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CEDAR RIVER BROODSTOCK COLLECTION
FACILITY REPLACEMENT
CRITICAL AREAS REPORT
Prepared for:
Seattle Public Utilities
July 30, 2020
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146 N Canal St, Suite 111 • Seattle, WA 98103 • www.confenv.com
Cedar River Broodstock Collection Facility Replacement
CRITICAL AREAS REPORT
Prepared for:
Seattle Public Utilities
700 Fifth Avenue, Suite 4500
Seattle, WA 98124-5177
Attn: Michael Norton, Fernando Platin, Clayton Antieau
Authored by:
Confluence Environmental Company
July 30, 2020
This report should be cited as:
Confluence (Confluence Environmental Company). 2020. Cedar River broodstock collection facility replacement, critical areas
report. Prepared for Seattle Public Utilities, Seattle, Washington, by Confluence, Seattle, Washington.
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TABLE OF CONTENTS
1.0 INTRODUCTION .............................................................................................................................................. 1
1.1 Regulatory Setting ............................................................................................................................. 1
1.2 Purpose of Report ............................................................................................................................. 2
2.0 METHODS ........................................................................................................................................................ 4
2.1 Desktop Analysis ............................................................................................................................... 4
2.2 Wetlands ........................................................................................................................................... 4
2.2.1 Wetland Identification and Delineation ................................................................................ 4
2.2.2 Wetland Rating .................................................................................................................... 5
2.3 Ordinary High Water Mark Delineation .............................................................................................. 5
3.0 RESULTS ......................................................................................................................................................... 6
3.1 General Site Conditions and Surrounding Land Use ......................................................................... 6
3.2 Shoreline and OHWM ........................................................................................................................ 6
3.3 Habitat Conservation Areas ............................................................................................................... 8
3.4 Wetlands ........................................................................................................................................... 8
3.5 Flood Hazard Areas........................................................................................................................... 9
3.6 Wellhead Protection Areas ................................................................................................................ 9
3.7 Geologic Hazard Areas ................................................................................................................... 10
4.0 PROJECT DESCRIPTION ............................................................................................................................. 10
4.1 Project Elements ............................................................................................................................. 12
4.1.1 Concrete Sill ...................................................................................................................... 12
4.1.2 Picket Weir ........................................................................................................................ 15
4.1.3 Picket Lift System .............................................................................................................. 15
4.1.4 Improved Trap Box Assembly ........................................................................................... 16
4.1.5 Civil Site Improvements .................................................................................................... 18
4.2 Construction .................................................................................................................................... 19
4.2.1 Construction Schedule and Phasing ................................................................................. 20
4.2.2 Phase 2 Staging/Laydown Areas ...................................................................................... 21
4.2.3 In-Water Work ................................................................................................................... 21
4.2.4 Upland Work ..................................................................................................................... 24
4.3 Best Management Practices ............................................................................................................ 24
4.4 Operations and Maintenance .......................................................................................................... 27
5.0 IMPACT ASSESSMENT ................................................................................................................................ 28
5.1 Avoidance and Minimization of Impacts .......................................................................................... 28
5.2 Temporary Impacts.......................................................................................................................... 28
5.2.1 Cedar River Temporary Impacts ....................................................................................... 30
5.2.2 Riparian Buffer Temporary Impacts .................................................................................. 31
5.3 Permanent Impacts ......................................................................................................................... 31
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5.3.1 Cedar River Permanent Impacts ....................................................................................... 33
5.3.2 Riparian Buffer Permanent Impacts .................................................................................. 34
