of revenue to pay
for their growing stormwater management costs, Urban forests are a well-documented
complement to grey infrastructure for treating and mitigating stormwater. Therefore, many
communities include urban forestry in stormwater fee payouts. Stormwater taxes that are
assessed based on a property’s impervious surface area also provide additional motivation for
owners to plant and maintain trees to minimize their fees or receive credits to their utility bill.
Requirements for a Comprehensive Street Tree Program
Different communities use different methods to calculate what to charge for the storm water
services they provide. Due to the complexity of creating a stormwater utility structure that is
outside of the scope of urban forest management planning, the following explanation provides
a simplified overview of a common fee calculation process that addresses the most important
elements other methods share.
Many stormwater fees are based on the amount of impervious cover a property contains. Roofs,
driveways, patios, and parking lots all usually count towards the total, but public sidewalks and
roadways are not factored in. Properties with more impervious cover generate more stormwater
runoff which puts a greater demand on the municipal stormwater system, compared to
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properties with less impervious cover. Because properties with lots of impervious surface
require more stormwater service, they pay larger stormwater fees.
Municipalities use different approaches to estimate the impervious cover on each of the
residential, commercial, and institutional properties their stormwater management system
serves. In some instances, they will visit properties to take measurements in the field but, more
often, they use aerial imagery and computer software to calculate coverages using in-house
information technology staff or consultants. Municipalities often calculate a representative
value to represent the runoff from their residential properties. They do this by carefully
measuring the impervious cover from a sample of typical single-family residential parcels to
determine a median area measured in square feet. This value is called an ERU, short for
Equivalent Residential Unit.
The ERU essentially represents a base billing unit. Properties with very little impervious cover
may be charged some fraction of an ERU, whereas properties with lots of impervious cover may
be charged multiple ERUs. Municipalities take many factors into account when setting their
base ERU billing rate, but the basic process involves two steps:
1. Adding up the impervious cover totals for each of the properties in their community and
dividing this number by the ERU size they calculated earlier to determine the total
number of ERUs in their service area and then,
2. Dividing their estimated annual stormwater budget by the total number of ERUs to
reveal how much they need to charge per ERU to cover their annual stormwater costs.
The nationwide average stormwater fee for single-family residential properties is
currently $5.85 monthly (Campbell, 2019).
The national average stormwater utility fee for single-family residential properties is based on a
2019 survey of 1,716 stormwater utility programs across 40 U.S. stat es and the District of
Columbia. As of 2016, there are a total of 122 municipalities in the State of Washington that have
a stormwater utility (Campbell, 2019).
The City of Renton has an established stormwater utility and bills properties stormwater fees
based on their land use and level of imperviousness. Whether a portion of the annual amount
received therein could be used for funding part of the Urban Forestry program might be worth
exploring. Tree planting, tree maintenance, and plant health care all contribute to sustaining
and enhancing tree canopy cover in the City— which research shows tree canopy reduces
stormwater runoff volume in communities.
Special Assessment Districts
Many properties in Renton are included in unique special financing districts of different types,
especially in newer or redeveloping areas of the City. These districts are ordinarily initiated by
the developer of a property, but are approved by City Council. The purposes of these districts
may include financing of public improvements, ongoing maintenance and operations, or a
combination. In general, these districts either serve to reimburse the developer for public
improvements they are required to provide or to augment public faci lities and services which
might not otherwise be available to most City residents. Most districts obtain their revenue via
a property tax, although some may also charge fees or collect assessments. Residential districts
have an eventual time limit for debt service, but in some cases they may operate more or less
in perpetuity to provide maintenance and/or services.
In Renton, several special assessment districts may be considered, including Business
Improvement Districts (BIDs), General Improvement Districts (GIDs), Special Improvement
Maintenance Districts (SIMDs), and Local Improvement Districts (LIDs). Others include water
districts, fire protection districts, sanitation districts, and parks and recreation districts.
Program Needs 88 | P a g e
Focusing on areas with higher concentrations of street trees or maintenance needs, such as
business districts, may capture property owners who are more willing to pay for tree care. This
approach may be more politically palatable and could potentially lead to a citywide special
assessment district where existing districts could be consolidated and organized into separate
benefit zones, each with its own budget.
Requirements for a Comprehensive Street Tree Program
Special assessments are usually calculated per linear foot, based on the idea that benefits to
property owners are directly related to street frontage. In some cases, special assessments
include additional metrics such as building and/or lot square footage to account for the added
benefit associated with larger buildings that have more occupants.
Parcel Tax
A parcel tax is a special tax levied for the provision of special benefits. Revenues from special
taxes must be used for the specific purpose for which they are intended, so a parcel tax would
create a dedicated funding stream for street trees. Similar to a special assessment, a parcel tax
cannot be based on the value of property; however, the amount levied on each parcel does not
need to be directly related to the benefits provided. Cities have the flexibility to levy parcel taxes
as they see fit, but they are typically based on lot square footage or levied as a flat tax, with the
same amount per parcel.
Parcel taxes are designed to encompass entire cities and therefore, are good candidates for a
citywide street tree program, as opposed to the district-level approach that often occurs under
special assessments. Parcel taxes typically fund more than just street trees. For example, a tree
maintenance tax per parcel may include provisions for the maintenance of parks and open
space and improvements to recreation facilities.
A parcel tax requires strong public support, as it must be approved by voters, rather than just
the majority of property owners, as with a special assessment. Because a parcel tax must be
voted on in a general election, rather than via mail-in ballot, it is likely to receive heightened
political attention. However, general elections capture the votes of renters, who may be more
apt to approve a tax borne by property owners.
Requirements for a Comprehensive Street Tree Program
A parcel tax for urban forestry operations and maintenance (O&M) may be levied as a flat tax, or
it may be based on lot size (square footage). This study evaluated the parcel tax amount
required to finance a City-operated street tree program according to both approaches.
Renton currently has approximately 27,276 parcels Citywide. In the case of a flat parcel tax, the
City would need to levy approximately $28 per parcel per year to cover the full costs of the
public tree maintenance program that follows a 7-year pruning cycle. To fund the tree
maintenance and the in-house arborist crew, a flat parcel tax of approximately $44 per parcel
per year is required.
Renton’s parcels total approximately 660 million square feet. To annually fund the public tree
maintenance 7-year pruning cycle, a parcel tax levied according to lot size would translate to
an annual tax of $0.00117 per square foot and $0.00182 to fund the tree maintenance and in-
house arborist crew annually. For a typical 2,500-square foot lot (25 feet wide and 100 feet
deep), a parcel tax based on lot size would amount to $2.93 to fund tree maintenance annually
or $4.55 to fund annual tree maintenance and the in-house arborist crew.
Another approach to consider is the average parcel lot area of 24,128 square feet ($28.22 - $43.91
per year) or classifications of parcels by counts within area (square feet) ranges.
Considerations and adjustments to these numbers must be made for properties with multiple
right-of-way trees, HOA-managed trees, and maintenance responsibility stated in plat plans.
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Table 24. Parcel tax options and provisions for Renton's Urban Forestry Program
Metric
Annual Tree
Maintenance for 7-
Year Cycle
Tree Maintenance and In-
House Arborist Crew
# of Parcels 27,276 27,276
Recommended Budget $774,000 $1,199,682
Flat Tax (budget by parcel) $28 $44
Parcel Square Feet (sq. ft.) 656,665,036 656,665,036
Tax by Lot Size $0.00117 $0.00182
Typical Parcel (2,500 sq. ft.) Annual Tax $2.93 $4.55
Average Parcel Size (sq. ft.) 24,128 24,128
Average Parcel Size Annual Tax $28.22 $43.91
General Obligation Bonds
Local governments commonly use General Obligation (GO) bonds to fund the construction and
improvement of projects involving real property (e.g., buildings, infrastructure and parks). GO
bonds typically carry low interest rates, making them attractive for capital projects, which may
include tree planting. However, funding is available for discrete projects, often over a limited
time rather than an extended period. In addition, ongoing maintenance is ineligible for GO
bond funding pursuant to federal tax law. Washington cities may pay debt service from GO
bonds through property taxes (in proportion to the estimated value of the goods or transaction
concerned), where assessments are based on property value. As a result, the issuance of GO
bonds requires majority voter approval.
GO bonds may be a tool for financing the planting of street trees in Renton as part of a larger
package of capital improvements, as bonds are typically issued for large amounts. For example,
voters may approve a Road Repair and Street Safety Bond, with funds designated for
streetscape and street safety improvements that included street tree planting. GO bonds may
include tree planting among streetscape improvements through street enhancement
programs such as “complete streets” programs. However, these bonds may allocate funding for
street tree planting to the streets program, rather than the City’s Urban Forestry Program. A
bond specifically focused on a major street tree planting effort may be appropriate in the future.
Requirements for a Comprehensive Street Tree Program
Because GO bonds only fund capital costs, they could only be used to finance tree planting and
establishment activities under a comprehensive city-operated street tree program.
Additional Financing Options
Parking Benefit District
Parking Benefit Districts (PBDs) generate revenue within a special district for improvements and
services related to streets, streetscapes, and landscapes. Because revenue derives from parking
meters, visitors to PBDs fund the majority of improvements. As a result, local governments may
create PBDs via ordinance without requiring a vote of property owners, setting them apart from
other special assessment districts. Although only commercial areas with parking meters
provide revenue, improvements may be implemented beyond PBD boundaries. The ordinance
that creates the PBD determines the share of revenue that must be applied to improvements
within the district, known as the “local return” portion. A committee of residents, property
owners, and business owners advises the local agency administering the PBD on how to expend
revenue. Adjustments to City policy regarding the agency receiving excess meter revenue may
be required to enable the use of this financing option for a street tree program.
While activities may include street tree planting and maintenance, a PBD is likely to cover other
improvements related to neighborhood beautification. It is possible to create a dedicated
Program Needs 90 | P a g e
funding stream for improvements, including street tree planting, sidewalk m aintenance, and
the installation of street furniture and light fixtures. This may present an opportunity to finance
a portion of Renton’s public tree maintenance costs; however, this strategy requires additional
analysis to determine the likely amount of revenue to be generated for street trees, along with
the potential for adding parking meters in new areas of the City.
General Fund
Renton’s General Fund has historically funded a share of street tree planting, establishment,
and maintenance activities through the Capital Improvement Plan (CIP). However,
appropriations have not kept pace with the needs of urban forest management to keep it
sustainable. Because the General Fund is not a dedicated funding stream with a consistent
budget amount, and is subject to changing economic conditions and political support, the
General Fund is a volatile funding source. Nonessential services are the first target for cuts when
expenditures exceed revenues, and there is no guarantee that one year’s appropriations will
equal the next, as the City’s current funding for public trees demonstrates. Given the current
status, reliance on Renton’s General Fund is not ideal for long-term planning of a program that
will require a substantial commitment of resources (e.g., new staff, funding for partners).
A mixed General Fund and Special Assessment model is often considered an appropriate
compromise but can lead to decreases in General Fund budget allocations over time, as the
assessment bears a large share of the burden of maintenance.
Partnerships
A number of opportunities for partnerships exist to help implement a public tree program in
Renton and cover a portion of the costs. Continued collaboration with the Green Cities
Partnership, WA Department of Natural Resources, community groups, and corporations would
advance the City’s planting agenda, particularly if Urban Forestry does not have the resources
to conduct all the work.
Many communities across the country partner with local non-profit organizations (NPOs) that
conduct tree planting. Based on conclusions from the needs assessment conducted as part of
the Plan, a non-profit organization devoted to the planting and stewardship of public and
private trees in Renton does not exist. The Plan provides recommendations and action steps to
pursue in an effort to establish additional partners and support from entities such as NPOs.
Public agencies, such as the U.S. Forest Service and regional air quality management districts,
may also provide grant funding, although these are typically one-time contributions rather than
a sustainable funding source. As an alternative or addition to NPOs and public agencies,
corporate partnerships may present an opportunity for financing a share of Renton’s street tree
planting and maintenance activities. Communities often establish adopt-a-tree programs and
a corresponding fund that accepts donations for street tree activities, but a formal corporate
partnership program could be a component of corporate social responsibility programs,
particularly for Renton-based businesses. In particular, large goals like increasing the City’s tree
canopy may attract corporate partners interested in environmental stewardship and a positive
public image. Emphasizing the benefits of street trees, such as clean air and water, may expand
the pool of funders to areas like public health. For example, large health or fitness corporations
may contribute substantial funds for projects and programs that promote increased access to
trails for fitness purposes. Development of a corporate partnership program would likely require
significant fundraising and outreach efforts on Urban Forestry’s part and may place the City in
competition with NPOs with highly organized fundraising programs based in Renton such as
conservancies and park foundations. Some funders may prefer to contribute to NPOs, and
therefore, it may benefit the City to partner closely with the NPO or support the establishment
of an NPO. Ideally, corporate contributions would be consistent so that the City could rely on a
sustainable funding stream.
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 91 | P a g e
Table 25. Summary of financing options for Renton’s urban forest
Financing
Options Attributes Process Opportunities Challenges
Feasible Options
Tree Fund Routine
Vegetation
Management
Permit fees
($100), building
permit fees
received, tree
mitigation fees,
and stormwater
fees could all
contribute to a
general tree
maintenance
operating fund.
Enforcement of the
Code generates
monies from
restitution.
Building permit
and stormwater
fees would need
evaluated and
adjusted to
accommodate
supporting a Tree
Fund.
Monitoring Code
violations would
generate revenue
for the Tree Fund.
Potential use of
funds for tree
maintenance.
The City is
growing and
revenue from
fees could
benefit the Tree
Fund.
Forestry staffing
levels are
inadequate to
monitor Code
violations. Fees
would need
evaluated,
adjusted, and
approved. Funds
used for tree
maintenance do
not directly affect
all contributors to
the fee programs.
Stormwater
Utility
A fee to
manage
stormwater
based on
impervious
area.
A fee from all
developed parcels
to support the
stormwater
program.
Trees reduce
stormwater
volumes. Planting
trees could
qualify property
owners a credit.
An extensive
analysis for the
appropriate utility
fee structure is
required.
Special
Assessment
Districts
Special
assessment for
landscaping,
open space
improvements,
acquisition, and
maintenance.
City agency /
property owners
initiate via petition,
City agency
administers; based
on benefits
calculated in
engineer’s report;
>50% of property
owners in
proposed district
must approve via
(mail) ballot.
Citywide district
possible for all
street trees;
individual
districts more
feasible in areas
with many trees,
high
maintenance
needs, and/or
political support.
Typically funds
more than just
street trees.
Parcel Tax Assessment
levied
independent of
property value,
can be equal
amount per
parcel or
dependent on
lot size.
2/3 of voters (not
just property
owners) must
approve via
election ballot.
Tax can be
directly related to
program costs;
maintenance
taxes deductible
for property
owners.
2/3 voter approval;
potential
competition from
other services
(e.g., schools); flat
tax distributes
cost inequitably.
General
Obligation
(GO) Bond
Low-interest
loan for capital
projects; repaid
by levying tax
revenue.
2/3 voter approval
required.
Frequently used
tool in municipal
government.
Funding provided
for set period;
maintenance
ineligible for
funding.
Program Needs 92 | P a g e
Additional Options
Parking
Benefit
District
(PBD)
Revenue from
parking meters
for range of
right-of-way
improvements.
Enacted via local
ordinance specifying
boundaries, rates,
use of funds; City
administers with
committee input.
No ballot
approval
required; visitors
bear burden over
residents.
Typically funds
more than trees.
General
Fund
City’s primary
funding pool
for wide range
of municipal
services.
Annual budget via
City’s legislative
process.
History of
funding for tree
planting and
establishment.
Not a guaranteed
source of funding;
no guaranteed
funding amount;
funds at risk if
budget shortfalls.
Partnerships Non-profits,
corporate
partners, grant
funding; for tree
planting and
establishment.
Various, depends
on City’s
processes.
Decrease costs,
increase capacity,
develop a tree
steward
organization and
program.
Union resistance,
sustainable
funding stream
required.
Carbon
Offsets
The WA Climate
Commitment Act
(May 2021)
creates a “cap
and invest”
program with a
statewide cap on
greenhouse gas
emissions and
auctions or
allocates
emissions
allowances which
supports climate
resiliency
programs.
The WA
Department of
Ecology is
developing the
program and
regulations.
House Bill 1216
(HB1216)
promotes urban
forestry programs
that will be
facilitated
through the WA
Department of
Natural
Resources.
WA is only the
second state to
pass an economy-
wide carbon cap
program, after CA.
In CA, projects
must plant at least
1,000 trees as
offset projects to
enable the sale of
carbon credits. WA
may adopt similar
requirements. Also,
HB1216 presents
opportunities.
