HomeMy WebLinkAboutL2STA DRAFT VegWildDR SegA 2015-04-14Lake to Sound Trail—Segment A
Vegetation and Wildlife Discipline Report
Prepared for
King County
Parks Division
201 South Jackson, Seventh Floor
Seattle, WA 98104
Prepared by
Parametrix
719 2nd Avenue, Suite 200
Seattle, WA 98104
T. 206.394.3700 F. 1.855.542.6353
www.parametrix.com
CITATION
Parametrix. 2015. Lake to Sound Trail—Segment A
Vegetation and Wildlife Discipline Report. Prepared by Parametrix, Seattle, Washington. April 2015.
TABLE OF CONTENTS
1. INTRODUCTION 1-1
1.1 PROJECT OVERVIEW 1-1
1.2 PROJECT FEATURES 1-1
1.3 PROJECT AREA AND SETTING 1-5
1.4 PROJECT PURPOSE AND NEED 1-6
2. METHODOLOGY 2-1
2.1 METHODS OF ANALYSIS 2-1
2.2 STUDIES AND COORDINATION 2-1
2.2.1 Review of Existing Information 2-1
2.2.2 Field Investigation 2-2
2.2.3 Regulations 2-5
3. AFFECTED ENVIRONMENT 3-1
3.1 STUDY AREA 3-1
3.2 LAND COVER TYPES IN THE STUDY AREA 3-1
3.2.1 Riparian-Wetland 3-2
3.2.2 Herbaceous Wetland 3-5
3.2.3 Urban 3-5
3.2.4 Open Water 3-5
3.3 WILDLIFE SPECIES IN THE STUDY AREA 3-6
3.4 SPECIAL-STATUS SPECIES IN THE STUDY AREA 3-6
3.4.1 Bald Eagle 3-8
3.4.2 Great Blue Heron 3-9
3.4.3 Western Toad 3-12
3.4.4 Peregrine Falcon 3-12
3.4.5 Pileated Woodpecker 3-12
3.4.6 Townsend’s Big-eared Bat 3-12
4. ENVIRONMENTAL CONSEQUENCES 4-1
4.1 CONSTRUCTION EFFECTS 4-1
4.1.1 Vegetation 4-1
4.1.2 Wildlife 4-3
4.1.3 Special-status Species 4-3
4.2 OPERATIONAL EFFECTS 4-10
5. MITIGATION 5-1
5.1 AVOIDANCE AND MINIMIZATION MEASURES 5-1
5.2 RESTORATION OF TEMPORARY EFFECTS 5-2
5.3 COMPENSATORY MITIGATION 5-2
6. REFERENCES 6-1
LIST OF FIGURES
1-1 Vicinity Map 1-3
2-1 Mapped Sensitive Areas and Habitat 2-3
3 1 Vegetation and Wildlife Study Area Base Map 3-3
4-1 Year-round and Seasonal Buffers for the Black River Heron Nesting Colony 4-7
LIST OF TABLES
3 1 Land Cover in the Wildlife and Vegetation Study Area for the Lake to Sound Trail—Segment A Construction Project 3-2
3 2 Special-status Species Documented or Expected to Occur in the Study Area 3-8
APPENDICES
A Bird Species Likely to Occur in the Lake to Sound Trail—Segment A Study Area
ACRONYMS
AASHTO American Association of State Highway and Transportation Officials
BNSF Burlington Northern Santa Fe
ESA Endangered Species Act
FHWA Federal Highway Administration
GIS geographic information system
NEPA National Environmental Policy Act
NHP Natural Heritage Program
PHS Priority Habitats and Species
RMC Renton Municipal Code
TMC Tukwila Municipal Code
USFWS U.S. Fish and Wildlife Service
WDFW Washington Department of Fish and Wildlife
WDNR Washington Department of Natural Resources
WSDOT Washington State Department of Transportation
INTRODUCTION
This discipline report is intended to provide information in support of the Washington State Department of Transportation (WSDOT) Environmental Classification Summary form for the National
Environmental Policy Act (NEPA) Documented Categorical Exclusion process, assist project planning, and facilitate permitting. This report describes vegetation and wildlife resources
in the area of a proposed 1.2-mile non motorized trail, evaluates potential impacts to critical areas from the proposed project, and presents mitigation for these impacts.
Project Overview
King County, together with the Cities of Renton and Tukwila, WSDOT, and the Federal Highway Administration (FHWA), is proposing to develop a 1.2-mile-long segment of what will ultimately
be the 16-mile Lake to Sound Trail. The 1.2-mile-long segment is referred to as Segment A of the Lake to Sound Trail. Segment A extends from Naches Avenue SW, runs parallel to the railroad
tracks north of the Black River Riparian Forest, across a proposed non-motorized pedestrian bridge northeast of Monster Road, and under two railroad bridges to the Green River Trail
at the north end of the Starfire Sports Complex in Fort Dent Park (Figure 1-1).
Segment A, as well as the longer Lake to Sound Trail, is part of a Regional Trail System that provides non-motorized, alternative transportation and a recreational corridor for multiple
trail users, including bicyclists, pedestrians, skaters, and others. A goal of the Lake to Sound Trail is to provide non-motorized transportation facilities to economically disadvantaged
communities in southwest King County that have been historically underserved by such facilities.
Once complete, Segment A would become part of a larger planned system that would serve employment and residential centers in South King County and connect to regional trails in Seattle
and the greater Regional Trail System network. Segment A would provide a much-needed trail connection between the regional growth centers of Renton and Tukwila and safe passage under
the heavy rail lines. In addition to the Green River Trail, Segment A would connect to the Interurban Trail to the south, and in the future to the Cedar River Trail.
Project Features
Segment A is typically approximately 12 feet of asphalt pavement bounded by two 2-foot-wide shoulders and 1-foot-wide clear zones, in accordance with American Association of State Highway
and Transportation Officials’ (AASHTO) guidelines. The project includes:
Constructing a 12-foot-wide asphalt pavement trail with soft-surface (gravel) shoulders
Performing minor grading to construct the trail (approximately 1,410 cubic yards of cut and 2,980 cubic yards of fill, disturbing an area of approximately 0.7 acre outside the proposed
trail footprint)
Performing ground improvements, which would disturb an area of approximately 0.17 acre in addition to other disturbances from the trail
Constructing a new non-motorized pedestrian bridge, including abutments, over the Black River northeast of Monster Road (the existing Monster Road bridge cannot be improved to safely
accommodate the envisioned trail)
Installing a pedestrian-actuated signal crossing of Monster Road south of the bridge
Figure 1-1. Vicinity Map
Constructing an undercrossing feature beneath two railroad bridges to protect trail users from potential falling debris
Installing one box culvert for terrestrial habitat enhancement
Building retaining walls near the south approach to Monster Road, north of the proposed pedestrian bridge over the Black River, and on either side of the box culvert
Constructing two approximately 10-foot by 20-foot pull-out rest areas (one at the northern perimeter of the Black River Riparian Forest and one east of Monster Road and northwest of
the Black River pump station)
Installing split-rail fencing and plantings to discourage incursions into sensitive areas and to improve visual screening for sensitive wildlife
Measures that would be implemented to avoid or minimize the potential for adverse effects on vegetation and wildlife resources are identified in Section 5.1 of this report.
Project Area and Setting
The Segment A project area is a linear corridor mostly within an existing trail corridor (see Figure 1-1). Segment A is located in Section 13, Township 23 North, Range 4 East, Willamette
Meridian. Two parallel railroad tracks (Burlington Northern Santa Fe [BNSF] and Union Pacific) cross the western quarter of the proposed trail corridor on elevated bridges heading north-south.
Another set of BNSF railroad tracks are located north of the eastern three-quarters of the proposed trail corridor with an east-west bearing. These tracks tie into the north-south tracks
north of the project area. East of the railroad bridges, the proposed trail alignment is within the City of Renton; west of the railroad bridges, the proposed trail alignment is within
the City of Tukwila. The project area is described from east to west below.
The east terminus is located at a cul-de-sac on Naches Avenue SW near an office park. The eastern three-quarters of the proposed trail alignment from Naches Avenue SW to the proposed
pedestrian bridge northeast of Monster Road (approximately 4,100 linear feet) follows an existing gravel maintenance road south of the BNSF east-west railroad tracks and north of the
Black River, along the northern perimeter of the Black River Riparian Forest (see Section 3.3 of this report for a more detailed description of the Black River Riparian Forest and the
wildlife communities it supports). The gravel maintenance road is currently used for walking and pet exercise. The existing road surface in most of this portion consists of compacted
gravel and ranges from 10 to 12 feet wide. Areas immediately outside the edge of the existing gravel surface generally consist of grasses, low-growing annual plants, blackberry thickets,
and native riparian trees. Uses outside this portion of the project area include a concrete recycling plant and an area zoned for light industrial uses just north of the railroad tracks.
The proposed trail alignment crosses over the Black River using a new non-motorized pedestrian bridge northeast of Monster Road Bridge, then crosses Monster Road south of the river.
For the western quarter of the proposed trail alignment, west of Monster Road, the alignment lies south of the Black River. For the first 150 feet west of Monster Road, the alignment
is on existing paved surfaces, and then it follows a dirt footpath that joins an existing dirt road beneath the railroad bridges for 650 feet. The westernmost 600 feet of the proposed
trail alignment is on maintained lawns associated with Fort Dent Park. West of the railroad bridges, the area south of the proposed trail alignment is dominated by Fort Dent Park and
the Starfire Sports Complex. The confluence of the Black and Green Rivers is located just
north of the west end of the Segment A project area. Commercial businesses are north of the Black River and south of the trail corridor.
Project Purpose and Need
The purpose of the Segment A project is to design and construct an alternative non motorized transportation corridor and multi-use recreational trail between Naches Avenue SW in Renton
and the Green River Trail in Tukwila. Segment A would provide non-motorized access to recreation and employment centers and would complete a link in the Regional Trail System network.
The trail is intended to safely accommodate a variety of groups such as bicyclists, pedestrians, runners, wheelchair users, and skaters. Trail design standards would safely accommodate
different ages and skill levels within those groups.
Completion of Segment A would provide the following benefits:
Serve local and regional non-motorized transportation needs and provide access to the trail for local communities.
Help satisfy the regional need for recreational trails and provide safe recreational opportunities to a wide variety of trail users.
Provide a critical link in the Regional Trail System.
Provide economic and health benefits to communities along the trail.
METHODOLOGY
This study is based on a review of existing information and field investigations. The goal of these efforts is to document existing information, to reflect current site conditions, and
to collect new information to assess potential impacts.