6.0 COMPENSATORY MITIGATION ................................................................................................................... 35
6.1 Applicable Regulations .................................................................................................................... 35
6.2 Proposed Compensatory Mitigation ................................................................................................ 36
6.2.1 Conceptual Mitigation Design............................................................................................ 37
6.2.2 Mitigation Ratios ................................................................................................................ 41
6.2.3 Ecological Benefits ............................................................................................................ 41
7.0 MITIGATION GOALS, OBJECTIVES, AND PERFORMANCE CRITERIA .................................................... 43
7.1 Goals ............................................................................................................................................... 43
7.2 Objectives ........................................................................................................................................ 43
7.2.1 Objective 1 – Woody Riparian Buffer ................................................................................ 44
7.2.2 Objective 2 – Trophic Support ........................................................................................... 45
7.2.3 Objective 3 – Invasive Species ......................................................................................... 46
7.2.4 Objective 4 – LWM Complex ............................................................................................. 46
8.0 MAINTENANCE ............................................................................................................................................. 47
9.0 FINANCIAL ASSURANCES........................................................................................................................... 47
10.0 LONG-TERM MANAGEMENT AND SITE PROTECTION ............................................................................. 47
11.0 REFERENCES ............................................................................................................................................... 48
TABLES
Table 1. Summary of Temporary Impacts .................................................................................................................... 30
Table 2. Summary of Permanent Impacts .................................................................................................................... 33
Table 3. Proposed Plant Schedule ............................................................................................................................... 39
Table 4. Proposed Mitigation Ratios ............................................................................................................................ 41
Table 5. Performance Criteria ...................................................................................................................................... 43
FIGURES
Figure 1. Project Limits and Study Area ......................................................................................................................... 3
Figure 2. Proposed Site Plan Drawings Showing Project Elements ............................................................................ 14
Figure 3. Temporary Unavoidable Project Impacts ...................................................................................................... 29
Figure 4. Permanent Unavoidable Project Impacts ...................................................................................................... 32
Figure 5. Proposed Mitigation Concept ........................................................................................................................ 40
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APPENDICES
Appendix A—GIS Database Search Results
Appendix B—BCF 60% Design Drawings
Appendix C—Wetland Delineation Methods
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ACRONYMS AND ABBREVIATIONS
BA Biological Assessment
BCF Broodstock Collection Facility
BMP best management practices
cfs cubic feet per second
Confluence Confluence Environmental Company
COR commercial office/residential land use
Corps U.S. Army Corps of Engineers
cy cubic yard
Ecology Washington State Department of Ecology
EIS Environmental Impact Statement
ESA Endangered Species Act
HCA habitat conservation area
HPA Hydraulic Project Approval
I-405 Interstate 405
ILF in lieu fee
ILFP in lieu fee program (part of King County Mitigation Reserves Program)
JARPA Joint Aquatic Resources Permit Application
NMFS National Marine Fisheries Service
NRCS National Resources Conservation Service
OHWM ordinary high water mark
PVC polyvinyl chloride
RCW Revised Code of Washington
RMC Renton Municipal Code
SEPA State Environmental Policy Act
SMP Shoreline Master Program
SPCC Spill Prevention, Control, and Countermeasure
SPU Seattle Public Utilities
SR State Route
TESC temporary erosion and sedimentation control
TSS total suspended solids
USFWS U.S. Fish and Wildlife Service
WAC Washington Administrative Code
WDFW Washington Department of Fish and Wildlife
WDNR Washington Department of Natural Resources
WPA wellhead protection area
WSDOT Washington State Department of Transportation
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1.0 INTRODUCTION
The City of Seattle’s Seattle Public Utilities (SPU) is proposing improvements to the existing
Cedar River Sockeye Hatchery Program’s Broodstock Collection Facility (BCF) (the project).
As a condition of the Landsburg Mitigation Agreement (LMA) in 2000 (City of Seattle 2000), the
Cedar River Sockeye Hatchery Program (Program) was developed to mitigate habitat lost to
spawning sockeye salmon (Oncorhynchus nerka) above the Landsburg Diversion Dam. The LMA
describes mitigation and monitoring required in response to the diversion of SPU’s municipal
water supply system at the Landsburg Diversion Dam in the Cedar River. The BCF is a critical
component of the Program, which is described in the LMA. The BCF is a removable trap and
weir system used to capture adult sockeye salmon for hatchery broodstock. The operational
objective for the BCF is to supply sufficient broodstock to meet the annual hatchery production
goal of 34 million sockeye fry. This equates to approximately 26,000 adult sockeye per year.