Many trees
(5,000+) must be
planted to cover
costs of an offset
program. Creates
two types of
street trees,
offset program
trees require
higher oversight.
Does not support
tree
maintenance.
Pest Control
Fee
A fee for forestry
related services
such as pest
control and
replanting.
A forestry fee
specific to pest
control added to
the public service
utility billing as a
levy.
Opportunity to
offset costs of
managing and
recovering from
tree pests and
diseases.
Increased fee
may require
voter approval.
The City must
analyze pest
control costs to
establish the
appropriate fee
amount.
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 93 | P a g e
COMMUNITY ENGAGEMENT
The urban forest is a resource that benefits and belongs to the City’s residents. In order to care
for it, the passion that is so frequently used to talk about trees can be harnessed to build
stewardship around Renton’s trees. Approximately 71% of Renton’s tree canopy is located on
either residential (32%), commercial (22%), or industrial (17%) land (see the Urban Tree Canopy
Cover section). Thus, success in improving or maintaining tree canopy must include not only the
municipal government, but also a populace that understands the value of trees and tree canopy
to the community and the environment and how to plant and care for trees.
Engagement to Inform the Plan
Throughout the development of the Urban
Forest Management Plan, engagement
opportunities and activities were held to
gather feedback and input that would inform
the vision, goals, and strategies. The
engagement sessions launched with a project
website (RentonForestryPlan.com) where
information about the Plan and supporting
studies was provided along with upcoming
engagement events and other project
information.
During the development of the Plan, the
residents of Renton were invited to share their
“Rooted in Renton Tree Story” using an
interactive mapping feature on the project
website to map the location of their favorite
park, favorite tree, tree story, potential planting
site, and/or tree issue. A total of 10 stories were
mapped and eight photos shared. The favorite
trees included sugar maples for their fall color,
a Akebono cherry, the City’s largest London
planetree, a higan cherry, and a 67-inch tulip
tree in Tonkin Park. Tree stories captured the
benefits of cottonwoods providing food and
habitat for birds and wildlife, the history of
Nishiwaki’s gift of the Taiwan cryptomeria in
Liberty Park, a success story resulting from tree
regulations with the replacement of a horse
chestnut tree that was removed in error by a
contractor of which the City was reimbursed,
and the Yoshino cherry planted in memorial.
In addition to the interactive map, two online
surveys were hosted on the project website in
July and September 2021. The first survey gathered 123 responses and focused on identifying
viewpoints and perceptions relating to the urban forest cover, health, benefits, and programs.
The second survey’s primary objectives were to gather input on developing the Plan’s goals,
strategies, and future programs. A total of 64 responses were received.
Figure 38. Renton's Urban Forest Management Plan
project website (RentonForestryPlan.com)
Program Needs 94 | P a g e
Public Survey #1
There were 123 responses to the first survey and respondents
primarily live in Renton (55%) and own a home (82%) or live and
work in the City (17%) and reside in the Highlands (22%), City
Center (17%), or Benson (13%) neighborhoods. Respondents were
primarily white/Caucasian (76%) in the 35-44 (27%) or 55-64
(23%) age class and trees are present in their normal routine such
as daily commutes, park visits, and street trees.
The majority of respondents have planted, maintained, watered,
and pruned trees and feel there should be drastically more
canopy coverage (41%) or slightly more (38%) because they feel
the number of trees has decreased in the past 10 years (59%) as
well as the overall health (38%). The primary concern for tree-
related issues is the sidewalk and pavement cracking due to
roots. New plantings should be focused in all areas of the City
such as right-of-way, parks, private property, commercial,
schools, and subdivisions. Respondents feel that the greatest
benefit of trees is their ability to improve air and water quality
and quality of life, along with the aesthetic value and benefits to
wildlife.
Public Survey #2
The second survey received 64 responses primarily from City
Center (19%), Benson (18%), or Highlands (17%), and respondents
were in the 35-44 year old age class (30%) or the 65 and older
age class (28%), and own a home in Renton (86%). Of the
respondents, 44% support adding more funding to the
Program’s budget than what is already in place for tree planting
and maintenance initiatives. 34% desire the additional funding
to be used in neighborhoods with low tree canopy cover and
47% support more City funding for an improved proactive
pruning program for all street trees.
To further gauge the public’s opinion on priorities, each
respondent had a theoretical $100 to spend on five potential
services: tree removals and replacements; planting in public
parks; street tree plantings; Tree Preservation Ordinance
enforcement; and removal and replacement of trees that are
dead, dying, or undesirable species. The majority of respondents
would allocate $5 to $24 towards each of the five services except
for street tree planting where the majority would allocate $25 to
$49 of their $100.
75% of respondents view planting more trees in public areas as
a priority and 69% would like to see additional trees be set aside
in tree preservation tracts, retained, or replanted after
developing forested land. The primary opportunities for the City
to address in relation to citizen priorities is public tree planting
to increase tree canopy (31%), maintenance (31%), planting in
underrepresented neighborhoods (30%), and addressing
sidewalk cracking due to roots (30%).
Figure 39. Infographic
summarizing the first public
survey
Figure 40. Infographic summarizing
the second public survey
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Engagement to Implement the Plan
There are multiple ways to engage the public to improve the care of and expanse of local tree
canopy. First, topics or messages must be defined, prioritized, and limited in number. More
effective communication occurs through choosing a few strong messages and repeating them
over and over. After messages are chosen, avenues of targeted communication to deliver those
messages can be determined and implemented. Important topics and messages that should
be considered for Renton are as follows:
❖ Current Canopy Extent and Value of Renton’s Trees. The message should present the
current canopy level and benefits the canopy provides. This is typically the first message
to send out to the public, as all other messages should connect back to this one. This can
also be a way to “roll out” the Urban Forest Management Plan to the public. Include
information such as why Renton needs tree canopy, what the current canopy level is, and
the plans to improve the management of the trees that comprise the canopy. Educating
local business owners on the impact that a shady commercial district can have on sales
and educating property owners about the impact that trees have on property values are
other useful methods for boosting the desire for increased canopy along main
thoroughfares and neighborhood streets while also engaging the public. The important
value of mature trees could be also highlighted, as people often do not realize that the
large tree they have is a value to their property, the community, wildlife, and the
environment.
❖ How You Can Get Involved. What are the next steps you want people to take? The City
should decide the answer and insert this “ask” in every outreach piece or effort. The City
could organize a tree giveaway (usually saplings) at Arbor Day for people to plant on
private property. Or the City could create an Adopt-A-Tree program, whereby residents
sign up to take care of a street tree, including providing regular water and mulch. Another
option for getting the community involved is to create a Heritage Tree Program where
residents are encouraged to find and nominate the largest or otherwise significant trees
in the City. Lastly, citizens can donate funds or volunteer at a tree planting event.
❖ Tree Threats. Public and private trees can die, decline, or become safety risks as a result
of insect and disease infestation as well as inadequate maintenance. With education, the
residents of Renton can become aware of the common threats to the tree canopy and
what they can do to help. The City should provide education on existing tree pest and
disease concerns and what the City is doing about these threats on public land, and
options for management on their own land. Since the majority of the trees that comprise
the City’s urban tree canopy are on private property, it is vital for the City to educate the
public on how to detect insect and disease threats, provide information about
management and treatment options, and relay the importance of reforestation in the
event trees are removed. Informing residents about tree removals and other significant
tree work is essential for maintaining the City’s relationship with the commun ity. When
an established public tree has to be removed, the City should continue its current
practice of notifying abutting or adjacent property owners of the pending removal.
❖ General Tree Care Education for Property Owners. There are several actions people take
that are detrimental to trees at all stages of life, including improper mulching and
pruning. Easy tips and tidbits of information to share with residents for trees on their own
properties can help improve tree maintenance and increase tree health and survival
rates. Some examples include:
Program Needs 96 | P a g e
o Demonstrate how to properly mulch a tree. Too often mulch is placed around tree
trunks in a “mulch volcano”, which is extremely detrimental to the tree. A simple
message of how to mulch properly can improve tree health and longevity.
o Provide guidance on how and when to prune trees. Incorrect pruning can lead to
poor tree structure or wounds that may never heal.
o Explain proper tree planting and tree care techniques. This could be e specially
helpful for homeowners who are considering planting a tree in their yard but are
unsure where to start.
o Encourage recycling or composting leaves on-site.
Use Multiple Avenues of Communication
There are numerous avenues to convey urban forestry messages and accomplishments of the
program to the residents, such as:
❖ Social Media. Social media sites such as Facebook, Instagram, and Twitter can create
buzz and promote involvement in the current urban forestry activities occurring locally.
To reach even more people, the City should consider coordinating with allied community
gardens, non-profits, educational institutions, and business to get messages posted on
their social media sites as well.
❖ Website. The City of Renton’s Urban Forestry webpage contains important information
about the urban forestry program, including details about tree planting, the tree
inventory, tree regulations, among other things. The website should be maintained
regularly to make sure information is up to date. The project website for the Urban Forest
Management Plan (RentonForestryPlan.com) can also be maintained going forward to
continue outreach and education.
❖ Presentations to City leadership and local business and neighborhood groups. Identify
key audiences, partners, and potential champions for the urban forestry program.
Making short presentations at regular or special meetings where they are relieves
individuals from having to go to yet another meeting in the evenings. Initial outreach
could be based on letting the audience know about Renton’s urban forest and the work
called for in this Plan. Be sure to have an “ask” at the end of the presentation. What do
you want them to do next? This work often unearths new partners and funding sources
that can otherwise go untapped.
❖ Do a survey. Once a year, create a short online survey to identify what urban forestry
issues people in Renton are concerned or care about. The survey can also be used to
gauge people’s reactions to new urban forest management procedures and regulations,
and their willingness to participate in volunteer work or to donate funds or other
resources. Questions about public trees and tree canopy can be part of the annual public
survey.
❖ Cultivate partnerships for communication. Partnerships can be initiated with
organizations that can help promote, enhance, and preserve Renton’s urban forest.
Organizations can include local businesses, local utilities, regional non -profits,
homeowner associations, neighborhood associations, and schools and other educational
institutions. Other audiences to engage can include youth groups, landscape architect
firms, faith-based groups, and nurseries and landscape contractors. Actions that can be
taken by each partner should be defined before approaching them for support.
❖ Encourage Renton Technical College to become a Tree Campus USA. The College is not
yet a Tree Campus, USA. If they were to pursue this distinction and join the City’s Tree
City, USA legacy, then two powerful entities would be supporting Renton’s urban forest.
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One standard the College would need to achieve annually is for students to participate
in one or more Service Learning Projects. These projects are intended to provide an
opportunity to engage the student population with trees. College students could help
the City’s Urban Forestry Program perform many tasks, such as tree planting, tree care,
and public outreach.
❖ Publish and promote an annual State of the Urban Forest Report. An annual “State of
the Urban Forest Report” can be produced using updated tree inventory data, tree
planting statistics, i-Tree tools, and other program information. It should provide
information on the number and condition of public trees, as well as maintenance,
planting, and management accomplishments. It should also present a summary of the
current year’s annual work plan and identify emerging issues and budget or resource
needs.
❖ Add signage to the landscape. Signs placed in high traffic areas can spark interest in
trees and the urban forest. Something as simple as species name or a notable fact about
a tree can encourage people to learn more and to get more involved.
❖ Create Story Maps. The story about Renton’s urban forest, the programs that manage it,
and the community that shapes and benefits from it can be told through maps that
illuminate and contextualize the story. Maps are the visual representation of where
events happen. As such, maps and stories complement each other, and story maps serve
as an integrated presentation. Story maps use geography as a means of organizing and
presenting information. They tell the story of a place, event, issue, trend, or pattern in a
geographic context. They combine interactive maps with other rich content—text,
photos, illustrations, video, and audio—within intuitive user experiences. Content may
include the Urban Tree Canopy Assessment, the tree inventory and 2021 analysis
summary report, programs and events, and content from the Urban Forest Management
Plan such as tree canopy goals, ecosystem benefits, and the urban forest vision, goals,
objectives, and strategies.
Figure 41. Story maps can visualize urban forest stories, maps, and data for the public
Program Needs 98 | P a g e
Create a Volunteer Corps
Consider implementing a “Young Tree Care” volunteer program to assist with new tree planting
and new tree care such as watering, mulching, and pruning. This type of program is more
involved than an “Adopt-A-Tree” program, as the young tree care volunteers are specially trained
to care for young trees and to serve as advocates and educators within their networks. As such,
this type of program involves initial and continuing training, frequent mentoring, and overall
coordination of the process and volunteers. It also provides yet another engagement
opportunity and encourages partnership opportunities with a variety of groups, such as
neighborhood associations, master gardeners, scout troops, church affiliated groups, youth
groups, high school community service programs, and others to accomplish new and young
tree care tasks.
Trees to include in a “Young Tree Care” program are generally less than 6 inches in diameter.
These younger trees sometimes have branch structures that can lead to potential problems as
the tree ages, such as codominant leaders, multiple limbs attaching at the same point on the
trunk or crossing/interfering limbs. If these problems are not corrected, they may worsen as the
tree grows, which increases risk and creates potential liability. With direction from City staff,
young tree care volunteers could be trained to carry out the young tree training program.
Beyond pruning, young trees need watering and mulching to become established, and may
require fertilization and other Plant Health Care (PHC) treatments until they reach maturity. This
program can create “tree stewards” for Renton and be modeled after similar and successful
programs like those found in other municipalities such as the Tacoma Tree Foundation’s Tree
Stewards or in other states such as Portland’s Neighborhood Tree Stewards.
The “tree stewards” or a volunteer corps could also be used to support the urban forest
management program in other ways. Volunteers could develop and/or staff Arbor Day and
Earth Day events, post and manage tree messages on social media, help update the inventory,
and/or locate planting sites in neighborhoods.
Explore Partnerships
Establish partnerships to fund and accomplish the young tree training program and some
mature tree care activities. For instance, the utility companies may support tree growth
regulator applications for trees under their lines; businesses or developers may pay into a fund
to “adopt” or maintain trees in parks, commercial areas, and newly built streets; residents may
help water mature street trees during times of drought.
The City should continue to maintain and strengthen partnerships with agencies and
organizations that provide technical service and grant opportunities. For example, the WA
Department of Natural Resources Urban and Community Forestry Program provides
Community Forestry Assistance Grants, King County has set an ambitious goal of planting three
million trees by 2025 to mitigate climate change, and Washington State University Extension
Forestry in the Puget Sound Region offers technical support. These partners among many other
local, regional, and national partners can support Renton in implementing the Urban Forest
Management Plan.
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Public Education
Public education is one of the true keys to reaching the goals of an urban forestry program. Only
by educating the public, City officials, developers, and contractors working within City limits will
a community be able to achieve urban forest protection and planting goals. Ordinances and
guidelines alone will not guarantee success since builders, contractors, and others often have
their own priorities and agendas, and trees and ordinances are often nothing more than a
nuisance to them.
Cooperation from all concerned parties can be improved by requesting various community
stakeholders, such as City Council members and neighborhood groups, to attend educational
sessions to learn about the current state of Renton’s urban forest, plans for urban forest
management and planting, and the importance of all of it to the future of the community.
To gain support for Renton’s Urban Forestry Program, various public outreach campaigns aimed
at educating the residents of Renton should be established. Where there is understanding and
acceptance of the Urban Forestry Program as a whole, there will be increased support for the
planting portion of the program. Based on examples of public relations efforts by urban
foresters in other communities, the following types of activities are suggested for the City to
undertake:
❖ Hold a seminar or public meeting to discuss the tree inventory project, its results, and its
importance for the City.
❖ Develop monthly evening or weekend seminars related to tree care and landscaping;
bring in guest experts from various disciplines in the green industry.
❖ Write a monthly “Tree Talk” article for local newspapers or social media.
❖ Develop a Tree Care door hanger brochure to go to each residence where new trees are
planted; educating residents about proper tree care could help eliminate trunk damage
and improper mulching and pruning of new trees.
❖ The City could start giving away one-gallon tree seedlings to any volunteers who get
involved with City projects. This is a great reward and a way to spread the word about
trees. Renton could capitalize on the idea and attach the same Tree Care door hanger
brochure or a different informational brochure to each of these trees.
Program Needs 100 | P a g e
❖ Co-host tree planting programs with the local garden club, local non-profits, or groups.
❖ Map the locations of fruit-bearing trees in the City and coordinate with groups that
harvest the fruit for homeless and food insecure organizations.
❖ Embrace story telling within the urban treescape. Connect the trees to the history of the
area through complementary art, placards, or signage. Consider establishing tree walks
that highlight some of Renton’s greatest tree specimens and provides tree identification
training.