Methods of Analysis
To establish the basis for the analysis of effects on vegetation and wildlife, the ecosystems analysts delineated and classified land cover types on a 2009 aerial photograph and visited
a sample of these areas during field reconnaissance surveys. The analysts identified land cover types in the vegetation and wildlife study area (see Section 3.1 for a discussion of
how the study area was defined), based on the structural categories defined in Wildlife-Habitat Relationships in Oregon and Washington (Johnson and O’Neil 2001). These land cover types
are described in Section 3.2, Vegetation Types in the Study Area. Within 100 feet of the project footprint, wetland identification was based on field delineations conducted in support
of the Critical Area Study (Parametrix 2015a). In areas where no field delineations were conducted, wetland identification was based on available geographic information system (GIS)
data, supplemented by aerial photograph interpretation.
To support the analysis of effects on wildlife, the ecosystems analysts identified wildlife species that are associated with the land cover types in the study area, and with specific
habitat elements within each cover type. Analysts also assessed locations of known ecologically sensitive areas and important wildlife occurrences that may be sensitive to disturbance
from noise or human presence. This information was supplemented with data gathered during field reconnaissance visits.
The analysts evaluated the potential effects of the proposed action on vegetation and wildlife using a variety of methods and resources, including the following:
GIS analysis to determine the acreage, type, and location of affected cover types
Review of existing literature on the effects of trail construction, use, and maintenance on vegetation and wildlife
Review of Washington Department of Fish and Wildlife (WDFW) management recommendations for priority habitats and species
Biologists reviewed information provided by project engineers and identified aspects of the project that could alter habitat conditions or disturb wildlife in the project vicinity.
Studies and Coordination
The ecosystems analysts used a combination of existing information and field surveys to gain an understanding of vegetation and wildlife resources that may be affected by the development
of Segment A. These information sources, as well as the regulations that drive the need for this analysis, are identified below.
Review of Existing Information
To identify and classify existing vegetation types, and to estimate wildlife occurrence in the project study area, the analysts reviewed the following sources:
U.S. Fish and Wildlife Service (USFWS) online Information, Planning, and Conservation System (USFWS 2015a)
Washington Department of Natural Resources (WDNR) Natural Heritage Program (NHP) database (WDNR 2014)
WDFW Priority Habitats and Species (PHS) database (WDFW 2015)
Aerial photographs (2009)
Peer-reviewed and unpublished literature
Interviews with staff at federal, state, local agencies, and local interest groups
Information collected during a field reconnaissance of the study area
The analysts reviewed the USFWS list of threatened, endangered, proposed, and candidate species to determine which species with ESA status have the potential to occur in the study area.
Analysts reviewed NHP data for known locations of rare plant species or rare plant communities within the study area, and PHS data for known locations of wildlife species that are a
management concern for WDFW, as well as habitats with unique or significant value. Figure 2-1 displays the location of the proposed trail alignment relative to mapped sensitive areas
and habitat. Note that the locations of sensitive areas and habitat depicted in Figure 2 1 are approximate and subject to change. For example, great blue heron nests may be concentrated
in the area identified as the heron colony in the figure but they may not be limited to that area.
Field Investigation
Biologists conducted a limited field reconnaissance to verify habitat mapping and to observe wildlife species in the vicinity of the proposed trail alignment. A wildlife biologist conducted
a site visit on March 29, 2011. Biologists conducting site visits for the wetlands and stream discipline reports also collected data about wildlife use of the area between November
2010 and February 2011. In accordance with WDFW’s management recommendations for the great blue heron (Azerrad 2012), biologists also searched the Black River Riparian Forest for
evidence of heron nests, including satellite nests (i.e., nests in outlying areas away from the greatest concentration of nests). In a single-day visit during the non-breeding season
(January 10, 2013), biologists used global positioning system equipment to map the locations of all trees with heron nests, as well as trees with canopies overlapping a nest tree, confirming
nest locations with aerial imagery.
No formal surveys were conducted for any other wildlife species. If the project site falls within the known or expected range of a particular species, and if habitat for that species
is present within the study area, then the species is assumed to be present.
Figure 2-1. Mapped Sensitive Areas and Habitat
Regulations
The following federal regulations or statutes apply to the protection of vegetation and wildlife in the study area:
Endangered Species Act
Bald and Golden Eagle Protection Act
Migratory Bird Treaty Act
Clean Water Act Sections 401 and 404
State and local regulations that apply to these resources include the Shoreline Management Act, Growth Management Act, and sensitive/critical area ordinances for the Cities of Renton
and Tukwila. The general goal of these regulations is to protect water quality, shorelines, aquatic habitat, wetlands, riparian areas, and associated terrestrial habitats, as well as
the species that depend on these areas.
The City of Renton Municipal Code (RMC) outlines requirements for the protection of wildlife and wildlife habitat in section 4-3-050, Critical Areas Regulations, subsection K, Habitat
Conservation. Critical habitats include Category 1 wetlands (see the Critical Area Study [Parametrix 2015a] for a definition), as well as habitats associated with the documented presence
of species proposed for listing or listed by the federal government or WDFW as endangered, threatened, or candidate species. State sensitive, monitor, and priority species also receive
consideration under the Critical Areas Regulations. In addition, the entire area of the Black River Riparian Forest is managed under the City of Renton’s Shoreline Master Program, which
requires shoreline areas to be managed for no net loss of ecological functions (e.g., fish and wildlife habitat, food chain support, water temperature maintenance) or process (e.g.,
water flow; erosion and accretion; infiltration; groundwater recharge and discharge; sediment delivery, transport, and storage; large woody debris recruitment; organic matter input;
nutrient and pathogen removal; stream channel formation/maintenance). The City of Tukwila Municipal Code (TMC), Chapter 18.54.030, sets forth rules and regulations to control the clearing
of trees and understory vegetation within sensitive areas and shoreline zones in the City of Tukwila. The portion of Segment A that passes through Fort Dent Park is in the City of Tukwila;
areas within 200 feet of the Green River are in the shoreline zone. Conservation of fish and wildlife is regulated through TMC 18.44, Shoreline Overlay District, as well as the regulations
related to wetlands and watercourses in TMC Chapter 18.45.
In addition to the regulatory and statutory requirements identified above, WDFW has developed management recommendations for priority species and habitats. The purpose of these recommendations
is to assist landowners, managers, and others in conducting land use activities in a manner that incorporates the needs of fish and wildlife (WDFW 2008). Pertinent to the analyses in
this document are WDFW’s management recommendations for the great blue heron (Azerrad 2012). Several individuals and organizations have expressed particular concern about the potential
effects of trail construction and use on this species. Information from these management recommendations is incorporated into the discussions of affected environment and environmental
consequences for great blue herons below.
AFFECTED ENVIRONMENT
This section describes the vegetation and wildlife resources in the vicinity of the Lake to Sound Trail—Segment A project. The following subsections describe the project setting, define
the study area within which effects are analyzed, identify plant communities and habitat types in the study area, and identify wildlife species (including special-status species) that
are known or have the potential to occur in the study area.
Study Area
Analysts defined the study area for vegetation and wildlife as the project alignment (i.e., the area in which clearing, grading, and the operation of construction machinery would disturb
existing habitat) plus all areas within 300 feet. This is the area in which project construction could affect vegetation cover and habitat quality for wildlife species that may occur
in the area. Such effects could include direct modifications to habitat or indirect effects through modification of habitat in adjoining areas. In addition to evaluating habitat conditions
within this study area, biologists assessed the potential for project-related noise and human activity to disturb sensitive wildlife species up to 1,300 feet from the proposed trail
alignment. This distance was based on published guidelines for avoiding disturbance to sensitive species that may occur in the project vicinity (USFWS 2007; Azerrad 2012).
Segment A is within the western hemlock (Tsuga heterophylla) forest zone, which extends from Puget Sound into the foothills of the Cascade Mountains (Franklin and Dyrness 1988). Principal
forest species in this zone are western hemlock, Douglas-fir (Pseudotsuga menziesii), and western redcedar (Thuja plicata). Hardwoods, including bigleaf maple (Acer macrophyllum), red
alder (Alnus rubra), and black cottonwood (Populus balsamifera var. trichocarpa), are less common and found primarily on disturbed sites and riparian habitats. Most native habitat in
the Puget Lowlands has been subject to a variety of human disturbances over the past 150 to 200 years, including timber harvest, conversion to agriculture, road construction, and urban
development. This has resulted in significant alteration of the original vegetation; much of the region is now dominated by urban and residential land uses.
In contrast to regional trends, much of the vegetation and wildlife study area consists of a large stand of riparian hardwood forest that has not been permanently converted to other
uses. The area south of the BNSF railroad corridor is dominated by large trees and dense thickets of shrubby wetland. The portion north of the railroad corridor, however, consists of
an active concrete recycling plant and areas that have been cleared for light industrial development, and supports essentially no vegetation. The western end of the study area extends
into Fort Dent Park in Tukwila. The remaining vegetation in this area consists of maintained lawns and horticultural plantings with scattered trees.
Land Cover Types in the Study Area
Based on the structural categories defined by Johnson and O’Neil (2001), four land cover types occur in the study area: riparian-wetland, herbaceous wetland, urban, and open water (Figure
3-1). Approximately 55 percent of the study area, including almost the entire area north of the trail alignment, consists of urban land cover (Table 3-1). Riparian-wetland areas, which
predominate south of the alignment, are the second most common cover type. Open water and herbaceous wetlands represent comparatively small proportions of the area. Note that the riparian-wetland
and herbaceous wetland land cover types are not synonymous with delineated wetlands, which are regulated under the Clean Water Act and local critical areas ordinances. Wetlands are
discussed in the Lake to Sound Trail—
Segment A Critical Area Study (Parametrix 2015a). The following subsections describe these cover types, including their structural characteristics, typical plant species, wildlife habitat
functions, and conditions in the study area.
Table 3 1. Land Cover in the Wildlife and Vegetation Study Area for the
Lake to Sound Trail—Segment A Construction Project
Land Cover Type
Acres in the Study Area a
Riparian-Wetland
33
Herbaceous Wetland
1
Urban
49
Open Water
5
Total
88
a The study area consists of all areas within 300 feet of the project alignment.
Riparian-Wetland
This habitat type typically consists of a mosaic of forest and tall shrublands. Trees are evergreen conifers or deciduous broadleaf or a mixture of both, with understories composed of
shrubs, forbs, and/or grasses. Water is sometimes present on the surface for a portion of the year. Small stream channels and small backwater channels on larger streams are included
in this habitat. Wetlands classified according the USFWS classification system (Cowardin et al. 1979) as palustrine forested and palustrine scrub-shrub are included in this habitat
type. For this analysis, this habitat type also includes unmaintained grassy areas at the periphery of the Black River Riparian Forest, as well as the vegetated banks of the Black River
and the Green River.