The existing BCF is located on the lower Cedar River at river mile (RM) 1.7, approximately 66
feet upstream from the Interstate 405 (I-405) bridge crossing in Renton, Washington. The site is
in Washington Township and Range T23N R5E S18 at latitude/longitude 47.480716° N,
122.199027° W (HUC 171100120106, Lower Cedar River).
The proposed project improvements include the construction of a permanent foundation for the
BCF in the active river channel, and improvements to the removable weir and trap system to
increase operational efficiency and safety. The proposed project would be constructed
immediately upstream of the existing facility. The study area assessed in this report
encompasses the extent of any proposed construction activities (the project limits) and an
additional 200 feet from the project limits, per the largest critical area buffer width included in
the Renton Municipal Code (RMC) 4-3-050.G.2. The study area and project limits are shown in
Figure 1.
1.1 Regulatory Setting
The following City of Renton (Renton) regulations apply to the construction and operation of
the proposed BCF.
Habitat Conservation Areas (HCAs) are regulated as critical areas pursuant to RMC 4-3-
050.B.1.c. HCAs are not defined in RMC 4-11-080; however, RMC 4-3-050.B classifies HCAs as
critical habitats that have a primary association with documented presence of salmonid species
listed by the Federal government or State of Washington as endangered, threatened, sensitive
and/or of local importance. This applies to the project site due to the presence of federally listed
Puget Sound Chinook salmon (Oncorhynchus tshawytscha) and Puget Sound steelhead (O.
mykiss).
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Wetlands, flood hazard areas, wellhead protection areas, and geologic hazard areas are also
regulated as critical areas pursuant to RMC 4-3-050. Development standards and alteration
provisions that apply to these critical areas are included in RMC sections 4-3-050.G, 4-3-050.H,
4-3-050.I, and 4-3-050.J.
Renton additionally administers the State Shoreline Management Act (90.58 RCW) to protect all
shorelines within its jurisdiction. Within Renton’s Shoreline Master Program (SMP), shoreline
areas of the state are identified and designated, and include eligible waters, the area 200 feet
landward from the ordinary high water mark (OHWM) of the waters (“shorelands”), and
associated wetlands (if they extend beyond the 200-foot boundary). The SMP codified in RMC
4-3-090 outlines high-level policies to protect these natural resources, and general development
standards require that environmental effects of uses and development activities are analyzed
and no net loss of ecological functions would occur pursuant to RMC 4-3-090.D.2.
1.2 Purpose of Report
Confluence Environmental Company (Confluence) developed this report on behalf of SPU to
satisfy local permitting and compliance with Renton critical area regulations located in RMC 4-
3-050 and shoreline ecological functions pursuant to RMC 4-3-090.D.2. In September of 2018,
Confluence conducted a site visit to the BCF to determine the presence and extent of critical
areas on and adjacent to the BCF. The effort was focused on wetlands, streams, and HCAs as
defined in RCM 4-3-050. An OHWM delineation of the Cedar River was also completed. This
report discusses the critical areas identified on or adjacent to the project limits and includes a
description of the project, anticipated project impacts, and the proposed mitigation plan to
compensate for any loss of ecological functions to critical areas and aquatic resources.
The proposed project would result in unavoidable impacts to HCAs and the shoreline
environment. The proposed mitigation plan described herein includes an assessment of those
unavoidable impacts and a strategy for impact mitigation pursuant to:
RMC 4-3-050.G.6.d
RMC 4-3-090.D.2.a
RMC 4-3-090.D.2.c
Also discussed are ways in which potential project impacts have been avoided and minimized
to the extent feasible. This report supports Renton requirements to obtain necessary clearing,
grading, and shoreline permits.
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Figure 1. Project Limits and Study Area
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2.0 METHODS
This section describes the methods used to identify and evaluate critical areas by Confluence
during the September 2018 site visit.