❖ Encourage citizen science activities that involve the urban forest. For example, the Nature
Conservancy’s “Healthy Trees Healthy Cities” app can be used to monitor tree health and
check trees for pests. Local professors and non-profit groups that work with citizen
science may be able to help plan projects and recruit citizen scientists.
❖ Expand the annual Arbor Day celebration to help it become a community tradition. The
Arbor Day celebration could be further developed as an all-day Saturday event,
preferably held in a popular park/public space setting in the City. Expanding on short
programs on planting and pruning trees and including children’s programs about trees
can help increase public interest in the City’s tree programs. Additionally, the City could
invite contractors to conduct demonstrations on tree planting, trimming, landscaping,
and species selection. Organizers could also set up booths with tree information. Refer
to the National Arbor Day Foundation (ArborDay.org) for publications that provide great
Arbor Day ideas to assist in planning of this event.
Establish a Tree Committee
Forming a Community Tree Advisory Committee (TAC)— also referred to as a tree commission,
tree board, urban forestry commission, beautification committee, environmental advisory
committee, community forestry commission, among others depending on the jurisdiction — is
one step Renton can take to sustain an urban forestry program and increase community
engagement. The powers and responsibilities of a Tree Advisory Committee are based on
Washington statutes and are assumed by the local government. By forming and empowering
a tree committee, Renton can place the responsibility for important community decisions in
the hands of unpaid volunteers with designated powers. The formation of the committee can
be a crucial element in developing broad-based support for community trees and ensuring
long-term success and growth of Renton’s Urban Forestry Program.
Proposed Responsibilities of the Tree Advisory Committee
The Tree Advisory Committee should reflect the values and standards of the community and
should help champion an urban forestry effort. The recommended roles and responsibilities of
Renton’s Tree Committee may include the following:
❖ Reduce involvement of a municipal council for tree-related matters.
❖ Administer tree removal appeals processes.
❖ Advise community leaders and staff on administering the urban forest.
❖ Stimulate and organize tree planting and maintenance.
❖ Participate in a Landmark Trees Program.
❖ Support urban forest inventories, management plans, and ordinances.
❖ Settle community disputes caused by tree removal, planting, or maintenance.
Additional guidance and information for considering a Tree Advisory Committee is provided in
Appendix C.
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 101 | P a g e
Environmental Justice
The equitable distribution of resources is a key driver of environmental justice. This Urban Forest
Management Plan aims to grow the urban forest and address the fact that existing canopy
resources and associated benefits are unequally distributed. Urban tree canopy expansion and
maintenance requires a financial investment on the part of the City, primarily from tax dollars.
As a result, tree canopy coverage tends to be larger and more established in wealthier
neighborhoods, and tree canopies are often less than ideal in communities that are
economically disadvantaged. Along with funding, community support for the urban forest and
this Plan are necessary to succeed. Communication should begin months before a tree planting
starts and should build trust between the entity spearheading the tree plantings and the
community the tree planting is taking place in. Connecting with trusted community leaders to
introduce the idea of an expanded tree canopy, holding outreach events at an earlier stage in
the plan, and taking local opinion into account when it comes to tree species selection can
develop a partnership, rooted in trust, with the area’s residents. But a big part of keeping that
trust is staying consistent through action. Following up with these communities to hear and
address any concerns while consistently maintaining the new plantings will help ensure a fully
developed urban forest. The framework of the Urban Forest Management Plan guarantees the
presence of environmental justice principles in Renton’s Urban Forestry Program.
The Tree Planting Initiative and Citywide tree canopy cover goals to be finalized by the City will
address community equity and environmental justice by identifying areas in most need of tree
canopy cover, tree plantings, and urban forestry services. And, as the City expands its network
of partners, all populations within a neighborhood will be better represented.
Support the City’s Volunteer Coordinator
To streamline community education and engagement across the City’s programs and projects
that influence the natural environment (i.e., Urban Forestry, stormwater, recycling, among
others) and to achieve goals of the Urban Forest Management Plan, the Parks and Recreation
Department’s volunteer coordinator (“Recreation Program Coordinator”) should be supported
with partnerships, organizations, the potential Tree Advisory Committee, and adjunct staff
support. The management of volunteers, events, messaging, partnerships, and programs will
build support for the Urban Forestry Program through volunteers and ensure all demographics
and cultures have an equal opportunity to experience and discuss the City’s urban forest.
Community Engagement Recommendations
Outreach and engagement with the community of Renton begins with clear messaging and
information gathered from the Urban Forest Management Plan. To make a greater impact and
to fully recognize all communities in Renton, it is recommended the City identify a local non -
profit community organization with a mission that supports the urban forest. In addition to a
community partner, a City Tree Committee adds capacity and creates more advocates for the
Urban Forestry Program. Lastly, a community of tree stewards that are trained in tree planting
and post-planting care will increase Urban Forestry Program capacity and build support for
long-lasting impacts.
Program Needs 102 | P a g e
GOALS AND
STRATEGIES FOR
A SUSTAINABLE
URBAN FOREST
Urban Forestry Goals, Objectives, and Strategies 103 | P a g e
URBAN FORESTRY GOALS, OBJECTIVES, AND STRATEGIES
Trees are an integral part of the community and the ecological systems in which they exist. They
provide significant economic, social, and ecological benefits, such as carbon sequestration,
reduction of urban heat islands, energy savings, reduction of stormwater runoff , improvement
of water quality, enhancement of human health and wellness, and increase the value of
properties. Planting and maintaining trees help Renton become more sustainable and reduce
the negative impacts on the ecosystem from urban development. Trees are as necessary as
water, infrastructure, and energy to sustaining healthy communities. The health of the urban
forest is directly linked to the health of the community.
Through research, staff interviews, data analyses, benchmarking research, community
engagement, and urban forest auditing, the City identified three specific goals with each having
several objectives to accomplish each goal. The objectives were further divided into strategies.
The Current State of Renton’s Urban Forest and Renton’s Urban Forestry Program sections
provide the context, discussions, and recommendations that led to the development of the
goal-objective-strategy framework.
The Implementation Schedule in Appendix A breaks down the strategies into actions and tasks
which are proposed to occur over a ten-year period. Through this process, the Urban Forest
Management Plan can be followed each year to culminate into the vision for Renton’s urban
forest.
Urban Forestry Goals, Objectives, and Strategies 104 | P a g e
GOALS, OBJECTIVES, AND STRATEGIES
GOAL 1: Proactively manage public trees, continue to
grow and expand a healthy canopy, maintain public
safety, and optimize urban forest benefits.
Objectives
1.1 Make data-driven management decisions.
Strategies
1.1A Maintain the public tree inventory
1.1B Utilize current and future canopy assessments
1.2 Sustainably manage the public tree population .
Strategies
1.2A Establish an interdepartmental green team
1.2B Establish and implement a 7-year pruning
cycle program
1.2C Improve workflows for tree clearance issues
1.2D Ensure newly planted trees receive post-
planting care and young tree training
1.3 Establish a strategy for increasing tree canopy
cover through City and public efforts.
Strategies
1.3A Formally establish the Tree Planting Initiative
1.3B Increase Citywide tree canopy cover
1.3C Grow a sustainable and resilient urban forest
1.4 Effectively manage tree risk.
Strategies
1.4A Adopt the Risk Tree Management Plan
1.4B Institute a formal rotation for risk tree
inspections
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 105 | P a g e
GOAL 2: Achieve environmental justice through a
partnership with the City and its residents to improve
well-being, human health, local economies, and
urban forest sustainability.
Objectives
2.1 Create an urban forestry public outreach
program that addresses all communities.
Strategies
2.1A Maintain Tree City USA recognition
2.1B Maintain active communications with
diverse audiences
2.1C Provide education and training
workshops
2.1D Implement program services through
the lens of environmental justice
2.2 Increase capacity through trained citizens.
Strategies
2.2A Create a volunteer corps or tree
stewards program
2.2B Establish a Community Tree Advisory
Committee
2.2C Effectively manage volunteers and
events
Urban Forestry Goals, Objectives, and Strategies 106 | P a g e
GOAL 3: Strengthen policies for preserving the
environmental benefits, management, and the
character of Renton's urban forest.
Objectives
3.1 Strengthen policies for protecting the urban forest.
Strategies
3.1A Protect trees during public construction projects
3.1B Apply a no-net-loss approach to tree canopy
cover
3.1C Use tree canopy assessment data for tree
management policies
3.1D Update and strengthen tree ordinances
3.2 Improve workflows and operations for sustainable
urban forest management.
Strategies
3.2A Enforce tree regulations
3.2B Engage more consistently in all tree removal
permit requests
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 107 | P a g e
KEY STRATEGIES
The planning process identified 22 strategies following development of the program goals and
objectives. This rich number of strategies will position Renton as a leader in urban forestry across
the state and perhaps the nation and will guide the City towards a sustainable urban forest.
There were five significant strategies identified as being of higher priority than others. These
were predicated upon resolving public safety issues, inefficiencies, community engagement,
policy gaps, and urban forest sustainability.
7-Year Pruning Cycle Program
One of the more critical strategies identified was the need
for an improved public tree pruning program on a
recommended 7-year rotation. The strategy requires
additional funding and the creation of an in-house arborist
crew. Feedback from the community and City staff
expressed support for the structure of this strategy.
Tree Planting Initiative
To grow an urban forest that is sustainable and resilient to climate change, pests and diseases,
and urban development pressures, a strategic planting initiative guided by short- and long-term
canopy goals and planting targets is needed. The Plan contains the guidance for finalizing
canopy goals, identifying priority planting areas, and developing the tree planting initiative.
Tree Stewards Program
A shared commitment to the urban forest and vision is essential to the long-term success and
impact of the Plan. A community of tree stewards will increase Urban Forestry Program capacity
and support the Tree Planting Initiative along with other programs and services.
No-Net-Loss
Perhaps more important than tree canopy cover goals and planting initiatives is the foundation
of sound policies to preserve the existing urban forest. With this key strategy, tree replacement,
retention, removal, mitigation, and enforcement protocols are solidified. In addition, alternative
solutions to tree and sidewalk conflicts are explored and guidance for formally adopting a
decision checklist and solutions toolkit is provided.
Enforce Tree Regulations
Throughout the planning effort, concerns were expressed and identified relating to the
protection of trees from construction damage, illegal removals, and maintenance malpractice.
The actions supporting this strategy expand the enforcement efforts by increasing capacity as
well as community education to prevent instances from occurring in the first place.
Key Strategies
7-year pruning cycle program
The Tree Planting Initiative
Tree Stewards Program
No-net-loss
Enforce tree regulations
Evaluation 108 | P a g e
EVALUATION
MONITORING PLAN
This Urban Forest Management Plan will be updated and revised periodically to reflect changes
in the urban forest resource structure and function, to incorporate changes in industry
standards, to consider community response, and to measure the progress of the urban forest
partners in implementing the recommendations and reaching the established goals. This
process should be implemented by the City Collaborative Team (or similar) using the Evaluate,
Monitor, Report, and Revise methodology.
Knowing how the City of Renton and its partners are doing will require a continual process of
evaluation. This section presents examples of how to monitor, analyze, and revise the Plan,
which will keep stakeholders informed of the status of the Urban Forest Program. To monitor
progress toward implementing the Plan recommendations, an evaluation similar to the U.S.
Forest Service’s Urban Forest Audit conducted to develop the initial Plan should be completed.
This evaluation will identify progress and shortfalls compared to the baseline audit.
In addition, a report card could be created based on outcomes of the audit and distributed to
the public every two to three years. This will measure the progress toward implementing the
Plan actions. The following example provides a suggested reporting structure to measure
success toward accomplishing each goal. Other indicators to measure progress may need to be
developed to ensure a thorough and accurate evaluation.
Evaluate
The U.S. Forest Service’s Urban Forest Audit System provides a framework for routine
evaluations of the urban forest, the programs that manage it, and the community that shapes
and benefits from it. The deliverables to this Urban Forest Management Plan project include
guidance for completing the audit. It is recommended the City Collaborative Team (or similar)
complete a bi-annual audit to inform any alterations to actions and strategies.
This audit system consists of 11 categories of urban forest management, sustainability, and
community. Within the 11 categories are approximately 130 elements. Each element was ranked
or scored based on the consultants’ evaluations in 2022 for the Urban Forest Management Plan.
The City Collaborative Team (or similar) should complete an update to this ranking bi-annually
to inform Plan reporting, monitoring, and revision as described in the following sections.
Monitor
Measuring accomplishment of the actions will require ongoing analysis. The outcomes of the
Urban Forest Audit System in the “Evaluate” section can be used to monitor change over time.
These benchmark values should be tracked, and a state of the urban forest report should be
prepared and distributed to the public every 2 to 5 years. Analysis may include an updated
public tree inventory, i-Tree benefits analyses, or urban tree canopy assessments. The state of
the urban forest report should include the benchmark values as reported in the Plan and the
Urban Forest Audit System as of 2021, so that the City can measure and compare changes to
the urban forest. The report should reflect changes to the audit system that are measured.
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 109 | P a g e
Renton’s Urban Forest Benchmark Values
Table 26. Renton’s urban forest benchmark values
URBAN TREE CANOPY (UTC) COVER (2017)
UTC 29.3%
Recommended Canopy Goal (short-term) 30% by 2032
Recommended Canopy Goal (long-term) 33% by 2042
Total Number of Trees to Plant (short-term) 5,250 (525 trees per year)
Total Number of Trees to Plant (long-term) 19,000 (950 trees per year)
City-led Plantings to Reach Canopy Goals
(60% of total plantings)
315 trees/year for 30% canopy
570 trees/year for 33% canopy
PUBLIC TREE COUNTS (2021)
Total Public Trees Managed 116,984
Public Street/Park/Golf Course Trees (inventoried) 27,456
Public Natural Area Trees (sampled) 89,528
TREE SPECIES DIVERSITY (SPECIES EXCEEDING 10%)
Public Trees (2021) Bigleaf maple (15%), Douglas-fir (11%)
TREE BENEFITS
Citywide (UTC Assessment) 2017: $2.4 million (annual)
Inventoried Public Trees 2021: $220,000 (annual)
Inventoried Public Trees Replacement Value 2021: $122.6 million
TREE AND BUDGET DISTRIBUTION (2021)
Public Trees per Capita 1.15
Budget per Capita, Budget per Tree $9.37, $8.13
Urban Forestry Program FTEs 2.50
Total Public Trees per Staff 46,800
MANAGEMENT ACTIVITIES (2020)
Public Trees Pruned 758
Public Trees Removed 247
Public Trees Planted 200
Trees Watered 400/week
Trees Inspected 3,700
Completed Work Orders 1,000+
Number of Volunteers and/or Hours TBD
URBAN FOREST AUDIT SYSTEM (TOTAL SCORE OF 2021): 65%
Management Policy and Ordinances 64%
Professional Capacity and Training 81%
Funding and Accounting 58%
Decision and Management Authority 88%
Inventories 77%
Urban Forest Management Plans 46%
Risk Management 83%
Disaster Planning 43%
Standards and Best Management Practices 55%
Community 86%
Green Asset Evaluation 55%
PUBLIC PERCEPTION (2021)
Health of the urban forest in the past 10 years 38% feel the health has declined
Count of trees in the urban forest in the past 10 years 59% feel the number has declined
Amount of urban tree canopy cover 48% want drastically more canopy
Evaluation 110 | P a g e
Report
Based on the evaluation of Plan implementation progress, the City Collaborative Team (or
similar) should track, record, and report on the metrics described below that are measures or
indicators of success for each goal and supporting actions. Note, the ser ies of urban forestry
goals to address the resource, the programs, and the people and are not listed in any particular
priority or order.
Table 27. Evaluation, monitoring, and reporting techniques to achieve the urban forestry goals
1
GREEN ASSET MANAGEMENT:
Proactively manage public trees, continue to grow and expand a healthy
canopy, maintain public safety, and optimize urban forest benefits.
❖ Report the ecosystem benefits of the inventoried tree population.
❖ Report the number of public trees pruned, removed, and planted.
❖ Report the number of trees managed for pests and diseases.
❖ Report the number of trees planted in stormwater management projects.
❖ Report progress towards canopy goals and tree planting targets.
❖ Report the volume of woody biomass utilized.
❖ Report the condition, structure, and diversity of the public trees.
❖ List audit score and actions/targets achieved, ongoing, and not started.
2
COMMUNITY ENGAGEMENT:
Achieve environmental justice through a partnership with the City and its
residents to improve well-being, human health, local economies, and urban
forest sustainability.
❖ List the existing and potential outreach platforms and initiatives.
❖ List existing and potential partners.
❖ Report the number of planting events and trees planted.
❖ Report the history/count of Tree City USA and supporting awards.
❖ Report the number of volunteers, events, and volunteer hours.
❖ Report the number of private tree plantings as feasible.