Typical tree species in the riparian-wetland portion of the study area include red alder, black cottonwood, Pacific willow (Salix lucida), Oregon ash (Fraxinus latifolia), and western
redcedar. Grand fir (Abies grandis) and bigleaf maple are also present within and adjacent to some wetland areas. Common shrub species include salmonberry (Rubus spectabilis) and red-osier
dogwood (Cornus sericea) in wetland areas, and Himalayan blackberry (Rubus armeniacus), red elderberry (Sambucus racemosa), and snowberry (Symphoricarpos albus) in adjacent uplands.
Beavers (Castor canadensis) play an important role in the riparian-wetland habitat type by constructing dams that change the hydrology of the stream system. The presence of Himalayan
blackberry, reed canarygrass (Phalaris arundinacea), and other exotic species within the riparian-wetland portions of the study area indicate the site has been impacted by human disturbance.
Figure 3 1. Vegetation and Wildlife Study Area Base Map
Herbaceous Wetland
In western Washington, herbaceous wetlands commonly co-occur with riparian-wetlands along stream corridors. Seasonally to semi-permanently flooded wetlands are found where standing fresh
water is present through part of the growing season and the soils stay saturated throughout the season. The herbaceous wetland habitat is generally a mix of emergent herbaceous plants
with a grass-like life form (graminoids). These meadow-like areas often occur with deep- or shallow-water habitats with floating or rooting aquatic forbs.
Species identified in herbaceous wetlands in the study area include reed canarygrass and narrow-leaf cattail (Typha angustifolia).
Urban
Urban development occupies much of the lowland area of western Washington. Most original habitat has been dramatically altered in urban environments and is replaced by buildings, impermeable
surfaces, bridges, dams, and plantings of non-native species. Some human-made structures provide habitats similar to those of cavities, caves, fissures, cliffs, and ledges. Urban areas
typically have high levels of human disturbance. Ground cover in the most intensively developed areas, if not synthetic or impervious, is typically exotic grasses or annuals, most of
which are rarely allowed to go to seed. Vegetation in residential areas typically consists of manicured lawns, trimmed hedges, and pruned trees. Snags, woody debris, and other natural
structures are essentially nonexistent (Johnson and O’Neil 2001).
Urban cover types in the vegetation and wildlife study area include the concrete recycling plant and neighboring areas that have been cleared for light industrial development. Most of
the northern portion of the study area consists of urban land cover. Other areas mapped as urban cover include roadways, disturbed openings, most of the existing trail corridor, buildings
and parking lots, and maintained areas within Fort Dent Park. Riparian vegetation in the urban portions of the study area is sparse, with only a few scattered deciduous trees. Shrub
vegetation is dominant, including a large amount of Himalayan blackberry. The vegetation is not adequate to provide for the functions of a properly functioning riparian zone (i.e.,
stream shading, large woody debris recruitment, leaf litter input, etc.). Levels of noise and human activity in urban areas are typically higher than in less developed settings. During
site visits conducted for this report, noise from heavy machinery in the concrete recycling business was audible along the portions of the trail corridor that are mapped as urban land
cover.
Some portions of Fort Dent Park that are mapped as urban land cover currently support trees ranging from saplings to mature specimens. These include a row of 16 Douglas-fir trees north
of the sports fields, ranging in size from 12 to 20 inches in diameter at breast height. Several smaller deciduous trees occur in the vicinity of the proposed trail alignment in this
area.
Open Water
Throughout the Puget Sound region, ponds and lakes are often found in the same areas as herbaceous wetlands, while rivers and streams typically adjoin riparian-wetland areas. Many ponds
and marshes have been created or are maintained by the activity of beavers. Human-made reservoirs created by dams impound water that creates lake-like habitat. Most of the streams entering
Puget Sound originate in glacier fields high in the mountains. Water from melting snowpacks and glaciers provides flow during the spring and summer. Open water habitat in the study
area includes the lagoon above the Black River
pump station, and short stretches of the Black River, Green River, and Duwamish River. Open water habitat provides foraging areas for bald eagles, osprey, and great blue herons, and
breeding habitat for several species of amphibians, such as northwestern salamanders, long-toed salamanders, and Pacific chorus frogs.
Wildlife Species in the Study Area
Much of the land in the southern half of the study area is natural open space, primarily forested riparian and wetland habitat. This is the Black River Riparian Forest, which supports
a diverse wildlife community, including bald eagles and a colony of great blue herons that has actively nested here every year since 1986 and has been one of the largest such colonies
in the Puget Sound region (Stenberg 2007). Data from the WDFW PHS program indicate that the Black River Riparian Forest is also used by many waterfowl species, including bufflehead,
mallard, gadwall, wigeon, scaup, and green-winged teal (WDFW 2015). Other bird species commonly found in riparian and wetland habitats in the Puget Lowlands include osprey, red-tailed
hawk, and a variety of songbirds (Appendix A). Mammals present may include coyotes, raccoons, beavers, mice, voles, and moles. Reptiles and amphibians that use these habitats include
garter snakes, Pacific chorus frogs, and long-toed salamanders.
Based on breeding bird survey reports (Opperman et al. 2006), 52 bird species are known or expected to nest in the nine-square-mile survey block that contains the project area; an additional
20 species are known or expected to nest in adjacent survey blocks (Appendix A). Based on Christmas Bird Count data rom the Audubon Society (2011), common winter visitors to the area
include northern pintails, western grebes, and glaucous-winged gulls.
Rivers and streams are used as travel corridors by many wildlife species, including semi-aquatic species such as muskrat, mink, otter, frogs, stream salamanders, turtles, and snakes
(Jackson 2003). Despite the widespread urbanization of the Green River corridor, riparian areas along the river may serve as a connective corridor between Puget Sound and undeveloped
areas in the Cascade Mountains. No corridors that have been identified as part of the wildlife habitat network in the King County Comprehensive Plan are present within or adjacent to
the study area, however.
Special-status Species in the Study Area
Special-status species include (1) species listed as endangered or threatened under the ESA, (2) species that are candidates or proposed for listing under the ESA, (3) species listed
by WDFW as endangered, threatened, candidate, or sensitive, and (4) other species for which critical habitat areas are designated by the City of Renton or for which fish and wildlife
habitat conservation areas are designated by the City of Tukwila.
As defined in the RMC, critical habitats are Category 1 wetlands and habitat associated with the documented presence of species proposed or listed by the federal government or the State
of Washington as endangered, threatened, candidate, sensitive, monitor, or priority. Areas designated as fish and wildlife habitat conservation areas by the City of Tukwila are mapped
by the City; they include areas with which endangered, threatened, or sensitive species have a primary association, as well as habitats and species of local importance.
Information from the Washington Department of Natural Resources (WDNR) Natural Heritage database indicates that no threatened or endangered plants are known to occur within 5 miles of
the study area (WDNR 2014). The only ESA-listed plant with the potential to occur in King County is golden paintbrush
(Castilleja levisecta), which is known from historical observations in the region. Suitable habitat for golden paintbrush (open grasslands in glacial outwash prairies) is not present
in the study area.
There are no known occurrences of special -status plant species within 5 miles of the study area (WDNR 2014). There are no extant occurrences of ESA-listed plant species in King County
(USFWS 2015a).
In addition to being protected through various regulatory mechanisms, many plants and lichens have traditionally been used by a wide variety of cultures in western Washington. Traditional
uses include food, medicine, fibers, textiles, building materials, and spiritual uses. Botanical specialists reviewed a list of 84 species of trees, shrubs, herbs, ferns, and lichens
identified by WSDOT as ethnobotanical resources in western Washington (WSDOT 2010) and determined that many of these species are present in the study area.
The USFWS Information, Planning, and Conservation System identified seven ESA-listed wildlife species as potentially occurring in areas that might be affected by the proposed project.
None of these species is expected to occur in the study area, however, for the following reasons:
Canada lynx (Lynx canadensis), grizzly bear (Ursus arctos horribilis), and gray wolf (Canis lupus) are identified as potentially occurring in King County. However, the study area is
in a lowland setting with relatively high levels of human activity and no nearby roadless areas and thus does not provide suitable habitat for any of these species. No observations
of any of these species have been documented within 5 miles of the study area (WDFW 2015).
Oregon spotted frogs (Rana pretiosa) occur in Washington State at large wetland complexes in Klickitat, Skamania, Thurston, Skagit, and Whatcom counties. Oregon spotted frogs depend
on relatively large areas with perennial bodies of fresh water and associated wetlands. No observations of this species have been documented within 10 miles of the study area (WDFW
2015). The nearest location where critical habitat has been proposed for the Oregon spotted frog is more than 40 miles from the study area (USFWS 2015b).
Marbled murrelets (Brachyramphus marmoratus) require old-growth forest for nesting and marine habitat for foraging. No breeding or foraging habitat is present in the study area and no
observations have been documented within 5 miles (WDFW 2015). The nearest location where critical habitat has been designated for the marbled murrelet is more than 25 miles from the
study area.
Yellow-billed cuckoos (Coccyzus americanus) require large blocks of riparian forest habitat for breeding and foraging. No such habitat is present in or near the study area. Currently,
the species no longer breeds in western Canada and the northwestern continental United States (Washington, Oregon, and Montana) (79 FR 59992, October 3, 2014). No observations of this
species have been documented within 10 miles of the study area (WDFW 2015). No critical habitat for the yellow-billed cuckoo has been proposed in Washington State.
Streaked horned larks (Eremophila alpestris strigata) are known to occur in Washington State only in portions of southern Puget Sound, along the Washington coast, and at lower Columbia
River islands (78 FR 61452, October 3, 2013). Breeding habitat for streaked horned larks in Washington consists of grasslands and sparsely vegetated areas at airports, sandy islands,
and coastal spits. The subspecies is largely absent from the Puget Trough during the nonbreeding season; individuals observed in this area outside of the breeding season have been seen
using habitats similar to those used for breeding. No such habitat is present in the study area, and the study area is not within the known range of the subspecies. The nearest location
where critical
habitat has been designated for the streaked horned lark is more than 90 miles from the study area.
Based on the above, the proposed project has no potential to affect Canada lynx, grizzly bears, gray wolves, Oregon spotted frogs, marbled murrelets, yellow-billed cuckoos, or streaked
horned larks. These species will not be addressed further in this analysis.
The Migratory Bird Treaty Act, administered by USFWS, makes it unlawful to take, import, export, possess, sell, purchase, or barter any migratory bird, with the exception of the taking
of game birds during established hunting seasons. The law also applies to feathers, eggs, nests, and products made from migratory birds. Nearly all bird species that may occur in the
study area are protected under the Migratory Bird Treaty Act. All habitats in the study area support migratory birds of some type at some time in their life cycle, therefore all habitats
identified above would be considered habitat for migratory birds.
Table 3-2 lists special-status wildlife species that have been observed or that may occur in the study area. Documented species include those for which occurrences have been recorded
in the WDFW PHS database or that have been observed during field reconnaissance visits. Analysts determined the potential for other special-status species to occur in the study area
based on the species’ ranges, as well as the presence in the study area of habitat commonly used by the species. Species that could potentially be affected by construction or use of
the trail are discussed below.