2.1 Desktop Analysis
Confluence evaluated the study area for the presence of critical areas using available GIS
databases. The following databases were reviewed:
King County iMap (King County 2020),
City of Renton Maps of Your Community (City of Renton 2020),
U.S. Fish and Wildlife Service (USFWS) National Wetlands Inventory (NWI) (USFWS
2020),
National Resources Conservation Service (NRCS) Web Soil Survey (NRCS 2020a),
Washington Department of Fish and Wildlife (WDFW) SalmonScape (WDFW 2020a),
WDFW Priority Habitat and Species (WDFW 2020b), and
Washington Department of Natural Resources (WDNR) Water Type GIS (WDNR 2020).
Results of the GIS database searches are in Appendix A.
2.2 Wetlands
2.2.1 Wetland Identification and Delineation
Confluence uses the methods described by the U.S. Army Corps of Engineers (Corps) in the
Corps of Engineers Wetland Delineation Manual (Corps 1987) and the Regional Supplement to
the Corps of Engineers Wetland Delineation Manual: Western Mountains, Valleys, and Coast
Region (Regional Supplement; Corps 2010) to determine the presence of and delineate wetland
boundaries. The Corps usually requires that the following 3 characteristics be present for an
area to be identified as a wetland: (1) hydrophytic vegetation, (2) hydric soil, and (3) wetland
hydrology.
To assess whether there were possible wetlands on or encroaching from adjacent properties,
Confluence modified the methods described by the Corps (Corps 1987, 2010) The modified
method identifies the presence or absence of visual wetland indicators. If dominant hydrophytic
vegetation and visual indicators of wetland hydrology were observed, then a detailed
determination and delineation would follow.
The PLANTS Database (NRCS 2020b) was used for scientific names and the 2016 National
Wetland Plant List (Lichvar et al. 2016) was used to determine the wetland indicator status of
plants.
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2.2.2 Wetland Rating
In the event that wetlands were identified within or adjacent to the study area, Confluence
would determine wetland ratings using the Washington State Wetland Rating System for
Western Washington (Hruby 2014) to assess the resource value of the wetlands identified on the
site. This rating system is based on the wetland functions and values, sensitivity to disturbance,
rarity, and irreplaceability.
2.3 Ordinary High Water Mark Delineation
The Washington State Code defines the OHWM as “on all lakes, streams, and tidal water is that
mark that would be found by examining the bed and banks and ascertaining where the
presence and action of waters are so common and usual, and so long continued in all ordinary
years, as to mark upon the soil a character distinct from that of the abutting upland, in respect
to vegetation as that condition exists on June 1, 1971, as it may naturally change thereafter, or as
it may change thereafter in accordance with permits issued by a local government or the
department” (RCW 90.58.030).
Washington State Department of Ecology (Ecology) has published a guide (Anderson et al.
2016) to interpret the code and provide guidance for field OHWM determinations. Confluence
used this guidance to determine the OHWM of the Cedar River in the vicinity of the BCF.
Confluence identified discrete locations on the right (north) and left (south) bank of the stream
to delineate the OHWM. Locations were chosen based on presence of field indicators of OHWM
identified in Anderson et al. (2016) and shape of the channel. The location of the OHWMs were
marked with either survey ribbon or pin flags within the study area and were recorded using a
differential GPS with sub-meter accuracy.
Habitat conditions of the Cedar River and associated riparian areas throughout the study area
were qualitatively assessed.
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3.0 Results
The following subsections give an overview of the current condition of the landscape setting,
and the resources located within the study area that may be impacted by the project. Critical
areas evaluated for the study area discussed in this report include wetlands, streams, HCAs,
wellhead protection areas (WPAs), flood hazard areas, and geologic hazard areas (GHA).