❖ Report the number of trainings, workshops, and attendees.
❖ Report the results of public surveys.
❖ Recognize exemplary urban forest stewards.
❖ List audit score and actions/targets achieved, ongoing, and not started.
3
TREE MANAGEMENT POLICY:
Strengthen policies for preserving the environmental benefits, management,
and the character of Renton's urban forest.
❖ List existing and potential partners.
❖ List all City and partner-led planning efforts.
❖ Describe related planning efforts.
❖ Establish a Citywide canopy goal and local planting targets.
❖ List recommended changes to City Code, policies, and manuals.
❖ List audit score and actions/targets achieved, ongoing, and not started.
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 111 | P a g e
Revise
Completion of this Plan is a critical step towards meeting the vision for Renton’s urban forest.
Continual monitoring, analysis, and reporting will help to keep urban forest partners involved
and focused on accomplishing the actions. Plans are typically revised every 10 to 15 years; hence,
the Plan will need formal revision to respond and adapt to changes as they develop. Formal
revision of the Plan should coincide with the update of the City’s Comprehensive Plan and other
relevant planning efforts. Recommendations and goals of each should be compared. Revisions
to the Plan should occur with major events, such as newly discovered pests or diseases, changes
in program budget and resources, or significant changes to industry standards or legal codes.
ACT AND REPORT EVALUATE AND REVISE ACT AND REPORT EVALUATE AND REVISE
Years 1-5 Year 5 Years 6-10 Year 10
Annual Action
Plans and
Reports
Urban Forest Audit
and Plan
Amendments
Annual
Action Plans and
Reports
Urban Forest Audit
and Plan
Update
Monthly
Activities and
Annual Report
Updated
Benchmarks and
Plan Actions
Monthly
Activities and
Annual Report
Updated
Benchmarks and
Plan Actions
IMPLEMENTATION SCHEDULE
The Appendix contains the Implementation Schedule which is the yearly program for the next
ten years. It takes the strategies, shown under the goals and objectives, and subdivides each
strategy into actions and tasks. In addition, the Implementation Schedule shows a budget
estimate with a total by year. The Schedule is the main piece of the Plan that can be easily
adapted to changing conditions, providing more or less activity in any given year. The
Implementation Schedule will be used by City staff to guid e activities occurring in the current
year and to plan for succeeding budget years. It provides the reader with information on how
each program strategy is to be accomplished.
Figure 42. Example of the plan implementation, evaluation, and revision process
Summary and Conclusion 112 | P a g e
SUMMARY AND CONCLUSION
Renton has a rich forestry history that strongly influenced the City’s early development. Today,
with all of the original vegetation gone, the urban forest plays an important role in making life
richer for Renton citizens and visitors, and attracting new b usinesses. To resolve many of the
issues with the built and the natural environments experienced today, this Urban Forest
Management Plan is timely. With dedication, Renton’s urban forest will once again provide the
value of the historic landscape. The Urban Forest Management Plan is a roadmap for a strategic
approach to manage Renton’s urban forest. The Plan contains goals and supporting actions
that are critical to the long-term vitality of the forest. However, in order for the Urban Forest
Management Plan to actually have an impact on the forest resource, it requires stewardship
and financial resources to begin implementation. Further, it needs to be institutionalized as a
document requiring implementation with a sense of urgency to get things started. Co mpletion
of the Urban Forest Management Plan clearly demonstrates that City leadership understands
that a healthy urban forest is critical to guaranteeing the long-term health and vitality of the
community, and that it is not a luxury but an absolute necessity. In order to accomplish the
goals, the approach to overall implementation should adhere to the guiding principles of the
Plan:
❖ Recognize that the trees of the urban forest are more than aesthetic enhancements.
❖ Recognize trees as the backbone of the urban ecosystem and an essential part of the
community’s green infrastructure.
❖ Promote the health and growth of the urban forest by following scientifically established
best management practices for tree selection, planting, watering, and pruning.
❖ Promote a robust urban forest through policies and practices that reduce its vulnerability
to known diseases or pest infestations, and future threats, including the anticipated
effects of climate change.
❖ Engage in a continuous process of long-range planning for the growth and maintenance
of the urban forest.
❖ Promote public appreciation of the urban forest through educational outreach
programs.
❖ Support local businesses, institutions, organizations, and individuals in their efforts to
grow and maintain the urban forest through community education.
❖ Proceed in a manner that is inclusive and transparent.
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 113 | P a g e
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 A | P a g e
APPENDICES
APPENDIX A. IMPLEMENTATION SCHEDULE B
A 10-year annual work plan to achieve the urban forest vision and goals.
APPENDIX B. SOLUTIONS WORKBOOK AND POSSIBLE GUIDELINES FOR TREE AND SIDEWALK CONFLICTS F
A decision checklist and solutions kit for consideration in dealing with tree and
hardscape conflicts. Supports tree preservation and canopy goals along with City ADA
requirements.
APPENDIX C. GUIDANCE TO DEVELOP A TREE ADVISORY COMMITTEE Q
To increase Urban Forestry Program capacity and support, the guidance for
establishing a volunteer committee of tree advocates is provided.
APPENDIX D. 2021 URBAN FOREST AUDIT SYSTEM RESULTS T
To inform the development of the Plan’s goals, objectives, and strategies, the U.S. Forest
Service’s Urban Forest Sustainability and Management Audit System was
implemented. This evaluation or audit identifies the City’s urban forest management
strengths and opportunities and provides a framework for monitoring Plan
implementation and success.
APPENDIX E. RISK TREE MANAGEMENT PLAN EE
The draft strategy to manage tree risk and public safety is included for City
consideration and adoption.
APPENDIX F. URBAN FOREST PEST READY ASSESSMENT QQ
The State of WA developed the Urban Forest Pest Readiness Playbook and includes an
assessment worksheet to gauge and prepare communities for potential tree pest
outbreaks. Completing the assessment worksheet is a Plan action (Action #1.5A.5) and
completing it will close the gap in readiness and response capabilities.
APPENDIX E. REFERENCES VV
Provides a list of the resources, research, and studies referenced in and supporting the
Plan in the order they are provided.
Appendices B | P a g e
Strategies and Actions YR2022 YR2023 YR2024 YR2025 YR2026 YR2027 YR2028 YR2029 YR2030 YR2031
1.1 Make data-driven management decisions
1.1A Maintain the public tree inventory
Action 1.1A.1 Track all maintenance history of public trees
Action 1.1A.2 Add newly planted trees to the inventory
Action 1.1A.3 Quantify the ecosystem benefits of the public trees
Action 1.1A.4 Monitor and assess the public tree population for risk and tree pests/diseases
1.1B Utilize current and future canopy assessments
Action 1.1B.1 Plant trees based on themes such as low tree canopy cover, low tree equity, and environmental conditions
Action 1.1B.2 Update policies and design guidelines to preserve existing tree canopy cover
Action 1.1B.3 Prepare scope of work and RFP for updated canopy assessment
Action 1.1B.4 Execute contract and complete the canopy assessment $10,000 $10,000
Action 1.1B.5 Refine canopy goals and planting priorities
1.2 Sustainably manage the public tree population
1.2A Establish an interdepartmental green team
Action 1.2A.1 Identify key members
Action 1.2A.2 Finalize members, meeting intervals, team objectives
Action 1.2A.3 Meet regularly to address workflows, communications, knowledge sharing
Action 1.2A.4 Tree managing staff should engage in City department planning such as updates to the City’s
comprehensive plan
1.2B Establish and implement a 7-year pruning cycle program
Action 1.2B.1 Finalize the annual costs for a 7-year pruning cycle
Action 1.2B.2 Finalize the annual costs for the in-house arborist crew
Action 1.2B.3 Finalize the framework for the pruning program (City grids, priority areas, in-house vs. contracted)
Action 1.2B.4 Submit budget request for pruning program
Action 1.2B.5 Submit budget request for in-house arborist crew
Annual staff cost $168,000 $168,000 $168,000 $168,000 $168,000 $168,000 $168,000 $168,000 $168,000
Vehicle and equipment purchase $410,000
Annual operating costs $102,698 $102,698 $102,698 $102,698 $102,698 $102,698 $102,698 $102,698 $102,698
Annual training, certifications, and membership costs $2,000 $2,000 $2,000 $2,000 $2,000 $2,000 $2,000 $2,000 $2,000
Action 1.2B.6 Prune 3,654 public trees annually and adjust as the population grows $134,000
1.2C Improve workflows for tree clearance issues
Action 1.2C.1 Document existing workflows and procedures
Action 1.2C.2 Identify inefficiencies and resource needs
Action 1.2C.3 Increase public education on private tree right-of-way encroachment
Action 1.2C.4 Formalize standard operating procedures between departments
Action 1.2C.5 Utilize in-house arborist crew for all public tree clearance requests
1.2D Ensure newly planted trees receive post-planting care and young tree training
Action 1.2D.1 Establish maintenance plans for new plantings
Action 1.2D.2 Plant trees using the right tree, right place approach
Action 1.2D.3 Educate the public and gather local community input on public tree plantings
Action 1.2D.4 Acquire commitments from the local community and property owners to water new trees
Action 1.2D.5 Utilize the newly developed community tree steward program
APPENDIX A. IMPLEMENTATION SCHEDULE
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 C | P a g e
Strategies and Actions YR2022 YR2023 YR2024 YR2025 YR2026 YR2027 YR2028 YR2029 YR2030 YR2031
1.3 Establish a strategy for increasing tree canopy cover through City and public efforts
1.3A Formally establish the Tree Planting Initiative
Action 1.3A.1 Finalize tree canopy goals and priority planting areas and themes
Action 1.3A.2 Establish a Citywide tree planting plan and strategies $6,000
Action 1.3A.3 Identify local community partners for planting, maintenance, and funding
1.3B Increase Citywide tree canopy cover
Action 1.3B.1 Increase tree canopy cover with City-led plantings (570 trees per year, $150 per tree)$50,000 $85,500 $85,500 $85,500 $85,500 $85,500 $85,500 $85,500 $85,500 $85,500
Action 1.3B.2 Increase tree canopy cover through partnerships and property owner-led plantings (380 trees per year)
1.3C Grow a sustainable and resilient urban forest
Action 1.3C.1 Monitor and analyze the inventory for species diversity
Action 1.3C.2 Update a Recommended Tree List for City-led projects
Action 1.3C.3 Work with local nurseries to expand tree species options
Action 1.3C.4 Strengthen storm and disaster preparations, mitigations, and recovery strategies, protocols, and
mechanisms
Action 1.3C.5 Complete the WA Urban Forest Pest Readiness Playbook Assessment (UFMP Appendix F)
1.4 Effectively manage tree risk
1.4A Adopt the Risk Tree Management Plan
Action 1.4A.1 Update the draft Risk Tree Management Plan
Action 1.4A.2 Acquire approval from Risk Management
Action 1.4A.3 Implement the Risk Tree Management Plan
1.4B Institute a formal rotation for risk tree inspection
Action 1.4B.1 Maintain an inventory of public trees
Action 1.4B.2 Apply industry standards and best practices and implement the Risk Tree Management Plan
Appendices D | P a g e
Strategies and Actions YR2022 YR2023 YR2024 YR2025 YR2026 YR2027 YR2028 YR2029 YR2030 YR2031
2.1 Create an urban forestry public outreach program that addresses all communities
2.1A Maintain Tree City USA recognition
Action 2.1A.1 Maintain accurate records for the application
Action 2.1A.2 Submit annual application
Action 2.1A.3 Arbor Day Celebration and Proclamation
Action 2.1A.4 Submit application for Tree City USA Growth Award
Action 2.1A.5 Acquire 10 Growth Awards for Sterling Tree City USA status
2.1B Maintain active communications with diverse audiences
Action 2.1B.1 Develop a community outreach plan with collaboration from City departments
Action 2.1B.2 Formalize messaging for various audiences (property owners, developers, HOAs, youth, tree companies)
Action 2.1B.3 Update the City's website with UFMP information
Action 2.1B.4 At least quarterly, share information and updates
Action 2.1B.5 Gather feedback and input using public surveys to inform future messaging
2.1C Provide education and training workshops
Action 2.1C.1 Use the outreach plan (Action 2.1B.1) to finalize topics, audiences, approach
Action 2.1C.2 Identify existing resources and tools for workshops
Action 2.1C.3 Identify and collaborate with community partners
Action 2.1C.4 Support youth education of environmental topics, engage schools with Arbor Day events
Action 2.1C.4 Lead or support at least one training or education material annually $2,000 $2,000 $2,000 $2,000 $2,000 $2,000 $2,000 $2,000
2.1D Implement program services through the lens of environmental justice
Action 2.1D.1 Identify local community groups and partners to represent all neighborhoods
Action 2.1D.2 Identify low canopy neighborhoods for targeted engagement
Action 2.1D.3 Explore with partners the 3-30-300 rule for community greening
Action 2.1D.4 Develop strategies to remove barriers to participation for all community members
Barriers to address include ADA communications compliance, internet access, languages, transportation
2.2 Increase capacity through trained citizens
2.2A Create a volunteer corps or tree stewards program
Action 2.2A.1 Identify a local community partner to support urban forestry and the tree stewards program
Action 2.2A.2 Establish a training curriculum and gather available resources
View an example Tree Steward Manual here https://treesvirginia.org/images/pdfs/2020TreeStewardManualver03.pdf
Action 2.2A.3 Announce the program and set up an online or in-person training event
2.2B Establish a Community Tree Advisory Committee
Action 2.2B.1 Organize interested citizens and outline challenges and opportunities
Action 2.2B.2 Hold informal meetings with concerned citizens and local officials
Action 2.2B.3 Meet with the City Attorney to finalize the framework
Action 2.2B.4 Finalize the powers, authority, and responsibilities
Action 2.2B.5 Draft the ordinance and the staff report for adopting the ordinance
Action 2.2B.6 Seek the Council's approval of the ordinance at a public hearing
2.2C Effectively manage volunteers and events
Action 2.2C.1 Identify needs and interests from multiple departments
Action 2.2C.2 Work with the City's Volunteer Coordinator to strengthen the outreach plan (Action 2.1B.1)
Action 2.2C.3 Identify opportunities to increase capacity for the Volunteer Coordinator (e.g., seasonal, Tree Committee,
volunteers)
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 E | P a g e
Strategies and Actions YR2022 YR2023 YR2024 YR2025 YR2026 YR2027 YR2028 YR2029 YR2030 YR2031
3.1 Strengthen policies for protecting the urban forest
3.1A Protect trees during public construction projects
Action 3.1A.1 Continue to review tree and sidewalk conflicts
Action 3.1A.2 Update and standardize construction design standards (4-4-130.H.9) to include requirements of ANSI
A300 Construction Management Standard - Part 5
Action 3.1A.3 Perform construction project inspections to ensure proper tree protection requirements are implemented
and maintained
Action 3.1A.4 Establish a fee schedule for violation of Tree Protection Zones (TPZ)
Action 3.1A.5 Add definition to support role of Urban Forestry Program provided to Code Compliance
3.1B Apply a no-net-loss approach to tree canopy cover
Action 3.1B.1 Update the 1 to 1 tree replacement requirement for CIP or infrastructure projects with the same
requirements as residential parcels requiring every inch be replaced
Action 3.1B.2 Require 30% tree retention include best specimen trees, especially landmark trees, and the percentage is
calculated prior to roadway overlay
Action 3.1B.3 Amend landmark trees minimum diameter to 24 inches or greater
Action 3.1B.4 Require a permit for the removal of any trees greater than 6 inches DBH for development projects
Action 3.1B.5 Add alternative solutions for tree and sidewalk conflicts to include low impact design (LID) options for
surface water mitigation
Action 3.1B.6 Develop a fee-in-lieu of payment for the value of any trees removed from the development site and not
planted back into the landscape
Action 3.1B.7 Update the method for tree value calculation using CTLA trunk-formula method or increase the inch fee to
$250 per inch
3.1C Use tree canopy assessment data for tree management policies
Action 3.1C.1 Evaluate causes for canopy loss from the 2010 and 2017 assessments, specifically the loss on Resource
Conservation land (-2.1%)
Action 3.1C.2 Update policies to include long-term and intermediate Citywide and local canopy goals
3.1D Update and strengthen tree ordinances
Action 3.1D.1 Prepare or modify a report that proposes necessary Code updates and additions
Action 3.1D.2 Coordinate with Planning Department and others to prepare new Code docket items
Action 3.1D.3 Share with the public the adopted changes to tree-related Code
3.2 Improve workflows and operations for sustainable urban forest management
3.2A Enforce tree regulations
Action 3.2A.1 Enforce tree protection during construction, inspect Tree Protection Zones, inspect tree retentions
Action 3.2A.2 Continue to support the contracted Inspecting Arborist or utilize potential in-house arborist crew
Action 3.2A.3 Update contractor business license requirements
Require a Renton Tree Regulations competency test
Require Certificate of Insurance
Fine for no business license is increased to $1,000
Tree code violations result in loss of license
Action 3.2A.4 Consolidate tree-related policies, guidelines, best practices, and standards into a tree manual for multiple
audiences.