Table 3 2. Special-status Species Documented or Expected to Occur in the Study Area
Species
Status
Occurrence in Study Area
Bald eagle
(Haliaeetus leucocephalus)
State sensitive
Documented
Great blue heron (Ardea herodias)
State monitor
Documented
Western toad (Bufo boreas)
State candidate
Not documented; may occur
Peregrine falcon (Falco peregrinus)
State sensitive
Not documented; may occur
Pileated woodpecker (Dryocopus pileatus)
State candidate
Documented
Townsend's big-eared bat
(Corynorhinus townsendii)
State candidate
Not documented; may occur
Bald Eagle
Bald eagles receive protection under the federal Bald and Golden Eagle Protection Act (16 USC 668-668d), which prohibits take (defined to include pursuing, shooting, poisoning, wounding,
killing, capturing, trapping, collecting, molesting, or disturbing bald or golden eagles), possession, and commerce of these species. Proposals for commercial or residential development
within 660 feet of bald eagle nests, roost sites, or foraging areas may be required to comply with federal guidelines for bald eagle management.
Bald eagles use large trees for nesting, roosting, and perching. In Washington, nearly all bald eagle nests are within 1 mile of a lake, river, or marine shoreline (Stinson et al. 2001).
Bald eagles typically forage over open water and use riparian trees (often cottonwood) for perching.
During the breeding season, bald eagles are sensitive to a variety of human activities. However, not all bald eagle pairs react to human activities in the same way. Some pairs nest successfully
just dozens of yards from human activity, while others abandon nest sites in response to activities much farther away. In general, the bald eagle breeding season in Washington State
extends from January 1 through August 31 (Watson and Rodrick 2004). Eagles are most sensitive to disturbance between early February and early May, when they are establishing territories,
incubating eggs, and tending newly hatched chicks. Another period of heightened sensitivity occurs in early July, when the young may be frightened off the nest before they are able
to fly (USFWS 2007).
PHS data show one bald eagle nest site within 1,000 feet of the project area (WDFW 2015). The branch that supported this nest blew down and eagles did not nest at that location in 2010.
In 2011, biologists and other visitors to the Black River Riparian Forest observed no evidence of eagles nesting in the area. Another nest, on the hillslope above the concrete recycling
property, is considered by WDFW to belong to the same nesting territory. This surmise is supported by monitoring data from 2005 through 2008, showing that when one of the two nests
was active, the other was unoccupied. Such a pattern of activity is consistent with a pair of birds using alternating sites in a single nesting territory. The nest site above the concrete
recycling property is approximately 1,300 feet away from the proposed trail alignment.
Before 2010, eagles from the Black River nesting territory were observed preying on great blue herons in the Black River nesting colony. During the March 2011 site visit, an adult bald
eagle was observed flying low over the site of the heron colony. The Green River likely also provides foraging habitat for bald eagles in the area.
Great Blue Heron
Great blue herons are associated with wetlands, seashores, rivers, swamps, marshes, and ditches (Quinn and Milner 2004). The availability of nesting, foraging, and pre-nesting areas
close to one another is a key factor in determining the suitability of habitat for great blue herons (Gebauer and Moul 2001). Nesting typically occurs in colonies of a few pairs to
many hundreds of birds; occasionally, great blue herons nest as isolated pairs (Butler 1997). Ideal nesting habitat typically consists of mature forest (Gebauer and Moul 2001), although
herons nest occasionally on the ground, in shrubs, on cliffs, or on human-made structures (Azerrad 2012). During the breeding season, herons forage primarily in the shallow margins
of waterbodies within approximately 2 miles of a nesting colony (Butler 1997). Pre-nesting congregation areas have been documented near many nesting colonies. Great blue herons gather
at these sites at or before the beginning of the breeding season (Azerrad 2012).
Although not a state-listed or ESA-listed species in Washington, the great blue heron is a species of special concern in British Columbia due to declining productivity (COSEWIC 2008).
Great blue herons are highly vulnerable to predation, human disturbance, and competition for nesting habitat (COSEWIC 2008; Azerrad 2012). The study area falls within the range of the
Pacific subspecies (Ardea herodias fannini), which is found in coastal areas and along large rivers from Prince William Sound to Puget Sound (Azerrad 2012).
Nesting colony locations are dynamic, especially in areas of high disturbance. Some colonies are used for many years but most—especially those with fewer than 25 nests—are relocated
every few years (Gebauer and Moul 2001). Great blue herons may abandon or relocate their colonies in response to predation, declines in food availability, or increased human disturbance
(Quinn and Milner 2004; COSEWIC 2008). Kenyon (2005) found that great blue herons may respond to repeated bald eagle attacks on nesting colonies by redistributing into smaller, more
widely scattered colonies. Colony
abandonment has also resulted from activities such as nearby land development and repeated human intrusions into nesting areas (Azerrad 2012).
Even in cases where flushing or other obvious responses do not occur, human disturbance may result in reduced nesting productivity (Vennesland and Butler 2004). Human disturbance has
been identified as one of the major factors (along with predation by eagles and habitat declines from land development) limiting the persistence of heron populations in British Columbia
(COSEWIC 2008). Human disturbance may also increase the susceptibility of heron colonies to eagle predation. Reduction of forest cover may allow easier access to nest sites. In addition,
if adults are flushed from their nests, eggs and nestlings are vulnerable to predation (COSEWIC 2008).
Heron colonies vary in their sensitivity to human activities. In some instances, a single event involving human disturbance has led an entire colony to terminate a nesting attempt (Azerrad
2012). In contrast, herons nesting in public parks in Vancouver and Victoria, British Columbia, appear to tolerate the frequent presence of pedestrians and vehicles directly below their
nests (COSEWIC 2008). More sensitive colonies may respond to disturbances at a great distance. Azerrad (2012) reports that the presence of people as far as 820 feet from some heron
colonies may cause birds to flush. Herons may tolerate everyday human activities, but birds often suspend nesting when they perceive the activity to be a threat (Vennesland 2000; City
of Vancouver Parks and Recreation 2006). Vennesland (2000) found that herons habituate to non-threatening human disturbance, but that they are more sensitive to disturbance at certain
times of year. Great blue herons are less tolerant of disturbance during the pre-courtship and courtship periods (typically mid-February through mid-April in Washington), then become
less likely to flush or abandon nests once eggs have been laid (Azerrad 2012). If dense vegetation obscures human activity, herons may be less likely to react to human disturbance (Gebauer
and Moul 2001). Notably, the pre-courtship and courtship periods typically occur before deciduous trees fully leaf out in this region, increasing the vulnerability of herons to visual
and auditory disturbance during these periods.
WDFW’s management recommendations for great blue herons specify buffers to protect colonies by keeping potentially harmful activities away from nesting colonies (Azerrad 2012). In suburban
and rural areas, WDFW recommends a year-round buffer of 656 feet (200 meters) around nesting colonies. Grading, construction, and vegetation clearing are discouraged within this buffer
(Azerrad 2012). WDFW’s management recommendations also advise that trails should be directed away from the buffer area or be closed off to access in the breeding season (Azerrad 2012).
In situations where it is not feasible to implement such restrictions, WDFW offers the following recommendations:
Site the project as far as possible from nests.
Provide visual screening between nests and project disturbances.
Carry out the project during the non-breeding season.
Mitigate for the project’s infringement into the buffer area (Azerrad 2012).
WDFW’s management recommendations for great blue herons also specify seasonal buffers to protect nesting birds. Within an area that extends 656 feet beyond the outer edge of the year-round
buffer, WDFW recommends that unusually loud activities (i.e., activities generating noise levels exceeding 92
decibels at the outer boundary of the nesting colony) should not be allowed from February to September (Azerrad 2012).
The remaining habitat elements specified in WDFW’s management recommendations are pre-nesting congregation areas, alternative nest sites, and foraging habitat. WDFW recommends minimal
disturbance of any areas where herons congregate before the nesting season. To protect alternative nest sites, WDFW recommends retaining several forested nesting stands of at least
10 acres within approximately 0.6 mile (1 kilometer) of an active colony. Potentially suitable alternative nest sites include former heron colony sites (provided the site was not abandoned
in response to long-term changes in habitat conditions) and other stands with a forest structure and tree species composition similar to the active nesting stand (Azerrad 2012).
To protect foraging habitat, WDFW recommends establishing adequate riparian buffers along all bodies of water within 1.9 miles (3 kilometers) of a nesting colony. WDFW also recommends
minimizing the following activities where herons feed:
Removal of aquatic vegetation
Use of watercraft within 590 feet of shallow waters
Logging mature forest close to nearshore foraging habitat
Removing perch trees adjacent to foraging areas
Draining, filling, or dredging wetlands or marshes
Building close to riparian shorelines
For many years, the Black River Riparian Forest supported one of the largest breeding colonies of great blue herons in Washington State, with more than 100 nests distributed throughout
much of the forested area (Stenberg 2007). For much of that time, the greatest density of nests was near the eastern edge of the lagoon above the Black River pump station, near the
confluence with Springbrook Creek (Hamilton 2013 personal communication). Since 2003, nearly all nesting activity has taken place in a stand of cottonwood trees approximately 500 feet
to the northwest of that site. The approximate location of this stand is depicted in Figure 2-1. For this analysis, the actual location of the nesting stand was determined in accordance
with WDFW’s management recommendations for great blue herons (see Subsection 2.2.2, Field Investigation). The locations of nest trees or overlapping trees farthest from the center of
the colony were used to determine the perimeter of the colony. It should be noted that the locations of the nests observed during the field investigations do not define the full extent
of the area in which nesting occurred in the past, nor where future nesting attempts could occur.
In some years, herons have been observed in great numbers early in the breeding season, perched in trees along the north side of the pump station lagoon (Hamilton 2013 personal communication).
Forest stands between the pump station and the current nesting area are likely a pre-nesting congregation area for the colony. Potential foraging habitat is available within 1.9 miles
of the nesting colony along the Black, Green, Duwamish, and Lower Cedar Rivers, at various wetland mitigation sites in Renton and Tukwila, and at ponds in Waterworks Garden Park, Longacres
Business Park, Fort Dent Park, Foster Golf Course, and near Southcenter Mall.
Nesting activity at the Black River nesting colony was greatly reduced during the 2010 breeding season, likely due to predatory pressure from bald eagles (Anderson 2011 personal communication).
Several active nests, perhaps as many as six, were observed in the colony stand in 2011 and 2012, and herons continue to forage in the area. It is possible that herons will resume nesting
at this site in densities
similar to those observed in the past. Chatwin et al. (2009) described one colony, active for more than 20 years, that was abandoned in 1996 and that remained inactive until herons returned
in 2002. Local observers are continuing to monitor the Black River colony site. In January and early February 2015, as many as 25 herons were observed in and around the colony site.