3.1 General Site Conditions and Surrounding Land Use
The existing BCF is located in a highly developed urban area with commercial, industrial, and
recreational facilities/amenities nearby. The project site is located in a community park on the
edge of the developed urban core of Renton. The areas surrounding the study area are bisected
by 2 regional transportation corridors, I-405 and State Route (SR) 169, as well as local roads and
a regional bike trail. The city park on the north (right) bank consists of maintained lawns and
paved walkways. The park area on the south (left) bank includes a narrow vegetated riparian
zone, paved access to the river for the existing BCF, and a regional bike trail. The riparian area
adjacent to the Cedar River, on both the north and south banks, is zoned for commercial
office/residential land use (COR) (City of Renton 2020). Upstream of the BCF, much of the south
bank of the Cedar River is forested and zoned as Resource Conservation, while the north bank
is dominated by commercial, industrial, and residential land uses, and zoned as COR (City of
Renton 2020). Natural habitats in the study area and vicinity are routinely subjected to
disturbance by vehicle traffic, recreational activity, and related uses.
The existing BCF is operated seasonally, typically from September through November, by
WDFW. Typically, the weir is installed after Labor Day and removed in late October or early
November as a result of increasing flows that create unsafe conditions for hatchery personnel
and collected fish. The current design consists of resistance-board panels constructed from off-
the-shelf materials, such as polyvinyl chloride (PVC) conduit. The substrate rail and vehicle
access ramp on the left bank constitute the only permanent facility components. The substrate
rail is composed of buried angled iron with winged struts that extend 3 feet upstream, anchored
to the riverbed with rebar stakes.
3.2 Shoreline and OHWM
The Cedar River is a Type S waterbody (a “shoreline of the state” as defined in Chapter
90.58.030 of the Revised Code of Washington [RCW] [WDNR 2020]). It is defined as an aquatic
shoreline environment by the City of Renton (RMC 4-3-090). As a shoreline of the state, the
Cedar River is regulated under Renton’s SMP in RMC Section 4-3-090 and not under RMC
Section 4-3-050. Included within shoreline jurisdiction are floodways and all lands within 200
feet of the OHWM (RMC 4-3-090), including the entire project limits and study area. Both the
in-water and upland components of the project would occur within shoreline jurisdiction. The
OHWM of the Cedar River was delineated through the project limits and immediately
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upstream, showing that there are approximately 380 linear feet of shoreline and 16,970 square
feet of the Cedar River within the project limits (refer to Figure 1).
The shoreline habitat within the project limits includes the Cedar River channel, a sparsely
forested riparian buffer to the south, and a maintained lawn to the north. No aquatic vegetation
was observed below the OHWM within the project limits. The Cedar River through this reach is
characterized by a single channel through low-amplitude meanders and a gradient of less than
0.3%, resulting in a depositional reach. The lower Cedar River has been extensively modified
from its historical condition. Gendaszek et al. (2012) classified the river as entirely contained by
revetments or other bank-stabilizing structures from the mouth to approximately RM 1.9. This
has resulted in a mainstem channel dominated by riffle environments and riparian areas that
are either devoid of large trees or, if forested, are dominated typically by alders and large
cottonwood, rather than conifers (Kerwin 2001).
The downstream hard bank stabilization on the south bank of the river appears to end at I-405,
meaning that the portion of the study area within the project footprint is partially unconfined
and stabilized by native vegetation. The north bank is stabilized by a permanent concrete wall
along the shore of Cedar River Park and riprap revetment underneath the highway. No actively
eroding streambanks exist in the study area. The right bank is largely disconnected from the
floodplain by armored revetments; the left bank retains partial connectivity to a relatively
narrow vegetated floodplain. The remainder of the Cedar River beginning at I-405 downstream
to the mouth of Lake Washington is contained within armored levees and the floodplain is
entirely developed.
The study area and vicinity are generally characterized by simplified, uniform riffle and glide
habitat. Pools are infrequent, and where present are formed by scour around artificial
structures, including bridge abutments and bank armoring. One such pool occurs at the
upstream edge of the retaining wall on the right bank approximately 90 feet upstream of the
proposed BCF.