3.2B Engage more consistently in all tree removal permit requests
Action 3.2B.1 Evaluate the feasibility of tree removal permitting to be managed by Urban Forestry
Action 3.2B.2 Explore the costs and funding mechanisms for a full-time development review arborist
Green Asset Management Goal Costs $184,000 $774,198 $368,198 $358,198 $358,198 $358,198 $358,198 $368,198 $358,198 $358,198
Community Engagement Goal Costs $0 $0 $2,000 $2,000 $2,000 $2,000 $2,000 $2,000 $2,000 $2,000
Tree Policy Goal Costs $0 $0 $0 $0 $0 $0 $0 $0 $0 $0
Total Costs $184,000 $774,198 $370,198 $360,198 $360,198 $360,198 $360,198 $370,198 $360,198 $360,198
Appendices F | P a g e
APPENDIX B. SOLUTIONS WORKBOOK AND POSSIBLE GUIDELINES FOR TREE AND
SIDEWALK CONFLICTS
Decision Matrix
The development of Renton’s Urban Forest Management Plan identified the need to clarify the
decision process to address tree and sidewalk or construction conflicts. A clear decision matrix
can help to reduce inter- and inner-department uncertainty and establish or adhere to
consistency and fairness. The City’s departments have standard operating procedures and
checklists for evaluating conflicts at a project site, but these traditionally have not been
available to the public. To make the decision process around the retention or removal of trees
more transparent and consistent, a clarified process, decision matrix, and solution toolkit should
be developed to highlight the key decision points.
Proposed Decision Matrix for Tree and Construction/Sidewalk Conflicts
Initial Assessment
The following applies to tree removal requests and proposed projects.
The initial assessment of trees, sidewalks (or other infrastructure), and site at the service request
location or project location provides consistency and predictability by collecting the
appropriate information. It is recommended to have the Urban Forestry Program involved in
the initial assessment process and/or a City staff member with an International Society of
Arboriculture Certified Arborist accreditation.
• Tree Preservation Potential. What is the tree quality or health, and is it worth preserving?
Is the tree designated as a significant tree or Landmark Tree?
• Tree Mitigation Exploration. If the request to remove the tree is a result of infrastructure
damage and the tree exhibits poor health or vigor, can the tree’s health or vigor be
mitigated by any means other than removal?
• Public Safety Risk. Is the tree a potential hazard that cannot be mitigated by any means
other than removal? This includes any tree or tree part that poses a high risk of damage
to persons or property located in public places. Use the International Society of
Arboriculture’s tree risk evaluation standards.
• Initial Assessment Timing. It is recommended that the initial assessment be conducted
within 3-4 weeks of receiving a service request for removal. If the assessment is required PUBLIC INVOLVEMENT SERVICE REQUEST
RECEIVED
CITY PROPOSED
PROJECT
DEVELOPER
PROJECT OTHER
PROJECT IMPLEMENTATION
SOLUTIONS
FURTHER EVALUATION
INITIAL ASSESSMENT
Figure 43. Proposed
decision matrix for
tree and
construction
conflicts
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 G | P a g e
due to a proposed project, the assessment should occur no later than 30% design or
equivalent of design effort (e.g., during the Environmental Assessment period).
• Tracking. Consider tracking service requests in the City’s asset software or simil ar
program.
• For an example Initial Assessment Checklist, see the Example Initial Assessment
Checklist further below.
Initial Tree Decision
If the tree removal request was made due to the condition of the tree or other reason not
relating to the damage or impediment of infrastructure such as sidewalk, the Urban Forester or
representative may conduct the initial tree decision. If infrastructure is part of the assessment
and/or the tree removal request was initiated for a proposed project, the City Engineer or
appropriate staff should also be part of the initial tree decision. The appropriate staff will visit
the tree and/or proposed project location and assess the tree (and sidewalk, if applicable)
conditions. The following actions will result from the assessment:
• Remove Tree. The tree removal request was made not as a result of the tree impacting or
damaging infrastructure and the tree is identified as unhealthy or unsafe with no
remediation possible.
- Remove the tree and consider the “no net loss” policy of replacing the tree. Some
cities implement a 2:1 replacement to removal ratio. The replacement policy should
be based on City Code. Replacement of trees can occur on site, same street, or City -
approved location. A fee in-lieu should also be considered as an option as described
in City Code.
- Removal of the tree should be prioritized based on other work orders, the risk
assessment of the tree, and other factors.
- The service request, decision, work order, tree information, and tree removal
information should be tracked in the City’s asset software or similar program.
• Retain Tree. Based on the assessment, the tree is not in decline or the issues can be
remediated. Alternatively, if the tree in question is designated as a Landmark Tree or
significant tree, the tree may be preserved depending on the tree condition and presence
of hazards or risks as described in the City policies and manuals.
- Document the decision, inform the property owner or project developer.
- Conduct the remediation activity to the tree if needed.
- Prioritize and track this information in the asset software or similar program.
- Conduct follow-ups with the property owner and monitor the tree if necessary.
• Remove Tree and Replace Sidewalk. The service request or proposed project identifies a
tree that is causing sidewalk conflicts and the tree has been deemed unhealthy and no
remediation is possible. The City should reference City Code as to what is defined as
unhealthy or hazardous.
- Remove the tree and consider the “no net loss” policy of replacing the tree. Some
cities implement a 2:1 replacement to removal ratio. The requirement to replace the
tree will be the City and Urban Forester’s discretion. The replacement policy should
be based on City Code. Replacement of trees can occur on site, same street, or City-
approved location. A fee in-lieu should also be considered as an option as described
in City Code.
- Removal of the tree should be prioritized based on other work orders, the risk
assessment of the tree, and other factors.
Appendices H | P a g e
- The service request, decision, work order, tree information, and tree removal
information should be tracked in the City’s tree inventory software or similar program.
- Replace the sidewalk using appropriate design standards and materials and consider
designing according to standards that will protect any replacement trees and provide
ample soil volume and root space for the new or existing trees.
• Retain Tree and Maintain Sidewalk. A tree in question is in conflict with infrastructure
and the assessment determined that the tree is to be retained and the infrastructure (i.e.,
sidewalk) is to be corrected. The sidewalk will be of standard width and a tree pit of
standard width (at minimum) can be installed or retained.
- Coordinate with Public Works the timing and approach for maintaining the sidewalk.
Be sure to consider alternative sidewalk amendments such as width reduction,
alternative materials, among other solutions.
- If any root pruning is needed to amend the sidewalk, the Urban Forester and/or a
Certified Arborist hired by the City should evaluate to determine the appropriate root
pruning, branch pruning, soil amendments, and other maintenance required.
- Documentation in City’s asset software as stated before is recommended.
• Evaluate Tree and/or Sidewalk Further. During the initial tree decision, it is not
appropriate for extensive explorations of pavement, soils, or tree root systems. There are
limitations to the initial assessment and decision. The purpose of the initial assessment
is to identify where these future actions are requ ired so that the appropriate schedule
and funding can be determined.
- Documentation in City’s asset software as stated before is recommended.
Further Evaluation
The team conducting further evaluation may include an arborist, landscape architect, engineer,
or other professionals with expertise relevant to the project details and situation. In addition to
collecting information about the trees and infrastructure (i.e., sidewalk) the following additional
items may be considered:
Level of impact, future risks, cost/benefit, anticipated sidewalk maintenance if the
tree is kept, public/environmental benefit, community values, policy guidance,
neighborhood context, historic districts, planned construction, funding forecasts.
Solutions
The following best practices and approaches are provided as examples. The City should review
and update these as new or improved practices and materials emerge.
• If Tree Removed, Obtain Valuation. If the tree must be removed, the City should provide
guidelines to replace the removed tree. Guidelines should be based on City Code. Ideally,
the tree would be replaced at the same location if the site is suitable for trees in the first
place. If not possible, the City should have a procedure in place for the relocation of
replacement trees.
• If Tree is Retained, Determine Management Approach. Since the initial assessment
offered the opportunity to closely examine the tree and the site, future management
approaches and decisions should be discussed and documented. These include future
tree replacement species for when the tree does over mature and decline or conduct
corrective actions to provide clearance for pedestrians, vehicles, utilities, and signs.
• Identify Potential Sidewalk Solutions. The Alternative Solutions Toolkit Overview section
provides information and resources regarding sidewalk solution options. Information
gathered during the initial assessment and subsequent site visits will support the
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 I | P a g e
selection of options that should be presented to City staff to ensure goals of sidewalk
repair and tree preservation are kept.
• Identify Opportunities to Improve Conditions for New Trees. When trees are planted by
the City, the appropriate tree species for the location should be determined and the City
should adhere to best practices in site and tree pit preparation to provide enough soil
volume to support tree root growth and minimize future pavement damage by roots. If
a tree is being planted at or near where the tree removal request was made, an evaluation
of why the request was made should be considered. This may include such things as
inadequate soil volume, insufficient growing space, tree leaf litter, messy fruit, poor
structure, allergies, screening of shade-intolerant garden or landscape vegetation, or a
combination of factors.
Project Implementation
Whether the sidewalk repair is occurring at a location where the tree is retained or removed,
the sidewalk must adhere to the Americans with Disabilities Act (ADA) requirements and City
standards and is the responsibility of the City. Tree repaving projects, curb and gutter repairs,
and other Capital Projects should also adhere to this evaluation process. All matters relating to
the removal or remediation of the tree will be conducted by the City unless the responsibility of
tree maintenance in public rights-of-way changes. Regarding tree maintenance, mitigation, or
removal, the City should involve the public by:
• Providing a public notice prior to the initial tree assessment.
• Share the results of the initial assessment.
• Share the solution decision.
Appendices J | P a g e
EXAMPLE INITIAL ASSESSMENT CHECKLIST
[CITY LOGO]
[City of ####] Trees and Sidewalks Operations Plan
Initial Street Tree and Sidewalk Assessment Checklist
DATE
Prepared By:
The purpose of this document is to outline INITIAL ASSESSMENT for locations where sidewalk work is located
within the dripline of an existing street tree.
Project Location/Address
Tree Species/Diameter
Street Classification/Type
Tree Asset Inventory ID
Sidewalk Segment #
Is this assessment along a
corridor project?
An [ENGINEER] and [ARBORIST] will look at the site and assess the condition of the sidewalk and the tree.
If the tree has the following characteristics, it should be removed/replaced pursuant to SMC 15.43.030 (C): The
City's policy is to retain and preserve street trees whenever possible. Accordingly, street tree removal shall not be
permitted unless the Director determines that a street tree:
1. Is a hazardous tree;
2. Poses a public safety hazard;
3. Is in such a condition of poor health or poor vigor that removal is justified; or
4. Cannot be successfully retained, due to public or private construction or development conflicts.
Initial Assessment
1. Is the tree healthy and worthy of preservation?
□ Yes
□ No
Describe:_______________________________________________________________________
2. Poor Health – Is this tree in a condition of poor health or poor vigor that cannot be mitigated by any
means other than removal?
□ Yes
□ No
Describe:_______________________________________________________________________
3. Hazardous Tree— Defined in [CITY CODE CITATION] any tree or tree part that poses a high risk of
damage to persons using, or property located in the public place, as determined by the [AUTHORITY]
according to the tree hazard evaluation standards established by the International Society of
Arboriculture.
□ Yes
□ No
Describe:_______________________________________________________________________
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 K | P a g e
4. Minimum Standards—Is there enough space for a [6 foot wide sidewalk and a 5 foot wide] planting
strip?
□ Yes
□ No
Describe:_______________________________________________________________________
5. Public Safety Hazard—Does the tree present a public safety hazard that cannot be mitigated by any
means other than removal?
• Does the tree location obstruct the visibility for pedestrians, cyclists, and/or cars at an
intersection?
• Is the tree impacting a curb ramp such that it no longer meets City of [CITY] ADA requirements?
• Is the tree potentially impacting private property?
□ Yes
□ No
Recommendation for this tree:
□ –Remove Tree / Replace Sidewalk
A tree is identified to be removed if it is not healthy or if it is hazardous as identified in the Street Tree
Ordinance.
□ –Keep Tree and Maintain Sidewalk
A tree will be kept and the sidewalk will be maintained if a sidewalk of standard width and a tree pit of
standard width (at a minimum) can be installed or retained around a healthy tree.
□ –Evaluate Sidewalk and/or Tree Further
[DEPARTMENT] views trees and sidewalks as important public infrastructure assets. [DEPARTMENT]
intends to keep healthy trees and have accessible sidewalks. If standard widths cannot be met then
[DEPARTMENT] will take the time and resources to evaluate if alternative approaches (such as sidewalk
width reduction, alternative sidewalk materials, adjustments to the tree pit and/or tree root pruning) can
be used to retain a tree and provide an accessible sidewalk at problem locations.
NEXT STEPS
If Tree is REMOVED –Replace the removed tree with the minimum 2:1 replacement ratio. Identify if the
replacement trees can be located in the same location or on the same street as the removed tree. If not,
replacements should be planted as close to the removal as geographically feasible. Identify the estimated cost to
remove the tree(s), repair the sidewalk, and plant replacement trees.
If Tree is KEPT –Estimate the cost of the sidewalk repair that would achieve the desired lifecycle for the repair.
Estimate sidewalk and tree maintenance needs/costs and any maintenance to the tree that is being retained (e.g.,
root pruning, branch pruning, soil amendments).
If EVALUATE Further – Use Tree and Sidewalk Evaluation Form (IN DEVELOPMENT) and/or the tree risk
assessment should follow ISA TRAQ guidelines: http://www.isa‐
arbor.com/education/onlineresources/basictreeriskassessmentform.aspx
Arborist Engineer
Title Tile
Date Date
Use this space to draw a sketch of the location. Identify existing clearances from nearby
infrastructure.
Appendices L | P a g e
Alternative Solutions Toolkit Overview
MATERIAL
DESIGN
ROOT
TREE
Paving and Other Surface Materials
These materials can be used to create a walkable
surface or to delineate space for people and/or the
tree.
Infrastructure-Based Design Solutions
These design considerations can be employed to
support a tree and/or sidewalk.
Rootzone-Based Materials
These tools can support tree health and guide tree
growth below ground.
Tree-Based Solutions
These solutions are focused on tree selection and
tree maintenance.
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 M | P a g e
Table 28. Description of possible alternative solutions for tree and construction conflicts
TOOL
TYPE TOOLS PROACTIVE RESPONSIVE COST*
EXPECTED USEFUL
LIFE
$ $$ $$$ $$$$ Month Year Decade Century
MATERIAL
PAVING AND OTHER SURFACE
MATERIALS
Asphalt P R $-$$$ M Y D C
Expansion Joints P R $ M Y D C
Pavers P R $$-$$$ M Y D C
Pervious Concrete P R $$$-$$$$ M Y D C
Reinforced or Thicker Slab P R $$-$$$ M Y D C
Rockery / Wall P R $$-$$$$ M Y D C
Beveling P R $-$$ M Y D C
Porous Asphalt P R $-$$$ M Y D C
Shims P R $ M Y D C
Tree Guards and Tree Rails P R $$-$$$ M Y D C
Decomposed Granite P R $-$$ M Y D C
Mudjacking (Concrete Leveling) P R $$-$$$$ M Y D C
DESIGN
INFRASTRUCTURE-BASED
DESIGN SOLUTIONS
Monolithic Sidewalk P R $$$ M Y D C
Pavement Thickness P R $$$ M Y D C
Tree Pit Sizing P R $ M Y D C
Bridging P R $$$$ M Y D C
Curb Bulbs P R $$$-$$$$ M Y D C
Curb Realignment P R $$$-$$$$ M Y D C
Curving or Offset Sidewalk P R $$-$$$ M Y D C
Easement P R $-$$$ M Y D C
Suspended Pavement Systems P R $$$-$$$$ M Y D C
Lowered Sites P R $$$-$$$$ M Y D C
Soil Volume P R $-$$$ M Y D C
Appendices N | P a g e
TOOL
TYPE TOOLS PROACTIVE RESPONSIVE COST*
EXPECTED USEFUL
LIFE
$ $$ $$$ $$$$ Month Year Decade Century
ROOT
ROOTZONE-BASED MATERIALS
Mulch P R $ M Y D C
Root Barriers P R $ M Y D C
Continuous Trenches P R $$$ M Y D C
Foam Underlay P R $-$$ M Y D C
Modified Gravel Layer P R $ M Y D C
Root Paths P R $-$$ M Y D C
Soil Modification P R $-$$ M Y D C
Steel Plates P R $$-$$$ M Y D C
Structural Soils P R $$-$$$ M Y D C
Subsurface Aeration / Irrigation P R $$ M Y D C
TREE
TREE-BASED SOLUTIONS
City Forestry Street Tree List P R $ M Y D C
Corrective Pruning P R $-$$ M Y D C
Root Pruning P R $-$$ M Y D C
*General cost notes:
• Sidewalk material costs, when given in linear feet, assume 6-foot sidewalk width
• Costs are planning-level costs and will vary for actual construction
• Costs do not include design, permitting, or other "soft" costs
• Costs not included in tool costs but which would be necessary with use of some solutions include:
o Drainage structure and connection
o Curb ramps
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 O | P a g e
BEVELING POROUS ASPHALT SHIMS TREE GUARDS/RAILS
ASPHALT JOINTS PAVERS/RUBBER PERVIOUS CONCRETE
DECOMPOSED GRANITE MUDJACKING BRIDGING BULBOUTS
Figure 44. Example of alternative solutions for tree and construction conflicts
Appendices P | P a g e
CURB REALIGNMENT EASEMENT SUSPENDED PAVEMENT ROOT BARRIERS
CORRECTIVE PRUNING ROOT PRUNING ROOT SHAVING
FOAM UNDERLAY MOD. GRAVEL LAYER STRUCTURAL SOILS ROOT PATHS
Source of Material
Examples & Images:
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 Q | P a g e
APPENDIX C. GUIDANCE TO DEVELOP A TREE ADVISORY COMMITTEE
To increase the capacity and voice for residents in managing the trees in Renton, guidance is
provided for the City to consider the benefits of establishing a Community Tree Advisory
Committee. This document provides specific recommendations and considerations for the City
of Renton.