By early March, however, fewer than five herons were seen and none exhibited behavior indicative of nesting, leading observers to speculate that the Black River Riparian Forest may
not support a large nesting colony in 2015. Nevertheless, the presence of relatively large numbers of herons early in the breeding season indicates the potential for continued nesting
activity at the colony site.
Western Toad
This species uses wetland habitats while in the tadpole stage and for breeding as an adult. Adult toads regularly use forested upland habitat. Western toads may occur in both wetland
habitat and riparian forest habitat in the study area.
Peregrine Falcon
Peregrine falcons typically nest in cliffs that are at least 150 feet in height, although they will also use buildings and bridges (Hays and Milner 2004). No peregrine falcon nest sites
have been documented in the study area and no suitable nesting cliffs occur within 1 mile of the project area. Falcons typically hunt in open habitats such as wetlands and croplands;
hunting territories may extend up to 15 miles from a nest site (Hays and Milner 2004). Although no peregrine falcons have been reported in the area, open habitats in the study area
may provide suitable foraging habitat for nesting or overwintering birds. The nearest known aerie is approximately 8 miles away from the project area.
Pileated Woodpecker
Pileated woodpeckers inhabit mature and old-growth forests, and second-growth forests with large snags and fallen trees. Foraging habitat includes forests containing large trees and
snags, and dead and dying wood (Lewis and Azerrad 2003). In residential and developing areas, pileated woodpeckers may occupy remnant forest patches and forage on large and small-diameter
coniferous and hardwood trees and snags (Lewis and Azerrad 2003). Trees or snags that provide suitable nesting and foraging habitat are absent from the project footprint but occur within
forested portions of the study area. Biologists delineating wetlands observed a pileated woodpecker in the project study area in 2011.
Townsend’s Big-eared Bat
The Townsend’s big-eared bat is associated with forest habitat, but is a species of concern primarily because its nursery colonies are sensitive to disturbance (Johnson and Cassidy 1997).
Nursery colonies of this species are commonly located in caves, lava tubes, or abandoned buildings; bridge abutments have occasionally been used by individual male bats as day roosts
(Woodruff and Ferguson 2005). Within the study area, the Black River pump station, the Monster Road Bridge, and the railroad bridges may provide suitable sites for day roosts. This
and other bat species may forage for insects along forest edges and over wetlands in the study area.
ENVIRONMENTAL CONSEQUENCES
The following subsections describe the potential effects of trail construction and use on vegetation and wildlife in the study area. The analysis of effects on vegetation focuses on
temporary or permanent changes in the vegetative cover in the study area. The analysis of effects on wildlife focuses primarily on the potential for trail construction or use to disturb
wildlife species, and secondarily on the potential for changes in vegetative cover to affect habitat suitability.
Construction Effects
This section describes the extent and type of temporary and permanent effects on vegetation and wildlife resources that could occur as a result of construction activities associated
with the proposed project.
Vegetation
Under the proposed action, clearing and grading for trail construction would permanently convert existing land cover within the area of the project footprint to a developed condition.
Nearly all clearing would occur along the existing maintenance road, most of which consists of hardened surfaces or non-native plants. The predominant cover type within the project
footprint is urban, consisting primarily of the gravel surface of the existing road. Approximately 1.8 acres urban land cover would be affected by trail construction. Where the trail
route falls within areas classified as riparian-wetland habitat, the project footprint is largely free of trees and shrubs that are the characteristic features of that habitat type.
Clearing for trail construction would affect approximately 0.9 acre of this land cover type and is not expected to reduce species diversity or result in a substantial reduction in plant
cover in the 88-acre study area. Some low-growing plants would be replaced with hard surfaces, however, and the overhead canopy would be reduced in some places.
Within Fort Dent Park, approximately 20 trees with trunks larger than 4 inches in diameter at breast height would be cleared for trail construction. Several others may be affected by
disturbance of understory vegetation within the areas shaded by the trees’ canopies, or through root compaction by construction activities. Because these trees are located within the
shoreline zone for the Green River, trail construction would be subject to the requirements of a Tree Clearing Permit per TMC 18.54.070. This permit would identify all affected trees,
along with the measures that would be implemented to protect them. All understory vegetation within the root zone of protected trees would either be retained or removed by methods that
do not damage the tree, then replaced with suitable vegetation, per TMC 18.54.130(1). Any tree larger than 4 inches diameter that is removed within the City of Tukwila would be replaced
with one or more new trees, based on the replacement ratios in TMC 18.54.130(3).
The City of Renton has determined that all trees within 10 feet of the paved edge of the trail should be removed, as should all cottonwood trees within 20 feet of the paved edge of the
trail, for the protection of public safety and the trail surface. In total, approximately 129 trees would be removed within the City of Renton, most of which (117) would be cottonwoods.
Only one coniferous tree (a 6-inch-diameter Douglas-fir within the clearing area for the proposed pedestrian bridge) would be removed. The other trees removed for trail construction
would be red alders (7 trees), willows (2 trees), bigleaf maple (1 tree), and native cherry (1 tree). Approximately 49 of the trees proposed for removal are between 6 inches and 10
inches in diameter. Twenty-seven trees are smaller than 6 inches, 37 trees are between 10 and 16 inches, and 16 trees (all cottonwoods) are larger than 16 inches in diameter.
Most of the trees proposed for removal in the City of Renton are within the regulatory buffers of streams and/or wetlands. As discussed in the Critical Area Study (Parametrix 2015a)
and summarized below, compensatory mitigation for the loss of trees in these areas would focus on enhancing ecological functions, ultimately providing equal or greater functions than
would be affected by the project. In addition, where the proposed trail alignment runs adjacent to the Black River Riparian Forest, all cleared trees larger than 6 inches in diameter,
whether they are inside or outside of a regulatory buffer, would be replaced by new trees at a ratio of 1:1 or greater. Planting for visual screening between the trail and the great
blue heron nesting colony (see Section 5.3, Compensatory Mitigation) could result in the planting of more trees than would be needed to meet this commitment.
Construction activities would not result in any direct effects on (i.e., fill within) wetlands or streams. Effects on the regulatory buffers around wetlands and streams would occur where
the proposed trail alignment encroaches into currently vegetated areas adjacent to these features. Trail construction would permanently affect approximately 0.49 acre of wetland buffer
and 0.60 acre of stream buffer (Parametrix 2015a, b). Approximately 0.13 acre of this area is both wetland buffer and stream buffer; therefore, the total buffer area affected would
be 0.95 acre. Note that these impacts were calculated through a different process than the GIS analysis that was used for the assessment of impacts on vegetation for this report and
therefore differ from the values presented in Table 4 1. The potentially affected wetland buffer areas are generally low-functioning and are composed primarily of grasses and forbs
along the existing maintenance road edge (Parametrix 2015a). The potentially affected stream buffer areas also generally provide minimal riparian function and are dominated by invasive
species such as Himalayan blackberry, although some native cottonwood trees would also be removed (Parametrix 2015b).
King County has developed a plan that identifies compensatory mitigation for all permanent project-related effects on wetland buffers and stream buffers. The mitigation plan, which is
described in the Critical Area Study (Parametrix 2015a) and summarized in Section 5.3 of this document, focuses on enhancing ecological functions in an area where existing buffer conditions
are degraded, ultimately providing equal or greater functions than would be affected by the project. For these reasons, trail construction is not expected to result in any net loss
of any ecological functions (e.g., fish and wildlife habitat, food chain support, water temperature maintenance) or processes (e.g., water flow; erosion and accretion; infiltration;
groundwater recharge and discharge; sediment delivery, transport, and storage; large woody debris recruitment; organic matter input; nutrient and pathogen removal; stream channel formation/maintenan
ce) in the Black River Riparian Forest.
Temporary effects on vegetation would also occur outside of the project footprint. These effects would be the result of construction equipment moving over vegetated areas, primarily
areas of grass or herbaceous vegetation. Temporary effects would likely be limited to an area within 2 feet of the project footprint. All temporarily affected areas would be restored
to pre-construction conditions and would be re-planted or seeded with native species. Vegetation in temporarily affected areas would likely return to a state resembling pre-construction
conditions within a few growing seasons after the completion of construction. Temporary impacts would affect approximately 0.22 acre of vegetation in wetland and stream buffers (Parametrix
2015a, b) and are not expected to have any substantial effects on habitat quality in these areas.
As noted above, WDNR (2014) has recorded no occurrences of special-status plant species in the study area and biologists observed none during field surveys conducted for this project.
If any undetected populations of any special-status species are present in the project footprint, they would be permanently lost during vegetation clearing.
Wildlife
As noted earlier, the primary way in which trail construction could affect wildlife is through noise and human activity, which may disturb sensitive species and temporarily alter habitat
use. Sources of noise associated with trail construction would include dump trucks, backhoes, graders, pavers, and other machinery. The degree of disturbance would depend on the noise
level, the timing and duration of construction activities, and the sensitivity of individual animals. Construction work would be expected to begin in the late spring of 2016 and would
likely be complete within 1 year. Measures to be implemented to avoid or minimize disturbance to sensitive wildlife species are specified in Section 5.1 (Avoidance and Minimization
Measures).
Animals that are sensitive to disturbance would likely avoid the area while construction is underway. Such effects would be temporary and localized and would not likely influence the
long-term viability of local populations of most species. Potential effects on two species of particular concern, bald eagle and great blue heron, are discussed further in Section 4.1.3,
below.
Under the proposed action, clearing for trail construction would permanently convert vegetated areas within the area of the project footprint to a developed condition. As discussed for
Vegetation, above, clearing is not expected to reduce species diversity or result in a substantial reduction in habitat availability in the study area. Widening of the existing maintenance
road may reduce the amount of cover available for small mammals immediately adjacent to the trail, but suitable cover is abundant throughout the study area. Similarly, the study area
provides ample alternative nesting habitat for bird species that might nest in shrubs and small trees that are cleared for trail widening.
Based on the assessments presented in the discipline reports for wetlands (Parametrix 2015a) and streams (Parametrix 2015b), effects on wetland and stream buffers are not expected result
in decreased habitat quality for amphibians and other species that depend on wetlands for breeding, feeding, resting, and other needs. Habitat replacement would occur through wetland
buffer and stream buffer mitigation, and additional habitat enhancement would be achieved through the planting of native trees and shrubs as visual screening between the trail and the
great blue heron nesting colony (see Section 5.3, Compensatory Mitigation). Additional wetlands are likely present throughout the study area (particularly in the Black River Riparian
Forest), but were not delineated because they are outside of the wetland delineation study area. No temporary or permanent impacts are anticipated to occur to any wetlands. With no
loss of wetland habitat in the project area, local populations of wetland-dependent wildlife species are not expected to be affected.