Otherwise, the river in the study limits lacks channel complexity. An artificial backwater area is
present on the right bank immediately upstream of the study area. This area is routinely used
for public water access and does not provide high-quality refuge. The channel downstream of
the study area is straightened and contained within levees, providing little or no high-flow
refuge. No off-channel ponds are present. Based on physical observations and prior sediment
grain size analyses, it appears that substrate composition in the study area is dominated by fine
to medium gravel. The study area has effectively no functional large woody material (LWM)
present. Riparian conditions within and upstream of the study area are degraded and do not
currently support steady LWM recruitment.
Salmonid species known to occur within the study area include fall Chinook salmon, coho
salmon (O. kisutch), sockeye salmon/kokanee, and winter steelhead or resident rainbow trout
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(WDFW 2020a). Of these species, Chinook salmon, coho salmon, and sockeye salmon have been
documented to spawn within the project reach, and steelhead are thought to rear, and
potentially spawn, within the project limits (WDFW 2020a).
The land cover within the shorelands on the south (left) bank includes a narrow vegetated
riparian zone, paved access to the river for the existing BCF, a regional bike trail, and open
fields. It is generally characterized by a high terrace sloping steeply down to a narrow flood
terrace along the Cedar River in the vicinity of the BCF. Soils within the project limits are
mapped as either Riverwash—alluvial deposits found in frequently flooded drainageways—
and Urban land (NRCS 2020a). Soils in the riparian zone on the south bank generally match this
description and appear to be dominated by sand-sized particles. Vegetation within the riparian
zone below the high terrace consisted of a mix of native and non-native species. Native
vegetation includes, but is not limited to, an overstory of big-leaf maple (Acer macrophyllum),
black cottonwood (Populus balsamifera), and red alder (Alnus rubra), with an understory
composed of red-osier dogwood (Cornus sericea), snowberry (Symphoricarpos alba), beaked
hazelnut (Corylus cornuta), Indian plum (Oemleria cerasiformis), Pacific ninebark (Physocarpus
capitatus), and Western red-cedar (Thuja plicata). Invasive vegetation includes Japanese
knotweed (Polygonum cuspidatum), English ivy (Hedera helix), and Himalayan blackberry (Rubus
armeniacus). A recent flood event in February 2020 damaged the riparian plant community, by
largely eroding bank sediments and leaving only a few trees and some Himalayan blackberry.
Overall, the aquatic and riparian habitat in the project limits consists of low- to moderate-
intensity land use and is relatively disturbed. These habitats provide ecological benefits for
salmonids and non-salmonid fishes, including spawning, migration, and rearing habitat, and
shade and food inputs from the south bank.
3.3 Habitat Conservation Areas
The Cedar River is also regulated as a Habitat Conservation Area. The city classifies HCAs as
those habitats “that have a primary association with the documented presence of non-salmonid
or salmonid species proposed or listed by the Federal government or State of Washington as
endangered, threatened, sensitive, and/or of local importance” (RMC 4-3-050). Because the
Cedar River contains Puget Sound Chinook salmon and Puget Sound steelhead, which are
federally listed threatened species, the Cedar River constitutes an HCA regulated under RMC 4-
3-050.G.6 and a Class 1 Fish Habitat Conservation Area under RMC 4-3-090.D.2.c.ii.
3.4 Wetlands
According to NWI, there are no wetlands within or near the BCF (USFWS 2020). The nearest
wetland is located in Riverview Park, approximately 1 mile from the project limits (USFWS
2020). The lack of on-site wetlands was verified by observations made by Confluence during the
September 2018 site visit. Site conditions are such that no test plots or soil probes were required
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to confirm the lack of wetland habitat. As no wetlands or wetland buffers were identified
within the study area, wetlands will not be discussed further in this report. For a map of off-site
wetlands, please see Appendix A.
3.5 Flood Hazard Areas
The Federal Insurance Administration identified all the flood hazard areas within the City of
Renton in their 1989 report entitled the “Flood Insurance Study for the City of Renton” (RMC 4-
3-050). Updates have since been made as the Federal Emergency Management Agency (FEMA)
issued a review period in 2017 for all Digital Flood Insurance Rate Maps.