Overview
Forming a Community Tree Advisory Committee (TAC)— also referred to as a tree commission,
tree board, urban forestry commission, beautification committee, environmental advisory
committee, community forestry commission, among others depending on the jurisdiction — is
one step Renton can take to create and sustain an urban forestry program. The powers a nd
responsibilities of a Tree Advisory Committee are based on Washington statutes and are
assumed by the local government. By forming and empowering a tree commission, Renton can
provide an opportunity for important community decisions to include the perspectives of the
communities of Renton. The formation of the TAC can be a crucial element in developing
broad-based support for community trees and ensuring long-term success and growth of
Renton’s urban forestry program.
Proposed Responsibilities of the Tree Advisory Committee
The Tree Advisory Committee should reflect the values and standards of the community and
should help champion urban forestry efforts. The recommended roles and responsibilities of
Renton’s TAC could include the following:
❖ Periodic review of Urban Forestry Program activities.
❖ Participate in an advisory capacity for tree removal appeals processes.
❖ Act as a sounding board for administrative issues in urban forest management.
❖ Stimulate and help organize volunteer tree planting and maintenance events.
❖ Assist with a possible ‘Heritage’ or ‘Historic’ trees program.
❖ Support urban forest management generally in an advisory capacity.
❖ Help identify, facilitate and recommend solutions to tree-related community disputes.
The proposed responsibilities of the TAC would be customized to suit the task, but Renton
ordinances creating either the Senior Citizen Advisory Group or the Equity Commission could
serve as useful references.
Formation of the Tree Advisory Committee
Formation of the Tree Advisory Committee and development of a comprehensive urban forestry
program usually take place together. The creation of Renton’s TAC is recommended at this
stage due to the opportunities that have arisen during the development of the City’s current
Urban Forest Management Plan (UFMP). The UFMP project began in May 2021 and is anticipated
to be completed by February 2022 and throughout this planning effort, community members
and organizations have been educated and engaged to support the development of the UFMP.
This public engagement has increased awareness of and support for the City’s urban forestry
efforts. The engaged community members may now be interested in actively participating on
the TAC.
Renton’s citizens who have been active in public engagement activities for the Urban Forest
Management Plan can provide valuable insight on a TAC. The requirements relating to
membership of committees are identified in the City of Renton municipal code Title II
Commissions and Boards. Members shall be appointed by the mayor and approved by City
Council. It is recommended that the City of Renton identify and explore specific sectors of the
community to recruit diverse members of various backgrounds and experiences.
The following steps are recommended for Renton to organize citizens and form the Tree
Appendices R | P a g e
Advisory Committee:
❖ Hold informal meetings with concerned citizens and local officials to discuss ideas and
plans. Discuss with the City Attorney’s office legal requirements to establish a Tree
Advisory Committee.
❖ Organize interested citizens and informally outline opportunities for a TAC to address
and advise on specific occurrences or situations (such as tree failures, tree preservation,
tree removals, tree removal permit denials, pruning, sidewalk damage, or tree planting)
that have caused community conflict or liability. Describe benefits that are expected to
result from an organized tree program (such as lower community liability, higher real
estate values, more attractive commercial areas, healthier trees, and increased
community fellowship).
❖ Contact other communities with Tree Advisory Committees or other experts, such as the
Washington Community Forest Council, Extension Forestry, and the State of Washington
Urban and Community Forestry program for advice and support.
❖ Liaise with Forestry Staff. It can be the case that a staff member sits on the committee in
a non-voting capacity— this provides an important link to the municipal process.
❖ Identify and agree upon the powers, authority, and responsibilities of the TAC, through
meetings with municipal council members, officials, and the City Attorney’s office.
❖ Involve community members through public hearings and other opportunities for public
participation and response.
❖ Develop or rewrite the ordinance that legally establishes the TAC and defines its authority
and powers.
❖ Seek the council's approval of the ordinance according to the City’s procedure.
Establishment of the Tree Advisory Committee by Ordinance
Municipal ordinances establishing and empowering Tree Advisory Committees should contain
the following sections:
❖ Number of committee members,
❖ Experience or expertise required of members,
❖ Place of residence,
❖ Compensation, if any,
❖ Length of terms,
❖ Rotation of terms,
❖ Vacancies,
❖ Advisory duties,
❖ Primary focus areas.
Additionally, ordinances establishing Tree Advisory Committees can:
❖ Mandate a municipal arborist or forester position,
❖ Mandate and outline the creation of a municipal forestry master plan,
❖ Outline required standards and guidelines for tree planting and maintenance.
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 S | P a g e
Supporting the Tree Advisory Committee
❖ Consider training members through the Arbor Day Foundation’s
Tree Board University.
o An online training course consisting of eight courses:
1) Tree Board 101
2) Partnerships and Collaboration
3) Engaging in the Political Process
4) Community Forestry Planning
5) Communications and Marketing
6) Financing, Budgeting, Grants, Fundraising
7) Getting Things Done
8) Moving Forward
❖ Utilize additional resources such as the Arbor Day Foundation’s Tree
Board flier.
❖ Keep the Tree Advisory Committee informed of the progress in
implementing the Urban Forest Management Plan.
❖ Consider including a member(s) on the Urban Forest Management Plan implementation
team.
❖ Upon establishment the TAC should establish By-Laws to instill cooperation and success.
❖ Keep the TAC current on urban forestry research, technology, tools, and ideas.
❖ Communicate programs, events, strengths, challenges, and opportunities.
Summary
A Tree Advisory Committee for Renton’s urban forest can have a great impact on a community's
appearance and image as well as its public safety and comfort. Tree committees can help
champion comprehensive and expert programming to manage and sustain public trees. They
can help facilitate the provision of long-term, stable community involvement for a valuable,
long-lived resource. By forming the Tree Advisory Committee in Renton, the attractiveness of
the community and its quality of life and environment might be enhanced and further
sustained.
Appendices T | P a g e
APPENDIX D. 2021 URBAN FOREST AUDIT SYSTEM RESULTS
Urban Forest Audit Scoring Key
Not Practiced (0) In Development (1) Adopted Practice (2)
Management Policy
Category Component Evaluated Description or Criteria for Evaluation
1.00 Approved Policy
Statements Written policy statements approved by a governing body.
1.01 Climate Change
(Sustainability)
Also referred to as Sustainability. With reference to urban trees.
Addresses the long-term health and productivity of the natural
resource.
1.02 No Net Loss Can refer to trees, basal area, or canopy.
1.03 Risk Management Should reference: ANSI A300 Part 9, ISA BMP, and prioritization
funding mechanisms.
1.04 Tree Canopy Goals Overall community/campus goal, or by designated “zone”.
1.05 Tree Protection Construction and/or landscape maintenance.
1.06 Utility Utility pruning, planting, and installation policy (e.g. boring vs.
trenching).
1.07 Human Health – Physical &
Psychological
Recognizes and addresses the human health benefits of the
natural resource (e.g., exercise, air quality, stress management,
shade).
Could also include Urban Heat Island (UHI) policies.
1.08 Wildlife
Diversity/Habitat/Protection Mammals, birds, or reptiles.
1.09 Performance Monitoring
Recognizes the annual or biennial calculation of metrics (e.g. some
component of ecosystem services) for the purpose of tracking
management performance.
1.10 Ordinance (Private) Tree protection and management for trees on private property.
1.11 Ordinance (Public) Tree protection and management for public trees.
1.12 Development Standards
US Green Building Council’s LEED® rating systems (or similar
internationally)
LEED v4 BD+C (Sustainable Sites)
LEED 4 ND (Neighborhood Pattern & Design, Green Infrastructure)
ASLA’s SITES® Rating System
1.13 High-Conservation Value
Forests
Programs or policies for identification, acquisition, and/or
protection of groups of trees or forests that provide unique public
benefits.
1.14 Urban Interface (WUI) Programs or policies that improve management of the urban
interface for fire and/or invasive species.
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 U | P a g e
Capacity and Training
Category Component Evaluated Description or Criteria for Evaluation
2.00 Professional Management Provision for professional consultation.
2.01 Certified Arborist - Staff International Society of Arboriculture
2.02 Certified Arborist -
Contracted International Society of Arboriculture
2.03 Certified Arborist - Other
Resource International Society of Arboriculture
2.04
Other Professional -
Advising/directing UF
management
This could be a professional in an allied field like Landscape
Architecture.
2.05 Municipal Forestry Institute Graduate of Society of Municipal Arborist’s MFI program or similar
2.06 USFS Urban Forestry
Institute or similar Attendance at USFS UFI or similar
2.07 Campus/city arborist – ISA
CA instructor for CEUs Arborist routinely provides ISA CEU presentations/workshops.
2.08 Tree Board University or
similar On-line training modules from Oregon U&CF for Tree
Board/Advisory Council or similar
2.09 Organizational
Communications
Process, procedures, and protocol for cross-professional
communications within the organization (all departments
“touching” trees).
Appendices V | P a g e
Funding and Accounting
Category Component Evaluated Description or Criteria for Evaluation
3.00 Urban Forestry Budget
3.01 Budgeted Annually Budget authorized/required for tree board, tree maintenance,
and/or tree planting.
3.02 Contingency Budget
Process
A protocol is in place to prioritize urban forestry management
activities during budget shortfalls; e.g. during times of limited
funding for: 1) risk management, 2) young tree care, 3) mulching.
3.03 Funding Calculated from
Community Attribute
Budget in terms of per capita, per tree, or for performance (e.g. per
tree weighted by size class or age.
3.04 Funding Based on
Performance Monitoring
Budget connected with/based on ecosystem service (ES)
monitoring and performance.
3.05 Urban Forestry Line Item Is the budget specific to urban forest management?
3.06 Green Asset Accounting
Maintain green infrastructure data in the “unaudited
supplementary disclosure of an entity’s comprehensive annual
financial report (CAFR)”. GASB 34 implementation for
municipalities.
Authority
Category Component Evaluated Description or Criteria for Evaluation
4.00 Authority
4.01 Urban Forest Manager
Professional urban forest manager with authority over the
program and day-to-day activity. Including designated budget line
item.
4.02 Staff Authority Designated staff with authority over the program and day-to-day
activity. Including designated line item.
4.03 Communication Protocol
Established protocol and mechanism(s) for communication
among all members of the urban forest management
“community” in your municipality or organization (e.g. manager,
department under control, advisory board, finance, field
operations, public, NGOs, business community, developers).
4.04 Tree Board, Commission,
or Advisory Council
Establishes a board for public participation (advisory or with
authority).
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 W | P a g e
Inventories
Category Component Evaluated Description or Criteria for Evaluation
5.00 Inventories and
Assessments
5.01 Canopy Inventory (UTC) Periodic (≤5 year) canopy inventory and assessment. Public &
private.
5.02 Ecosystem Services
Recent (≤5 year) ecosystem services (ES) inventory & assessment?
Public: 100% or street trees; Public & Private: Sample; or Campus.
Or, are ES calculated annually or biennially based on partial re-
inventory and projected growth as a monitoring tool.
5.03 Public Trees Evaluate below
5.04 Street Trees Is there a recent (5 year) inventory?
5.05 Parks/Riparian Areas Is there a recent (5 year) inventory?
5.06 Other Public Trees Public facility landscaped areas, Industrial parks, green space.
5.07 Continuous inventory on a
cycle (≤5 years; i.e. panel)
Partial re-inventory to support continuous forest inventory, growth
projections,
and the calculation of ecosystem services for the purpose of long-
term monitoring of urban forest management performance (e.g.
carbon or leaf surface).
5.08 Private Trees Evaluate below
5.09 Campus (Educational) Is there a recent (5 year) inventory?
5.10 Corporate Is there a recent (5 year) inventory?
5.11 Other Private Property Is there a recent (5 year) inventory?
5.12
Continuous inventory on a
cycle (≤5 years; i.e. panel),
inventory software
Partial re-inventory to support continuous forest inventory, growth
projections, and the calculation of ecosystem services for the
purpose of long-term monitoring of urban forest management
performance (e.g. carbon or leaf surface).
5.13 Green Stormwater
Infrastructure (GSI)
BMP stormwater mitigation practices and locations (e.g.
Washington DC)
5.14 Spatial
Inventory data includes Lat/Long (i.e. GIS). Should address the
spatial relationship between the natural resource and people (i.e.
residents, visitors, activities) that would help manage the resource
for benefits associated with proximity (air quality,
recreation, stress mitigation, improved educational opportunity).
5.15 Maintenance and Planting
Records Maintained
Planting details (nursery, species, size, cost, contractor, etc.)
maintained with inventory or as separate database or
recordkeeping system. Also pruning and removal histories.
Appendices X | P a g e
Plans
Category Component Evaluated Description or Criteria for Evaluation
6.00 Management Planning
Activities
6.01 Annual Maintenance
Calendar
An annual calendar that defines typical activity by season. To
support scheduling.
6.02 Public Trees Evaluate below
6.03 Street Tree Management Is there a recent (5 year) plan for street trees?
6.04 Parks/Riparian Area
Management Is there a recent (5 year) plan ?
6.05 Other Public Trees Public facility landscaped areas, Industrial parks, green space.
6.06 Private Trees Evaluate below
6.07 Campus (Educational) Is there a recent (5 year) plan for Campus trees?
6.08 Corporate Is there a recent (5 year) plan?
6.09 Other Private Property Is there a recent (5 year) plan?
6.10 Green Infrastructure Is there a plan for green infrastructure (i.e. nodes & linkages)?
Large-scale projects.
6.11 Other Written Plans Other natural resource plans (e.g. tree canopy). May be a
component of another plan.
6.12 Tree Planting Is there a recent (3 year) tree planting plan? ). May be a
component of another plan.
6.13 UF as Part of a
Comprehensive Plan
Is any UF management plan referenced in the comprehensive plan
(i.e. county or municipality) or master plan (i.e. Campus)?
6.14
Urban Forest Planning and
Management Criteria and
Performance Indicators
Criteria and indicators based on A Model of Urban Forest
Sustainability (Clark, J.R., Matheny, N.P., Cross, G., and Wake, V.
1997 Journal of Arboriculture.) or on work of W.A. Kenney, P.J.E. van
Wassenaer, and A.L. Satel in Criteria and indicators for strategic
urban forest planning and management. (2011)
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 Y | P a g e
Risk Management
Category Component Evaluated Description or Criteria for Evaluation
7.00 Risk Management
Activities
7.01 TRAQ Attained At least one staff or consultant is TRAQ.
7.02 Annual Level 1 (ANSI A300
Part 9 & ISA BMP) All trees in high occupancy areas visited annually.
7.03 Mitigation Prioritization A protocol for prioritizing mitigation following Level 1 and Level 2
assessments. Reflects the controlling agency’s threshold for risk.
7.04 Occupancy Areas Mapped Has TRAQ staff/consultant discussed/mapped occupancy levels
with controlling authority?
7.05 Recordkeeping, Reporting,
and Communications
A process has been put in place to maintain records on requests,
inspections, evaluations, and mitigation of risk; and on the
communications among the managers related to those risk
assessments.