Vegetation clearing during spring and summer may damage or destroy the nests of migratory birds in the project area. In accordance with the Migratory Bird Treaty Act, King County would
consult with USFWS to identify ways of minimizing harm to migratory birds. The primary means of reducing or eliminating take under the Migratory Bird Treaty Act is to conduct vegetation
clearing and construction activities outside the breeding season, which is typically considered to extend from March 15 through August 31.
Special-status Species
Bald Eagle
No trees suitable for bald eagle nesting, roosting, or perching would be removed by trail construction. Therefore, the project would not be expected to affect the availability of suitable
habitat for bald eagles in the study area.
The nearest bald eagle nest location is more than 1,000 feet from the proposed trail alignment. According to guidelines developed by the USFWS (2007), clearing, construction, and landscaping
activities more than 660 feet away from an active nest are unlikely to cause disturbance to nesting bald eagles. Because the nearest nest is beyond this distance, trail construction
would not be expected to result in any disturbance of nesting bald eagles.
Construction noise and activity have the potential to disturb bald eagles that are foraging in the Black River Riparian Forest or other suitable habitat in adjoining areas. Any eagles
that flush from foraging areas in response to construction activity would likely find ample opportunities to feed in nearby areas that are not within the territories defended by other
nesting pairs. Such areas are readily available along the shorelines of the Green River, Cedar River, and Lake Washington.
Great Blue Heron
No vegetation clearing would take place in forested stands within or immediately adjacent to the Black River nesting colony; therefore, trail construction would have no direct effects
on nesting habitat availability or suitability for great blue herons.
WDFW’s management recommendations for great blue herons state that grading, construction, and vegetation clearing should not occur within a nesting colony or its year-round buffer. As
shown in Figure 4-1, approximately 430 linear feet of the proposed trail alignment falls within the year-round buffer for the Black River nesting colony (i.e., a 656-foot radius from
the outermost nests observed during field investigations; it should be borne in mind that future nesting attempts could occur in locations closer to the proposed trail alignment). At
its nearest point, the trail would be approximately 600 feet from the nesting area.
Although trail clearing and construction would constitute a modification of the landscape within the year-round buffer for the nesting colony, most of the trail alignment is at the edge
of existing disturbed areas associated with the railroad corridor and the concrete recycling plant (Figure 4-1). Vegetation disturbance associated with trail construction would, therefore,
occur at the far edge of the year-round buffer, and would not constitute an incursion into previously undisturbed habitat. In addition, existing vegetation provides visual screening
along portions of the alignment, further reducing the potential for trail construction activities to disturb nesting herons. Even during winter, when branches are bare, no nests are
visible from the trail alignment. It is possible, however, that the effects of grading and construction could be visible to nesting herons—as they fly in and out of the nesting colony,
for example.
Nearly all portions of the proposed trail alignment that are within 656 feet of the colony site consist of the cleared and hardened surface of the existing maintenance road. However,
as noted in Section 4.1.1, Vegetation, the City of Renton has determined that all trees within 10 feet of the paved edge of the trail should be removed, as should all cottonwood trees
within 20 feet of the paved edge of the trail, for the protection of public safety and the trail surface. Approximately nine of the trees proposed for removal are within 656 feet of
the colony site (all are more than 600 feet from the colony site). All of the trees proposed for removal are cottonwoods. Four are between 6 and 10 inches in diameter, 3 are between
10 and 16 inches in diameter, and 2 are between 16 and 20 inches in diameter. Changes in vegetation cover at the edge of the existing disturbed area are not expected to reduce the likelihood
that herons will use the Black River site for breeding or cause herons to abandon active nests. The trail alignment consists of a narrow strip of already disturbed vegetation at the
far edge of the forest stand, and additional clearing would not represent a substantial change in the character of the site. See Section 5.3, Compensatory Mitigation, for a discussion
of the proposed planting of native trees and shrubs as visual
screening between the trail and the great blue heron nesting colony (see Section 5.3, Compensatory Mitigation)
In contrast to most of the trail alignment, which is at the edge of existing disturbed areas north of the Black River Riparian Forest, the easternmost 500 feet of the alignment passes
through an area with forest cover on both sides (Figure 4-1). Construction activities in this area could be perceived by herons as a new source of disturbance, distinct from ongoing
activities in the railroad corridor and the concrete recycling plant. This portion of the alignment is separated from the colony site by approximately 1,300 feet of dense vegetation,
however. The visual screening provided by the distance and vegetation would be expected to minimize the potential for visual disturbance of nesting herons, even early in the breeding
season, before leaf-out is complete.
Noise from construction machinery may be audible within the colony site. Sudden, loud noises may frighten birds off nests, rendering eggs and young more vulnerable to predation. Such
disruptions may diminish reproductive success during the season in which they occur, and could contribute to abandonment of nests or even of the colony. Also, the additional noise sources
could exacerbate stress levels for a nesting colony that has been subject to noise and other disturbance from ongoing activities at the concrete recycling plant and light industrial
development nearby.
The risk of disturbance to nesting herons can be reduced by the implementation of timing restrictions for construction activities that would be visible or audible from the nesting stand.
As noted above, existing vegetation provides visual screening to varying degrees along the entire alignment. To address noise disturbance, WDFW’s management recommendations for great
blue herons advise that unusually loud activities should not be allowed within 1,312 feet (i.e., the 656-foot year-round buffer plus a 656-foot seasonal buffer) of an active colony
from February to September. Approximately 3,500 feet of the proposed trail alignment, from its eastern terminus to a point north of the Black River pump station, falls within the seasonal
buffer for the Black River nesting colony (Figure 4-1).
Machinery and equipment to be used for trail construction would include trucks, backhoes, compressors, and pumps. The average maximum noise levels associated with these types of equipment
do not exceed 83 decibels (WSDOT 2013). Noise from trail construction would not, therefore, exceed the 92-decibel threshold that defines unusually loud activities according to WDFW’s
management recommendations. Nevertheless, to minimize the potential for disturbance to breeding herons, activity restrictions would be implemented for trail construction between January
15 and August 31. These restrictions would apply to activities that are likely to cause disturbance to nesting herons, such as major earthwork and the use of heavy equipment and backup
alarms. Construction activities that employ the use of hand tools would be allowed during the breeding season. Trail construction would not involve any blasting, pile driving, or other
activities that generate high-intensity noise.
Portions of the trail alignment north of the Black River pump station are approximately 250 to 500 feet from stands that have been used as pre-nesting congregation areas. Trail construction
early in the breeding season could disturb birds using these areas, potentially disrupting breeding activities. WDFW recommends minimal disturbance of any area where herons congregate
prior to nesting (Azerrad 2012). The portions of the trail alignment that are near the pre-nesting congregation area are also within the 1,312-foot seasonal buffer around the nesting
area. Implementation of activity restrictions within the seasonal buffer between January 15 and August 31 would, therefore, also reduce or eliminate the potential for disturbance of
herons using the pre-nesting congregation area.
Figure 4-1. Year-round and Seasonal Buffers for the Black River Heron Nesting Colony
The location of the proposed pedestrian bridge is more than 1,312 feet away from the Black River colony (Figure 4 1). Noise from heavy equipment used to stabilize soils and improve load-bearing
capacity for the bridge may be audible in areas that have been identified as pre-nesting congregation areas for the colony, however. Under the terms of the hydraulic project approval
issued by WDFW, construction work near the ordinary high water mark of the river would be restricted to late summer. This work window would not overlap with the pre-nesting period (January
through March, typically) when great blue herons using pre-nesting congregation areas are most sensitive to disturbance (Azerrad 202). Based on the timing of work and the distance from
known nesting areas, therefore, bridge construction work would not be likely to disturb nesting great blue herons.
Construction noise and activity also may disturb great blue herons that are foraging along the Black River or the Green River near the proposed trail alignment. Implementation of activity
restrictions between January 15 and August 31 would reduce the potential for construction activity to disturb foraging herons during the breeding season. Any herons that flush from
foraging areas in response to construction activity would likely find opportunities to feed in nearby areas, such as the Duwamish River, Cedar River, Springbrook Creek, and numerous
isolated ponds and patches of wetland habitat. As discussed in Subsection 4.1.1 above, trail construction is not expected to result in any direct effects on wetlands or net loss of
ecological functions or processes of riparian habitat. In addition, trail construction would not entail any removal of aquatic vegetation, use of watercraft, logging of mature forest,
or removal of perch trees. As a result, trail construction would not be expected to affect foraging habitat suitability.
Western Toad
Trail construction in wetland buffers could affect the quality of breeding habitat for western toads by modifications to wetland hydrology or water quality. The affected wetlands, however,
may be too small to offer sufficient breeding habitat. Western toads are more likely to breed in larger ponds in the study area (Jones et al. 2005), none of which would be affected
by trail construction. Wetland buffer mitigation may result in habitat improvements, although not necessarily within the study area (see the Critical Area Study [Parametrix 2015a]).
Peregrine Falcon
No peregrine falcon nests have been documented within 5 miles of the project area, and no potentially suitable nesting sites occur within 1 mile, so it is extremely unlikely that construction
noise would disturb any nesting falcons. If any falcons are foraging in the area while construction activities are underway, their feeding activities could be disrupted by increased
levels of noise and human activity. Such effects would be temporary and localized, and additional foraging habitat is available nearby.
Pileated Woodpecker
No large trees or snags that provide potential nesting or foraging sites for pileated woodpeckers would be removed for trail construction. If any birds are present while construction
activities are underway, their breeding or feeding activities could be disrupted by increased levels of noise and human activity. Such effects would be temporary and localized, however,
and would not be expected to result in any long-term effects.
Townsend’s Big-eared Bat
Project activities would not be likely to disturb any nursery colonies of Townsend’s big-eared bats because no caves or abandoned buildings occur in the study area, and the structures
in the area are unlikely to provide suitable roosting sites.
Operational Effects
As described above in the discussion of effects during construction, nearly all areas that would be permanently affected by trail development currently consist of hardened surfaces or
non-native plants. Trail maintenance would consist of occasional trimming of plants that may impede trail use, and would not be expected to result in any substantial long-term effects
on vegetation communities or the suitability of wildlife habitat in the study area.
The existing trail currently receives low levels of use for walking, running, bicycling, pet exercise, and bird-watching. These uses would continue on the improved trail, likely at moderate
levels; rates of use would be increased by additional foot and bicycle traffic from persons traveling the length of the Lake to Sound Trail. Increased use of the trail poses an elevated
risk of disturbance to sensitive wildlife species, particularly bald eagles and great blue herons. In addition, the increased presence of domestic dogs along the trail could result
in negative effects on local wildlife populations through direct predation, disruption of breeding activity, or introduction of diseases and parasites. Also, some urban-adapted species
may be attracted into the area by trash left by trail users. Some of these species, such as crows and jays, may prey on eggs and nestlings of sensitive species, including great blue
herons. The following paragraphs address the potential for these factors to result in adverse effects on sensitive wildlife species within and near the study area.
Great blue herons that nest in the Black River Riparian Forest colony may be particularly sensitive to disturbance from trail use and associated activities. The sensitivity of great
blue herons to human disturbance, and the consequences of such disturbance, are discussed in Section 3.4.2. Changes in trail use patterns (i.e., an increase in the number and frequency
of trail users) would increase the potential for disturbance of nesting, foraging, and resting herons. The potential for disturbance to nesting herons would be minimized (but not eliminated)
by the distance of the trail from the nesting area (the area most recently used for nesting is more than 600 feet from the trail alignment at its nearest point). In addition, existing
vegetation provides visual screening to varying degrees along the entire alignment. Even during winter, when branches are bare, no nests are visible from the trail alignment. As noted
above, however, it is possible that trail users could be visible to herons flying into and out of the nesting colony. The potential for disturbance may be further reduced by planting
trees and shrubs along the south side of the trail where existing trailside vegetation does not fully block views of the trail alignment from the heron nesting colony (as noted above,
no nests are visible from the trail, but herons might be able to see the trail from the nesting area). As suggested by Gebauer and Moul (2001), additional vegetation in these areas
would provide additional visual screening, reducing the likelihood of herons being frightened from their nests. Any new plantings would not provide additional screening immediately,
but screening would increase gradually as the mixed plantings of evergreen trees, deciduous trees, and shrubs (see Section 5.3, Compensatory Mitigation) grow taller and more dense.
The location of most of the trail alignment at the edge of the forest, adjacent to currently developed areas, reduces the likelihood that nesting birds would perceive trail use as a
new disturbance. The easternmost 500 feet of the alignment, which passes through an area with forest cover on both sides, is separated from the great blue heron colony site by more
than 1,300 feet of dense vegetation. The visual
and auditory screening provided by the distance and vegetation would essentially eliminate the potential for use of that portion of the trail to disturb nesting herons.
Because the proposed trail route skirts the edge of the Black River Riparian Forest, persons using the trail would not likely be perceived by nesting herons as approaching a nest site.
Generally, wildlife exhibit a stronger response to humans that approach them directly and to humans located off designated trails (MacArthur et al. 1982, Moen et al. 1982, Knight and
Cole 1995, Miller et al. 2001). Burger et al. (2010) found that birds are able to assess relative danger by determining whether a person is approaching directly, as opposed to approaching
tangentially (as would be the case at this location). Trail users would remain at least 600 feet from identified nest trees, further reducing the potential for disturbance. For the
same reason, it is unlikely that raccoons and other mammalian predators would be attracted into the nesting area by trash left by trail users. Even if increased use leads to an increase
in trash accumulation along the trail alignment, there is no assurance that such an increase would attract more mammals to the area, or that any animals would subsequently travel into
the nesting area and prey on herons. Avian predators (e.g., crows and jays), on the other hand, may be more likely than mammals to be attracted to the trail area, and from there to
the nesting colony.
It is possible that increased use of the trail could pose an elevated risk of trail users wandering into the nesting area and disturbing nesting herons. The potential for trail users
to be attracted into the nesting area is minimized by existing vegetation, which obscures views into the nesting area. Even during winter, when branches are bare, no nests are visible
from the trail alignment. The vast majority of trail users are expected to be in the area for trail-based recreation. The presence of dense undergrowth along many portions of the trail
alignment would likely discourage such users from venturing off the trail toward the colony. Persons interested in observing herons would be more likely to use existing viewing areas
accessible via Oakesdale Avenue SW. Determined explorers may not be discouraged by these factors, however. If an overall increase in trail use results in an increase in the number of
such persons in the area, the risk of disturbance to nesting herons would similarly increase. The planting of additional vegetation to reduce the potential for visual disturbance of
nesting herons would also help discourage trail users from straying off the trail. Lastly, the planned installation of fencing and signage on the south side of the trail adjacent to
the Black River Riparian Forest would further reduce the potential for incursions into the nesting area.
Based on recommendations from USFWS (2007), non-motorized recreational activities more than 330 feet from active nests are unlikely to disturb nesting bald eagles. The entire alignment
is more than 330 feet from any current or historical bald eagle nest sites.
MITIGATION
The Lake to Sound Trail—Segment A project would avoid and minimize adverse effects on vegetation and wildlife by proceeding in accordance with the mitigation sequencing requirements
established by NEPA and other statutes and policies. According to implementation regulations at 40 CFR 1508.20, the definition of mitigation is as follows:
Avoiding the impact altogether by not taking a certain action or parts of an action.
Minimizing impacts by limiting the degree or magnitude of the action and its implementation.
Rectifying the impact by repairing, rehabilitating, or restoring the affected environment.
Reducing or eliminating the impact over time by preservation and maintenance operations during the life of the action.
Compensating for the impact by replacing or providing substitute resources or environments.
Avoidance and Minimization Measures
Consistent with the above sequencing requirements, a high priority was placed on designing the project to include measures and features that avoid and minimize adverse effects on vegetation
and wildlife. King County would consult with WDFW and/or the City of Renton to determine appropriate measures to minimize anticipated effects. In accordance with the Migratory Bird
Treaty Act, WSDOT and/or King County would consult with USFWS to identify ways of minimizing harm to migratory birds.
The following measures have been incorporated into the trail design in order to avoid and minimize adverse effects on vegetation and wildlife:
Alignment. The proposed trail follows the perimeter of the Black River Riparian Forest, avoiding habitat fragmentation and disturbance within the central portion of the natural area.
Use of existing disturbed areas. The proposed trail follows existing paths, maintenance roads and disturbed areas (see Section 1.3, Project Area and Setting) to minimize disturbance
of adjacent, existing forest, significant trees, wetlands and buffers, stream buffers, and the species that use these areas.
Strategic widening. In the Black River Riparian Forest, trail widening would occur toward the perimeter, again to avoid the central portion of the natural area and the associated habitat.
Minimizing earthwork. In Fort Dent Park, where the topography is more variable, the trail alignment was selected to follow existing topography to the extent possible and to balance cuts
and fills, reducing the need for retaining walls or large cut or fill areas.
Planting of trees. Where the trail runs adjacent to the Black River Riparian Forest, native trees and shrubs will be planted along the south side of the trail to provide additional visual
screening of the trail from the central portion of the natural area to the south (Appendix B). As these plants grow taller and more dense, they will reduce the potential for trail use
to disturb nesting herons. Plantings will be monitored to ensure establishment and long-term success.
Fencing. Fencing will be placed on the south side of the trail adjacent to the Black River Riparian Forest in areas that appear inviting, to discourage people from accessing the central
portion of the natural area. Vegetation planted for visual screening will further discourage incursions. Other wildlife viewing trails are provided on the south side of the forest.
Wayfinding signage at Naches Avenue SW, Oakesdale Avenue SW, and Monster Road will describe the options.
The following measures would be implemented before and during trail construction to avoid or minimize effects on vegetation and wildlife resources. These strategies would be implemented
along with others designed to avoid or minimize effects on other resources, such as streams, wetlands, and soils. Those strategies would be expected to provide additional protection
to vegetation and wildlife resources within and adjacent to streams and wetlands.
Limit construction activity to a relatively small area immediately adjacent to the existing cleared area to minimize vegetation clearing and leave as much vegetation undisturbed as possible.
Prepare and implement a revegetation plan that emphasizes the use of native species as appropriate.
Where the proposed trail alignment runs adjacent to the Black River Riparian Forest, replace all cleared trees larger than 6 inches in diameter that occur outside critical area buffers
with new trees at a ratio of 1:1 or greater. Include some larger evergreen trees to offset the temporal loss of canopy cover. If City of Renton regulatory requirements result in a
higher replacement ratio, the higher ratio will be used. Note that planting for visual screening between the trail and the great blue heron nesting colony (see Section 5.3, Compensatory
Mitigation) could result in the planting of more trees than would be needed to meet this requirement.
To minimize harm to migratory birds, conduct vegetation clearing and construction activities outside the breeding season, which is typically considered to extend from March 15 through
August 31.
Prevent disturbance of nesting great blue herons and their young due to trail construction and other noise-generating activities by implementing the following measure:
Within 1,312 feet of the Black River heron nesting colony, conduct activities that are likely to disturb nesting herons outside of sensitive periods (i.e., restrictions would apply between
January 15 and August 31). Restricted activities would include major earthwork and the use of heavy equipment and backup alarms. Construction activities that employ the use of hand
tools would not be restricted.
If bald eagles construct a new nest within 660 feet of the trail alignment before construction begins, additional measures, such as timing restrictions on construction activities with
the potential to disturb nesting eagles, may be necessary.
Restoration of Temporary Effects
All areas temporarily affected by construction would be restored to pre-construction conditions and re-planted or seeded with native species. Note that this is a minimum measure; additional
planting for mitigation may occur in some areas, as described in Section 5.1.
Compensatory Mitigation
King County has developed a plan for habitat improvement and restoration to mitigate project-related effects on wetland buffers and stream buffers. All unavoidable impacts to wetland
and stream buffers would be mitigated in accordance with the provisions of the City of Renton Shoreline Master Program (RMC 4-3-090) and City of Tukwila critical areas regulations (TMC
18.44 and 18.45). Details of the mitigation plan are provided in the critical area study prepared for this project (Parametrix 2015a) and summarized in the paragraphs below. The mitigation
plan is also provided as Appendix B to this report.
The mitigation plan focuses on providing compensatory mitigation for riparian buffer and wetland buffer impacts at equal or greater functions than would be affected by the project. The
mitigation sites would be planted at a ratio of at least 1:1 to offset project impacts.
The proposed mitigation sites are located near the proposed trail alignment but outside of the trail right-of-way, within the Black River Riparian Forest natural area (Appendix B). The
first site (Mitigation Site 1) was selected because (1) it overlaps the buffers of potentially affected wetlands and the Black River (2) it is dominated by invasive species, and (3)
it is large enough to accommodate all of the project’s wetland buffer mitigation needs at a single location. The second site (Mitigation Site 2) was selected because it is within the
buffer of the Black River and is adjacent to the trail. Currently proposed Mitigation Site 1 is being used as a natural area and is part of the Black River Riparian Forest. Mitigation
Site 2 is on the sloped banks of the Black River at the western end of the Black River Riparian Forest.
Mitigation for wetland and stream buffer impacts would consist of planting or underplanting native trees and shrubs in an area where existing buffer conditions are degraded. This type
of mitigation would offset the project’s impacts on buffer resources by maintaining or enhancing those functions that support water quality and habitat for fish and wildlife. Proposed
enhancements would include removal of invasive vegetation, tilling of soil, addition of organic soil amendments (where needed) and mulch, and planting of native vegetation.