7.06 Standard of Care Adopted Controlling authority has adopted a Standard of Care (SOC) or risk
management policy.
7.07 Tree Risk Specification
Is there a written specification that meets requirements of ANSI
A300 (Part 9)? And, has it been discussed with the controlling
authority with relevance to the controlling authority’s threshold for
acceptable risk?
7.08 Urban Tree Risk
Management
The community has prepared and follows a comprehensive
program for urban tree risk management.
7.09 Invasive Management Plan to address and manage invasive: plants, insects, and disease.
Appendices Z | P a g e
Disaster Planning
Category Component Evaluated Description or Criteria for Evaluation
8.00 Disaster Planning
Activities
8.01 Response/Recovery
Mechanism
Staff knowledge of the municipality’s protocol for requesting
disaster resources through the county or state with access to
mutual aid and EMAC.
8.02 Urban Forestry as part of
the County Disaster Plan
The UF plan (8.3) is incorporated into the county/municipal
disaster plan; specifically in reference to debris management and
risk mitigation.
8.03 Urban Forestry Disaster Plan A separate/specific plan within the urban forestry management
program (i.e. who to call, priorities).
8.04 Pre-disaster Contracts Contracts are in place for critical needs.
8.05 Mitigation Plan A mitigation plan has been developed for pre-disaster, recovery,
and post-disaster.
8.06 EMAC Mission Ready
Packages (MRP)
Municipality has published disaster resources with state EM and
participates in inter-state Mutual Aid to support Urban Forest
Strike Teams (UFST).
8.07 Urban Forest Strike Team Participation in the UFST project.
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 AA | P a g e
Standards and Best Management Practices
Category Component Evaluated Description or Criteria for Evaluation
9.00 ANSI Standard & BMP
Activities
9.01 ANSI Standards
Reference and adherence to ANSI Standards for arboricultural
practices (A300), safety (Z133), or Nursery Stock (ANSI Z60.1) (any or
all).
9.02 Ages/Diameter Distribution Specific management for the development of an age-diverse tree
population
9.03 Arborist Standards Standards of practice for arborists (i.e. Certification).
9.04 Best Management Practices
(BMPs)
Establishes or references tree maintenance BMPs (i.e. written
comprehensive standards & standards).
9.05 Fertilization and Mulching Fertilization or mulching standards required for conserved &
planted trees.
9.06 Lightning Protection
Systems BMP written to the ANSI A300 Standard.
9.07 Planting Planting and transplanting standards required/specified.
9.08 Pruning Pruning standards required for conserved & planted trees.
9.09 Removal Infrastructure damage, stump grinding, etc.
9.10 Support Systems (Guying
and Bracing) BMP written to the ANSI A300 Standard.
9.11 Tree Risk Tree risk assessment procedures; ISA BMP or equivalent.
9.12 Construction Management
Standards
Written standards for: tree protection, trenching/boring in CRZs,
pre-construction mulching, root or limb pruning, watering (any or
all).
9.13 Design Standards Standards for design that specifically require trees; standards for
tree placement (i.e. location), soil treatment, and/or drainage.
9.14 Genus/Species Diversity Suggests or requires diversity of plant material.
9.15 Green Stormwater
Infrastructure (GSI)
BMPs for site level GI practices like rain gardens and swales. Small-
scale projects.
9.16 Inventory Data Collection Community has adopted or developed applicable standards for
local urban tree inventory data collection to support QA/QC.
9.17 Minimum Planting Volume Minimum required root zone volume.
Appendices BB | P a g e
Standards and Best Management Practices (continued)
Category Component Evaluated Description or Criteria for Evaluation
9.00 ANSI Standard & BMP
Activities
9.18 Minimum Tree Size Minimum caliper for tree replacements, and/or minimum size of
existing trees to receive tree density or canopy credit.
9.19 Root Protection Zone (CRZ) Defines adequate root protection zone; Critical Root Zone (CRZ).
9.20 Safety Safety logs, trainings, reference to ANSI Z133 Safety Standard
9.21 Topping Prohibits topping or other internodal cuts (public & private).
9.22 Tree Species List
Identifies and publishes a list of the most desirable,
recommended, and/or preferred species (may include native and
non-native species); alternatively, a list of species prohibited.
9.23 Tree Quality Standards Written standards for tree selection at nursery in addition to Z60.1.
9.24 Utility Right-of-Way ( ROW)
Management
Requirements for planting, pruning, and/or removal of trees within
a utility ROW.
9.25 Urban Agriculture Enabled urban food forestry practices.
9.26 Wood Utilization Larger diameter material is processed for wood products.
9.27 Third-party forest products
certification compliance
Examples: American Tree Farm System (ATFS), Forest Stewardship
Council™ (FSC®)
9.28 Energy generation Local or regional use of chips or other woody debris for co-
generation facilities.
9.29 Composting of Leaf and/or
Other Woody Debris
Leaves and small woody debris are captured and used on-site or
processed by someone by composting for reuse.
9.30 Watering Standards
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 CC | P a g e
Community
Category Component Evaluated Description or Criteria for Evaluation
10.00 Activities that Build
Community
10.01 Social Media Website or
Similar
Does your community/campus use social media platforms or
similar to document and publicize your urban forestry program,
activity, or events?
10.02 Education The urban forest is used as an educational laboratory for class
activity; Kids in the Woods, PLT, high school, or college level.
10.03 Private Property Tree
Program Does your community sponsor this program locally?
10.04 Tree Inventory and
Management Software
Public access to the community tree resource via an on-line
mapping program (i.e. any Web Map Service; WMS).
10.05 Public Perception
Is public management consistent with private property
requirements for tree protections and care? Does the
Campus/public tree management reflect neighborhood norms?
10.06 Recognition Programs Programs that raise awareness of trees or that use trees to connect
the community to significant events or activities.
10.07 Arbor Day Celebration Whether or not associated with Tree City USA.
10.08 Arboretum designation Internal or third party arboretum designation.
10.09 Significant trees For example: size, history.
10.10 Memorial/Honorarium Tree planting or tree care programs than honor/memorialize
individuals, organizations, or events.
10.11 Social Media Does your community/campus make use of Twitter, Facebook,
Blogs for internal or external outreach?
10.12 Active Communications Press releases, regular news articles (print), “State of the Urban
Forest” reports, periodic analysis of threats and opportunities.
10.13 Tree Care Are volunteers trained and used for basic tree care (e.g. mulching,
pruning, planting).
10.14 Tree Campus USA®, Tree
City USA®, Tree Line USA®
Community/campus meets current qualifications for any of these
programs.
10.15 Volunteer Opportunities Ad hoc or scheduled. Any/all age groups. Tree Campus USA
student activities.
Appendices DD | P a g e
Green Asset Evaluation
Category Component Evaluated Description or Criteria for Evaluation
11.00 Observed Outcomes
(Activity, Health)
11.01 Deadwood Look for evidence of periodic or ad-hoc deadwood removal (i.e.
lack of dead limbs ≥ 2” in the trees or on the ground).
11.02 Genus Diversity
No genera exceed 20% of population; make specific observations
for Acer, Quercus, Fraxinus, Ulmus and other local species of
concern.
11.03 Mature Tree Care Mature trees are retained in the landscape, and are of acceptable
risk; i.e. veteran tree management.
11.04 Mulching Evidence of adequate (i.e. spatial extent, depth, and material) roots
zone mulching for all age classes.
11.05 Planting Site Volume
Optimization
Are species & sites matched for optimization of above ground
canopy; right tree in the right spot concept.
11.06 Rooting Volume
Optimization
Are species & sites matched for optimization for below ground
rooting volume; right tree in the right spot concept.
11.07 Species Diversity
No species/cultivars exceed 10% of population; make specific
observations for Acer, Quercus, Fraxinus, Ulmus and other local
genera of concern. Also evaluate the role of regionally local native
species.
11.08 Soil Compaction
Observe evidence of soil compaction by users or staff during
maintenance. Include “desire” lines and construction activity at
time of evaluation.
11.09 Tree Health Rate the overall tree health in all size (age) classes; look for crown
dieback, decay, foliage density & color.
11.10 Young Tree Pruning
Look for evidence of periodic (e.g. every 3 years to year 9) structural
pruning (e.g. subordination cuts, dominant central leader, co-
dominant stems lower that 20’).
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 EE | P a g e
APPENDIX E. RISK TREE MANAGEMENT PLAN
CITY OF RENTON,
WASHINGTON
COMMUNITY SERVICES
DEPARTMENT
URBAN FORESTRY &
NATURAL RESOURCES
AUGUST 2020
TREE RISK
MANAGEMENT
PLAN
Appendices FF | P a g e
Trees are a valuable asset to the community of Renton, beautifying our city and linking
us to the natural environment. They also provide other benefits such as purifying our
air, reducing energy consumption and costs, and reducing storm water runoff.
However, a structurally defective tree in the urban setting can present a safety risk to
people and property. Dying and defective trees can also increase wildfire risks - less of
a concern in the South Puget Sound but one to be aware of in a changing climate.
City of Renton Forestry is responsible for managing
trees located on city street rights-of-way (street trees),
parks, natural areas and city owned property. One of
these responsibilities includes reducing the risks trees
can pose to people and property. This is accomplished
by identifying and evaluating defective city trees,
assessing and quantifying the safety risks and taking
the appropriate actions to reduce these risks. The City
of Renton Urban Forestry Management Plan defines
this process as Hazard Tree Management. Renton’s
urban forest has grown since the first management
plan in 2011 and there have been advances and
changes in arboriculture; some as simple as dropping
the terminology including “hazard” in favor of “risk”.
This document is part of a new update to this
management process and is redefined as a Tree Risk
Management Plan.
The purpose of this document is to inform the public of the City’s Tree Risk
Management Plan. This plan provides guidelines, procedures and practices in the
management of city trees that may present a safety risk to people and property.
The city has actively managed risk trees for over 12 years with a concerted effort
beginning in 2009. At that time, the city recognized the need to develop a long-range
plan for the maintenance of the urban forest. To that end, more management
information regarding Renton’s urban forest would be required and the city’s first
public tree inventory was created. This inventory was updated in 2020. This document
is the city’s first specified risk tree management plan.
INTRODUCTION
RISK TREE MANAGEMENT IN RENTON
HISTORY
Figure 1. An Oak tree in Maplewood Park
dropped a 70' foot long 2' foot diameter
branch during a hot day on an afternoon
in late July of 2020
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 GG | P a g e
In 2011, the city published and City Council officially adopted the City of Renton
Community and Urban Forest Development Plan. This plan did not include risk tree
management specifically, but one of four major stated goals included increasing public
safety by better management of the urban forest. Best management practice
recommends clear definitions of tree hazards and use of International Society of
Arboriculture (ISA) evaluation processes and forms for assessing risk trees. A risk plan
should also explain a process of designating certain trees as “Monitor” trees; trees to be
evaluated for tree risks once per year and after storm events.
This process could serve the city well and the current City Forester recognized the need for a
comprehensive risk tree management plan. There are new standards and tools for assessing risk
trees and Renton’s urban forest is growing and aging. New assessmen t technologies such as
resistance drill testing and sonic imaging could become part of the City Forester’s toolkit to
assess decay pockets and the internal structural integrity of trees.
The ISA has developed the new Tree Risk Assessment methodology, which differed from past
evaluation techniques and has been standardized in the tree care industry. These changes and
challenges in managing Renton’s urban forest, advancements in technology and arboricultural
practices, and the forestry program's continuing efforts to provide the best urban forestry
management services for the city brings us to today and the 2020 Tree Risk Management Plan.
One of the unique challenges of managing Renton’s
urban forest stems in part from the nature of trees in the
Pacific Northwest - they grow tall here. Captain Renton,
the city's namesake, made his fortune from timber
harvested in the area, especially Douglas Fir trees. Small
pockets of remnant stands of second growth trees can still
be seen even today at the edge of new developments.
They can be more prone to branch failures than other tree
species during storms. In addition to large tree size, the
prevalence of particular species in the urban forest
population presents more opportunities for possible
damages and consequences as a result of the failure of a
tree or tree part. Other native species like Big Leaf Maples
and Black Cottonwoods can also be problematic as they
are also large trees and are prone to decay. They comprise
a large proportion of the public tree population, especially
in natural areas. We also see large specimen trees like Pin
Oaks, Tulip Trees, Cedars and Sycamores on city streets
which require thoughtful management.
Therein lies the challenge and one of the justifications for a clearly defined tree risk
management strategy. The result is that maintaining healthy tree populations requires more
intensive management versus less “problematic” trees. This more intensive management comes
at little higher cost to the community as well as accepting a little higher degree of tree related
risk.
RENTON’S LOGGING LEGACY AND 'TALL TREES' IN THE PACIFIC NORTHWEST
Figure 2. Typical group of 'urban' Douglas Fir
trees on NE Sunset Blvd.
Appendices HH | P a g e
Beyond adopted city policy, best management practice for risk trees should be no exception.
The City of Renton Urban and Community Forestry Development Plan adopted by City Council
established improving public safety as an important goal. The following procedures have been
developed to guide the city in the implementation of the Tree Risk Management Plan in the
next iteration of the city's 10-year urban forest management plan in 2021.
A potential risk tree will be evaluated by the City
Forester. The tree will be evaluated using the
International Society of Arboriculture’s (ISA) Tree Risk
Assessment Methodology (www.isa-arbor.com). This is
the industry standard for evaluating a risk tree. It
includes evaluating potential targets of a tree failure,
defects in the tree that may fail, the probability the
defect(s) may fail and finally the potential
consequences if the defective tree part fails. The
culmination of the assessment results in a Risk Rating;
Low, Moderate, High or Severe. Other factors that are
considered in determining the risk include; the
occupancy rate of a target in the impact zone, whether
a tree a strong or weak-wooded tree species, the
possible exposure of the tree to strong wind events, a
history of failures, topography and wildfire risk in a
potential future wildfire control area.
A risk tree is defined by the following industry terms.
➢ A Risk Tree is a tree with a defect present that has a likelihood of failure of Proba ble or
Imminent, a target occupancy rate greater than Rare and/or located in a moderate or
high wildfire risk area as determined by the City Forester.
PRACTICES
RISK TREE
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 II | P a g e
The city is responsible for managing all trees
located on public property. These include trees
located on city street right-of- ways (street
trees), parks natural areas and other city
properties. However, trees are living, growing
organisms that do not adhere to our people-
made boundaries. A small young tree
beginning its life clearly on a property, grows in
diameter with age and may grow over a
property line. In these cases of “border trees”, is
it the city’s or the private property owner’s
responsibility to manage the tree? The
following guidelines define a City Tree and the
responsibility for management of city/private
property border trees.
➢ The city will review the management
responsibility of any tree with at least
half of its trunk diameter measured at
4.5 feet above grade located on a city
right-of-way, easement or property.
o If necessary, a professional survey will be performed to provide clarification.
o In cases where there is clearly mutual responsibility, the city will work with the
property owner to reach a mutually acceptable arrangement.
There are trees located on private property that may pose an unacceptable risk to city property
or the right-of- way. If the city identifies a risk tree on private property or is informed of a risk
tree on private property, the following guidelines and collaboration with Code Compliance will
direct city action.
➢ A risk tree located on private property, as determined by the City Forester, will be
mitigated by the property owner or the city through a code compliance notice and order
process as defined in the City of Renton Code.
o In general, it includes a process of notifying the property owner and agreeing on
mitigation strategy within a given time frame.
RISK TREES LOCATED ON PRIVATE PROPERTY
CITY TREE
Figure 3. Example of a "border tree".
Appendices JJ | P a g e
In a natural setting trees die or fall creating space
for a new tree to grow in its place. In the urban
setting, it is people that must manage this
process. Dead, diseased or declining trees need
to be removed when they become an
unacceptable risk. People must plant trees to
replace removed trees. The city values all trees,
however at a certain point tree removal may be
the best management practice to reduce risks to
people and property, protect the urban forest
from insect pests and disease, unacceptable
wildfire risks and introduce renewal by planting
replacement trees. The following tree removal
guidelines will help direct public tree removal
decisions in the City of Renton.
➢ A city tree will only be removed if it is an
imminent threat to public safety , dead,
dying, diseased, surpassed its service life, or in conflict with a more important city project
as determined by the City Forester
➢ Tree Removal Notification Process
o Written notice is sent to adjacent property owners and residents of impending
tree work
o If needed, a tree removal notice stating the removal reasons will be posted by the
City Forester on the tree prior to the scheduled removal.
o If necessary, the City Forester will notify the Community Services Administrator,
the Mayor and City Council when a tree deemed of particular importance by the
City Forester is removed.