To supplement the mitigation planting described above, additional mitigation would be provided for tree removal where the proposed trail alignment runs adjacent to the Black River Riparian
Forest in the City of Renton. In that area, all trees larger than 6 inches in diameter would be replaced by new trees at a ratio of 1:1 or greater. Tree planting would occur within
or near Mitigation Sites 1 and 2. Planting for visual screening between the trail and the great blue heron nesting colony (see below) could result in the planting of more trees than
would be needed to meet this commitment.
In addition to the habitat improvements described above, native trees and shrubs would be planted along approximately 250 feet of the trail to provide additional visual screening between
the trail and the great blue heron nesting colony. These additional plantings would be located west of the nesting colony, where views toward the colony are not already obscured by
existing vegetation. The plantings would consist of both evergreen and deciduous trees to block views, as well as densely growing shrubs to discourage pedestrians from venturing off
the trail. The plantings would include seedlings along with some more mature evergreens, to offset some of the temporal loss of canopy cover. Such plantings, combined with fence installation
along the southern edge of the alignment of the trail adjacent to the Black River Riparian Forest, are expected to reduce the potential for disturbance to wildlife in the natural area.
The City of Tukwila does not specify required compensatory mitigation ratios for impacts to wetland buffers or stream buffers. Impacts to wetland buffers and stream buffers are generally
replaced at a ratio of 1:1. The Black River Riparian Forest falls within the jurisdiction of the City of Renton’s Shoreline Master Program, which specifies a replacement ratio of 1:1
for impacts to wetland buffers. Any trees with trunks larger than 4 inches in diameter that are removed within sensitive areas or shoreline zones in the City of Tukwila would be replaced
as prescribed by TMC requirements.
REFERENCES
Anderson, C. 2011. Personal communication of February 9, 2011. Wildlife biologist, Washington Department of Fish and Wildlife, Mill Creek, Washington.
Audubon Society. 2011. Database search of Christmas Bird Count data for the Seattle and Kent-Auburn survey areas, 2000–2010. Available at: http://birds.audubon.org/historical-results.
Accessed September 19, 2011.
Azerrad, J.M. 2012. Great Blue Heron. Pages 3-1 through 3-18. In E. Larsen, J.M. Azerrad, and N. Nordstrom, editors. Management Recommendations for Washington’s Priority Species, Volume
IV: Birds. Washington Department of Fish and Wildlife, Olympia, Washington.
Burger, J., M. Gochfeld, C. Jenkins, and F. Lesser. 2010. Effect of approaching boats on nesting black skimmers: using response distances to establish protective buffer zones. Journal
of Wildlife Management 74:102-108.
Butler, R.W. 1997. The great blue heron. University of British Columbia Press, Vancouver, British Columbia. 184 pp.
Chatwin, T., T. Dunlop, and R. Joy. 2009. Pacific great blue heron population and monitoring: Vancouver Island and the Gulf Islands 2007 and 2008. B.C. Ministry of Environment, Victoria,
British Columbia. Wildlife Working Report No. WR 119. 43 pp.
City of Vancouver Parks and Recreation. 2006. Stanley Park heronry management plan. Vancouver, British Columbia.
COSEWIC (Committee on the Status of Endangered Wildlife in Canada). 2008. COSEWIC assessment and update status report on the Great Blue Heron fannini subspecies Ardea herodias fannini
in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa, Ontario. Available at: http://www.sararegistry.gc.ca/document/default_e.cfm?documentID=1614. Accessed June
7, 2013.
Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of wetlands and deepwater habitats of the United States. Government Printing Office, Washington, D.C.
Franklin, J.F. and C.T. Dyrness. 1988. Natural vegetation of Oregon and Washington. Corvallis, OR: Oregon State University Press.
Gebauer, M.B. and I.E. Moul. 2001. Status of the Great Blue Heron in British Columbia. B.C. Ministry of Environment, Lands, and Parks, Wildlife Branch. Victoria, British Columbia. Wildlife
Working Report Number 102.
Hamilton, M. 2013. Personal communication of January 15, 2013. Wildlife photographer, Issaquah, Washington.
Hays, D.W. and R. Milner. 2004. Peregrine falcon (Falco peregrinus). In E.M. Larsen, J.M. Azerrad, and N. Nordstrom, editors. Management Recommendations for Washington’s Priority Species,
Volume IV: Birds. Washington Department of Fish and Wildlife, Olympia, Washington.
Jackson, S.D. 2003. Ecological considerations in the design of river and stream crossings. In Proceedings of the International Conference on Ecology and Transportation, edited by C.
Leroy Irwin, Paul Garrett, and K.P. McDermott. Raleigh, NC: Center for Transportation and the Environment, North Carolina State University. 10 pp.
Johnson, R.E. and K.M. Cassidy. 1997. Mammals of Washington state: location data and modeled distributions. Washington State GAP Analysis, Volume 3. Washington Cooperative Fish and Wildlife
Research Unit, Seattle, Washington.
Johnson, D.H. and T.A. O’Neil (managing directors). 2001. Wildlife-habitat relationships in Oregon and Washington. Oregon State University Press, Corvallis, Oregon.
Jones, L.L.C., W.P. Leonard, and D.H. Olson, eds. 2005. Amphibians of the Pacific Northwest. Seattle Audubon Society, Seattle, Washington. 227 pp.
Kenyon, J.K. 2005. Behaviours influencing the distribution of the Great Blue Herons (Ardea herodias fannini) in the Strait of Georgia, British Columbia. MSc Thesis, Simon Fraser University.
97 pp.
Knight, R. L., and D. N. Cole. 1995. Wildlife responses to recreation. Pages 51-69 in R. L. Knight and K. J. Gutzwiller, editors. Wildlife and recreationists: coexistence through management
and research. Island Press, Washington, D.C., USA.
Lewis, J.C. and J.M. Azerrad. 2003. Pileated woodpecker (Dryocopus pileatus). In E.M. Larsen, J.M. Azerrad, and N. Nordstrom, editors. Management Recommendations for Washington’s Priority
Species, Volume IV: Birds. Washington Department of Fish and Wildlife, Olympia, Washington.
MacArthur, R. A., V. Geist, and R. H. Johnson. 1982. Cardiac and behavioral responses of mountain sheep to human disturbance. Journal of Wildlife Management 46:351-358.
Miller, S. G., R. L. Knight, and C. K. Miller. 2001. Wildlife responses to pedestrians and dogs. Wildlife Society Bulletin 29:124-132.
Moen, A. N., S. Whittemore, and B. Buxton. 1982. Effects of disturbance by snowmobiles on heart rate of captive white-tailed deer. New York Fish and Game Journal 29: 474-488.
Opperman, H., K.M. Cassidy, T. Aversa, E.S. Hunn, and B. Senturia. 2006. Sound to Sage: Breeding Bird Atlas of Island, King, Kitsap, and Kittitas Counties, Washington. Published at:
http://www.soundtosage.org by the Seattle Audubon Society. Version 1.1, September 2006.
Parametrix. 2015a. Lake to Sound Trail – Segment A: Final Critical Area Study. April, 2015. Seattle, Washington.
Parametrix. 2015b. Lake to Sound Trail – Segment A: Stream Discipline Report. Seattle, Washington.
Quinn, T. and R. Milner. 2004. Great Blue Heron. Pages 3-1 through 3-7. In E.M. Larsen, J.M. Azerrad, and N. Nordstrom, editors. Management Recommendations for Washington’s Priority
Species, Volume IV: Birds. Washington Department of Fish and Wildlife, Olympia, Washington.
Stenberg, K. 2007. The Black River Heron Colony: An Annotated History. Quailcroft Environmental Services, Sammamish, Washington.
Stinson, D.W., J.W. Watson, and K.R. McAllister. 2001. Washington State status report for the bald eagle. Washington Department of Fish and Wildlife, Olympia, Washington. 92 pp.
USFWS (U.S. Fish and Wildlife Service). 2007. National bald eagle management guidelines. May 2007. Available at: http://www.fws.gov/pacific/eagle/guidelines/disturbnestingbaea1.html.
USFWS (U.S. Fish and Wildlife Service). 2015a. Information, Planning, and Conservation System. Available at: http://ecos.fws.gov/ipac/. Accessed January 16, 2015.
USFWS (U.S. Fish and Wildlife Service). 2015b. U.S. Fish and Wildlife Service critical habitat mapper. Available at: http:// http://ecos.fws.gov/crithab/. Accessed February 2, 2015.
Vennesland, R.G. 2000. The effects of disturbance from humans and predators on the breeding decisions and productivity of the Great Blue Heron in south-coastal British Columbia. M.Sc.
thesis. Simon Fraser University, Burnaby, British Columbia.
Vennesland, R.G. and R.W. Butler. 2004. Factors influencing Great Blue Heron nesting productivity on the Pacific coast of Canada from 1998 to 1999. Waterbirds 27: 289-296.
Watson, J.W. and E.A. Rodrick. 2004. Bald eagle (Haliaeetus leucocephalus). In E.M. Larsen, J.M. Azerrad, and N. Nordstrom, editors. Management Recommendations for Washington’s Priority
Species, Volume IV: Birds. Washington Department of Fish and Wildlife, Olympia, Washington.
WDFW (Washington Department of Fish and Wildlife). 2008. Priority Habitat and Species List. Olympia, Washington. 177 pp.
WDFW (Washington Department of Fish and Wildlife). 2015. PHS on the Web: An interactive map of WDFW priority habitats and species information for project review. Available online at:
http://wdfw.wa.gov/mapping/phs/. Accessed February 2, 2015.
WDFW (Washington Department of Fish and Wildlife). 2014. Salmonscape fish database and mapping application. Available online at: https://fortress.wa.gov/dfw/salmonscape/. Accessed January
16, 2014.
WDFW (Washington Department of Fish and Wildlife). 2011. Priority habitats and species maps and data for the vicinity of Section 13, Township 24 North, Range 1 East. Received on February
16, 2011.
WDNR (Washington Department of Natural Resources). 2014. Washington Natural Heritage Program GIS data. Olympia, Washington.
Woodruff, K. and H. Ferguson. 2005. Townsend’s big-eared bat (Corynorhinus townsendii). In J.M. Azerrad, editor. Management Recommendations for Washington’s Priority Species, Volume
V: Mammals. Washington Department of Fish and Wildlife, Olympia, Washington.
WSDOT (Washington State Department of Transportation). 2010. Ethnobotany and cultural resources. Available at: http://www.wsdot.wa.gov/Environment/CulRes/ethnobotony.htm. Accessed December
28, 2010.
WSDOT (Washington State Department of Transportation). 2013. Biological assessment preparation advanced training manual. Version 02-2013. Available at: http://www.wsdot.wa.gov/Environment/Biology/BA
/BAguidance.htm. Accessed February 20, 2013.
Bird Species Likely to Occur in the Lake to Sound Trail—Segment A Study Area