There are two ways Risk Trees are identified by the city; random observation and periodic
inspections.
The primary way risk trees are identified is through the city’s periodic tree pruning and inventory
programs. The goal is that each year 1/6th of the city’s trees in a particular geographic area or
planning district are pruned. Prior to the actual pruning, City Forestry performs a basic w alk
around inspection of trees in the scheduled area. Through this inspection process Risk Trees
may be identified. Further, as the pruning work is being completed on a tree, problems may be
identified by the pruner and it is their responsibility to notify City Forestry for further evaluation.
The City may also periodically perform a complete inventory of city trees or a special project
that may reveal a Risk Tree.
TREE REMOVAL
Figure 4. "Renewal of the urban forest". Replacement
tree planting in the downtown core.
IDENTIFICATION OF RISK TREES
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 KK | P a g e
There are cases where a city staff person, by
chance observation, identifies a potential
risk tree during their normal work activities.
A city forestry crew or contractor may be
pruning a tree and identify a problem. A
city staff person may notice a problem with
a tree. The inspection of a request for
service from the public may reveal a
potential risk tree.
Once a potential Risk Tree is identified the following procedures are implemented.
1. A Tree Risk Assessment is scheduled for the tree of concern.
2. The tree receives a Basic Tree Risk Assessment resulting in one of three of the outcomes.
a. Arboricultural treatments to mitigate the risks of defective tree part(s) will be
scheduled and completed, up to and including complete tree removal.
b. The tree will be scheduled for an advanced tree risk assessment.
c. The tree will be placed on the Risk Tree Monitoring Program.
As described above, an International Society of Arboriculture (ISA) Tree
Risk Assessment is the industry standard for assessing risk trees and
quantifying tree risk. In addition to detailing the methodology for
performing a Tree Risk Assessment, the ISA qualifies arborists to
perform a Tree Risk Assessment (http://www.isa-
arbor.com/certification/becomeQualified/becomeQualified.aspx). This
includes a training and testing program whereby upon the successful
completion of the program, an arborist is given the designation of Tree
Risk Assessment Qualified. All Tree Risk Assessments performed as part
of this program are performed by ISA Tree Risk Assessment Qualified
arborists.
Figure 5. Conks (fungal fruiting bodies) like the one
pictured here are an indicator of decay working in the
tree. In this case, the Ganoderma fungus decayed the
base of this aspen resulting in the tree failing.
in the tree failing.
HOW RISK TREES ARE MANAGED
TREE RISK ASSESSMENT
Appendices LL | P a g e
TREE PRUNING
The city’s standard tree pruning specifications
include the pruning of defective branches that
may pose an unacceptable risk of failing. A tree
pruner will be directed to prune the defective
branch(s) from the tree and as a result reduce the
risks of these defective branches failing. In some
cases, a more aggressive pruning practice called
“Reduction” pruning may be specified. Reduction
pruning includes the arboriculturally correct
practice of pruning the terminal portions of
scaffold and lateral branches to shorten the
length of the branches, spread of the tree, and
height of the tree. This treatment is used in cases
where there may be significant root or trunk
defects, or multiple scaffold branch defects.
Shortening the length of branches and/or the
height of the tree increases the amount of force
that is required to break a tree part and as a result
reduces the probability and risk the tree part will
fail. For large specimen trees which still retain
ecosystem value should they be stabilized despite
damage suffered, additional mitigation strategies
like cabling and bracing may be considered.
ADVANCED TREE RISK ASSESSMENT
A Basic Tree Risk Assessment is the first assessment performed after a potential risk tree is
identified. The basic assessment is completed from the ground and is primarily a visual
assessment. If the City Forester finds it is needed, then an Advanced Tree Risk Assessment will
be performed on the tree. This may include an inspection with an aerial lift truck and possibly
the use of advanced diagnostic tools such as a Resistograph and a Tomograph.
TREE RISK MITIGATION ARBORICULTURAL TREATMENTS & PRACT ICES
Figure 6. To safely retain this Oak tree, reduction
pruning and cabling was performed to reduce the risk of
further failure.
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 MM | P a g e
RESISTOGRAPH & TOMOGRAPH USES
Decay is very common in trees and particularly in
older trees. The amount of decay in a tree part or
more importantly the amount of soundwood
around a decayed tree part is the most important
variable in assessing the probability that a decayed
tree part may fail. The Resistograph and
Tomograph are two tools used to measure
soundwood and decay present in a tree part. Both
of these tools provide more information for
assessing the risk a tree part may fail. The findings
these tools provide do not provide the “end all”
answer to what management treatment should be
taken. They do provide more information for the
assessor to quantify failure risk and the final
management decision to be taken is a culmination
of the findings of these tests and other conditions
present with the tree.
RESISTOGRAPH
A Resistograph drills into the wood of a tree part and measures and records the resistance being
applied on the drill bit as it drills into the tree part. The result is a visual measurement of the
“sound” and “unsound” wood where the tree part was drilled.
Figure 7. Tomograph measurements being taken
on a tree in Jones Park, Renton, Washington.
Figure 8. Resistograph tape showing the thickness of sound wood.
Appendices NN | P a g e
TOMOGRAPH
A Tomograph uses soundwaves to
measure the “soundness” of a tree part.
Unlike the Resistograph, the Tomograph
provides a graphic representation of the
“soundness” of the wood around the
whole tree part measured, is a more
accurate measure and provides more
information with which to make a
probability of failure judgement.
RISK TREE MONITORING PROGRAM
Risk Trees that have an ISA Risk Rating of Moderate or higher, even after arboricultural
treatments have been completed, will be assigned to the city’s Risk Tree Monitoring Program.
Using the city’s computerized tree inventory, each of these trees will be designated as Risk
Monitor trees. Each of these trees will receive a Tree Risk Assessment every year. The findings of
the annual assessment will direct further action such as arboricultural treatments, advanced
tree risk assessment, retention on the Tree Risk Monitoring Program or if the condition of the
tree warrants, removal.
TREE REMOVAL
Ultimately a tree may have declined or may have been damaged to a point that removal and
planting a new tree is the best management decision.
Figure 9. Tomograph chart illustrating the
"soundness" of the tree part measured.
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 OO | P a g e
If you see a tree that you believe may pose a risk to public safety report your concern to City
Forestry in the following ways. Be prepared to provide the address and general location of the
tree of concern. The tree will be inspected by City Forestry and inform you of the findings.
➢ Call the Forestry Division at (425) 430-6601 to report your concern.
➢ Post a request to the city via the Renton Responds app.
➢ Send the City Forester an email via the City’s website by going to:
(www.rentonwa.gov/urbanforestry) and navigate down to the "Request Tree Assistance”.
HOW CAN YOU HELP?
Appendices PP | P a g e
• Andrew G. Pleninger (Consulting Arborist, Aspen Tree Service) and Ben Carlsen (Natural
Resource Manager, City of Aspen): coauthors of the original document from which this
risk plan was adapted.
• International Society of Arboriculture, Champlain, IL. Publication illustrations on pages 3
& 5.
• Photos on cover page and in figures 1,2,4,6 & 7 courtesy of Ian Gray, Renton Urban Forestry
& Natural Resources Manager, August 2020.
• Photos in figures 3 &5 courtesy of Ben Carlsen and Andrew Pleninger.
REFERENCES & ACKNOWLEDGEMENTS
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 QQ | P a g e
APPENDIX F. URBAN FOREST PEST READY ASSESSMENT
The Washington State Urban Forest Pest Readiness Playbook provides a set of actions that
towns, cities, counties, and urban forestry programs should take to address the threat of forest
pests. The purpose of the playbook is to close a gap in readiness and response capabilities
between community leaders managing urban forests and state and federal responders. After
using the playbook a city should have an understanding of your progr am’s preparedness,
documentation of what is known, and a path forward for improving pest readiness capabilities.
Initial funding for the Urban Forest Pest Readiness Playbook was provided by U.S. Department
of Agriculture Animal and Plant Health Inspection Service Plant Protection and Quarantine.
The resource is available at www.invasivespecies.wa.gov and an interactive worksheet was
provided as part of the Urban Forest Management Plan Project. The following provides the
framework of the Urban Forest Pest Ready Assessment section of the playbook. The playbook
should be utilized during and after completing the assessment to develop actions specific to
the evaluation.
Table 29. Urban Forest Pest Ready Assessment from the WA State Urban Forest Pest Readiness Playbook
Urban Forest Pest Ready Assessment
Understanding Risk
# Question Yes Points No/Not Sure?
Tree Resources
1a Has your community ever conducted a tree canopy
analysis?
1
See Action 6 in
the Playbook
1b
Has your city ever performed or does your city currently
have a tree-by-tree inventory containing data on
individual trees' species, sizes, conditions, and locations?
3
1c Is the inventory less than 10 years old?
1
1d Is the inventory less than 5 years old?
1
1e Does your inventory data include all or a significant
majority of all managed street and park trees? 2
1f Is your inventory held in a geospatial database with
location data?
2
1g Is your data able to be shared with others outside your
organization?
2
Pests of Concern
2
Have you identified priority pest species that are a
concern for your community based on an
understanding of common tree species in your urban
canopy?
1 See Action 3 in
the Playbook
Risk Analysis
3
Have you considered neighboring jurisdictions and/or
nearby natural resource economies like agriculture and
forestry as part of your assessment of priority pests?
1 See Action 7 in
the Playbook
Appendices RR | P a g e
Pest Pathways
Do you have an understanding of local hot spots for
pest introduction to your community including (check
yes if no hot spots exist):
4a
Locations where there is an influx of new residents or
popular destinations for out-of-state visitors
1
See Action 4 in
the Playbook
Transportation corridors and storage facilities for
commercial movement of forest and agriculture
products
1
Commercial ports (check yes if there are no
commercial posts)
1
4b
Have you documented the locations and
supplementary information about size of these pest
introduction hot spots?
1
4c Has your community identified trees or locations that
are particularly pest vulnerable?
1
Pest Prevention
5a Does your city staff use Best Management Practices to
prevent the spread and introduction of pests?
1
See Action 13
in the
Playbook 5b
Do you or partners provide training for local contractors
on tree care or Best Management Practices to prevent
the spread and introductions of pests?
1
Actions 3, 4, 6, 7, 13
Understanding risk subtotal 0 of 21
Capacity to Support a Response
# Question Yes Points No/Not Sure?
Emergency Preparedness
1 Do you have one or more staff that have been trained in
Incident Command Systems (ICS)?
1 See Action 18 in
the Playbook
Response Experience
2a Have you participated in an invasive forest pest response
in the last ~20 years?
1 See Action 17 &
20 in the
Playbook 2b
Do you know the basic components of a pest response
that a lead action entity would run in the event of a pest
confirmation?
2
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 SS | P a g e
Know Who to Call
3
Have you integrated the contact information for USDA-
APHISPPQ, USDA Forest Service, Washington Invasive
Species Council, Washington Department of Natural
Resources, Washington Department of Agriculture
and/or Washington State University into your own
systems so that a team member can easily know who to
call if a pest is detected in your area?
2
See Detection &
Reporting
Section in the
Playbook
Supporting Organizations
4a
Have you worked with Washington Invasive Species
Council, Washington State Department of Agriculture, or
Washington State Department of Natural Resources
state agency staff in the past to support your program
(could include training, consultation, workshops, grants,
one-on-one discussions)?
1 See Playbook
overview
4b Do you know which partners and stakeholders to engage
in order to garner support for a response?
1 See Action 9 in
the Playbook
Sufficient Funding
5 Do you know what funding options, both internal and
external, are available to you to respond to a pest?
1
See Action 5
in the
Playbook
Tree Management
Are you actively enhancing your managed street trees,
parks, and natural areas:
6
To prevent invasive species establishment 1
See Action 16
& 19 in the
Playbook
To diversity tree plantings 1
To restore areas after significant tree removal (for
example removal of damaged trees, invasive trees,
hazard trees, or a forest pest response)
1
Actions 5, 9, 16, 17, 18, 19, 20
Capacity to Support a Response subtotal 0 of 12
Ability to Expedite Informed Decision-Making
# Question Yes Points No/Not Sure?
Urban Forestry Staff
1a Do you have a staff person(s) or department(s)
responsible for urban tree management?
1 See Action 1
in the
Playbook 1b
Would you consider most of your non-urban forestry-
related departments to be informed on how their work
impacts your urban forests?
1
Appendices TT | P a g e
Local Authority
Do you have any urban forestry management:
2a
Plan(s) 1 See Action 2
in the
Playbook
Policies 1
City Code 2
2b Does your urban forestry management plan, policy, or
codes include information on pest management? 3 See Action 12
of the Playbook
Permitting Processes
3
Are you familiar with permitting processes regarding (+1
for at least 4 of 7):
• Public involvement/notices
• Environmental and water quality
• Endangered species
• Property access requirements
• Pesticide registrations and applicator licenses
• Plant quarantine compliance
• Waste management practices
• Historical site/archaeological permitting
1
See Action
8 & 15
in the Playbook
Leadership
4
Do you have elected officials currently serving that have
demonstrated concern for urban forest pests or invested
in urban forest pest-related initiatives?
3 See Action 11
in the Playbook
Actions 1, 2, 8, 11, 12, 15
Ability to Expedite Informed Decision-Making subtotal 0 of 13
Community Support to Expand Your Impact
# Question Yes Points No/Not Sure?
Diverse Team
1a Do you have experience bringing together diverse groups
of stakeholders across departments and topics?
1
See Action 9
in the Playbook
Do you have access to people with the following
expertise or role involved in this assessment (+1 for each
category filled):
1b
Tree or urban forest expert 1
City planner 1
Tree care professional or other community stakeholders 1
Renton, WA 10-year Urban Forest Management Plan Update Jan2022 UU | P a g e
Messaging
2
Do you know the appropriate messaging and languages/
channels/forums to use when communicating with the
populations and neighborhoods most likely to be
impacted by a pest detection?
1 See Action 10
in the Playbook
Public Awareness
3
Do you have information in public outreach materials
that you distribute that covers the issues and risk of
urban forest pests?
1 See Action 10
in the Playbook
Early Detection
4
Do you promote the implementation of and recruitment
to early pest detection network (such as Master
Gardeners, Washington Pest Watch)?
2 See Action 14
in the Playbook
Actions 9, 10, 14
Community Support subtotal 0 of 8
Urban Forest Pest Ready Scorecard Subtotal Total Bench-
mark
Understanding Risk 0 of 21 12
Capacity to Support a Response 0 of 12 8
Ability to Expedite Informed Decision-Making 0 of 13 7
Community Support to Expand Your Impact 0 of 8 5
Appendices VV | P a g e
APPENDIX G. REFERENCES
Kellert, S.R., Wilson, E.O. 1993. The Biophilia Hypothesis. Island Press, Washington, DC. 484 pp.
Donovan, G.H., Butry, D.T., 2009. The value of shade: estimating the effect of urban trees on
summertime electricity use. Energy Build. 41, 662–668.
Wolch, J. et al 2005. Parks and Park Funding in Los Angeles: An Equity-Mapping Analysis, Urban
Geography, 26:1, 4-35.
Richards, N. A. 1983. “Diversity and Stability in a Street Tree Population.” Urban Ecology 7(2):159–
171.
Richards, N.A. 1993. Reasonable guidelines for street tree diversity. Journal of Arboriculture
19:344–349.
Swiecki, T.J., and Bernhardt, E.A. 2001. Guidelines for Developing and Evaluating Tree
Ordinances.
Miller, R. W., Hauer, R. J., & Werner, L. P. (2015). Urban Forestry: Planning and Managing Urban
Greenspaces, Third Edition.
Hauer R. J. and Peterson W. D. 2014. Municipal Tree Care and Management in the United States:
A 2014 Urban & Community Forestry Census of Tree Activities. Special Publication 16-1, College
of Natural Resources, University of Wisconsin – Stevens Point. 71 pp.
Nowak, D.J., Greenfield, E.J. 2018. Declining urban and community tree cover in the United
States. Urban Forestry & Greening 32 (2018) 32-55.
Kempter, G.P. 2004. Best Management Practices – Utility Pruning of Trees. International Society
of Arboriculture.
Campbell, W.C. 2019. Western Kentucky University Stormwater Utility Survey.
Clark, J.M., Matheny, N.P., Cross, G., Wake, V. 1997. A Model of Urban Forest Sustainability. Journal
of Arboriculture 23(1). 14 pp.
2018 Urban Tree Canopy Assessment, PlanIT Geo and the City of Renton, WA. 40 pp.
2021 Urban Forest Inventory & Resource Analysis Summary Report, Davey Resource Group and
the City of Renton, WA. 72 pp.
RENTON, WA
URBAN FOREST
MANAGEMENT PLAN
10-YEAR UPDATE
JANUARY 2022