As an in-water feature, the BCF occurs in the preliminary floodway of the Cedar River (City of
Renton 2017). Approximately 70 feet of the riparian area on the south bank and 30 feet on the
north bank also occur within the preliminary floodway, while the upper 30 to 40 feet of the
riparian area on the south bank and approximately 60 feet on the north bank falls within the
100-year floodplain (King County 2020). The city designates the upper portion of the south bank
as Zone X, which refers to those areas with a 0.2% annual chance flood, 1% annual chance flood
with average depths of less than 1 feet within a drainage area of less than 1 square mile, and
those areas protected from the 1% annual chance flood by levees (City of Renton 2020). The
upper portion of the north bank is designated as Zone AE, meaning base flood elevations have
been determined, which refers to the water surface elevation of the 1% annual chance flood
(City of Renton 2017). For a map of flood hazard areas, please see Appendix A.
A no-rise condition analysis was conducted to ensure that the placement of the BCF permanent
weir would not cause an increase in flood levels within the Cedar River floodplain during the
occurrence of the base (100-year) flood discharge. A Hydrologic Engineering Center River
Analysis System (HEC-RAS) model was provided to McMillen Jacobs by the City of Renton.
The HEC-RAS model was modified to include the BCF permanent weir and determined that the
BCF permanent weir would have a no-rise effect on the 1% annual chance flood or base flood
elevation, if the weir elevation is at or below elevation 29.6 feet. In addition, the BCF permanent
weir does not affect the floodway widths for the with floodway 1% annual chance flood water
surface elevations. Additional detail on the FEMA no-rise certification can be found in the
submitted No-Rise Study (McMillen Jacobs 2020).
3.6 Wellhead Protection Areas
The city defines WPAs as the “portion of the aquifer within the zone of capture and recharge
area for a well owned or operated by the City” in RMC 4-3-050.G.8. The BCF occurs within the
downtown WPA, known as Zone 1, which encompasses much of downtown Renton, the Cedar
River, and associated riparian areas through Riverview Park (City of Renton 2020). Components
of the proposed BCF do not appear to be subject to the development and alteration standards
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for WPAs, and, therefore, WPAs will not be discussed further in this report. For a map of
WPAs, please see Appendix A.
3.7 Geologic Hazard Areas
Geologic hazard areas are defined by the city as those areas with steep slopes (minimum
vertical rise of 15 feet), landslide hazards, erosion hazards, seismic hazards, and/or coal mine
hazards, as well as those areas within 50 feet of said hazards (RMC 4-3-050). No landslide,
erosion hazard, or coal mine hazard areas have been identified within the vicinity of the BCF
(City of Renton 2020). Based on the Renton critical areas maps, the BCF study area contains
mapped slopes between 15% and 25%, sensitive slopes (25% - 40%), and protected slopes
(>40%). Much of downtown Renton and the Cedar River are mapped as a seismic hazard area,
including the stretch of the river on which the BCF resides (City of Renton 2020). Components
of the proposed BCF do not appear to be subject to the development and alteration standards
for geologic hazards areas, and, therefore, geologic hazards will not be discussed further in this
report. For a map of geological hazard areas, please see Appendix A.
4.0 PROJECT DESCRIPTION
This section describes the proposed project including project element details, construction
methods and sequencing, and best management practices (BMPs).
The proposed action would construct a new removable BCF with specific operational features
that were not included in the original 2008 informal consultation on the BCF. The proposed
action is composed of the following elements:
Replacement of the existing BCF rail system with a permanent channel-spanning
concrete sill foundation approximately 20 feet upstream of the existing weir alignment,
embedded in the channel of the Cedar River;
An improved weir system composed of 13 aluminum picket weir panels;
An integrated electric picket weir lift system operated from shore and capable of raising
and lowering each zone of picket panels independently;
An improved in-stream trap chute and box system that would increase operational
efficiency, improve worker safety, and provide access under a broader range of flow
conditions; and
Civil site improvements for site access, grading, and erosion and sediment control.
Long-term operation of the BCF for fish collection.
The shift in weir location is needed to accommodate the two construction seasons required to
construct the replacement BCF. Building the weir upstream allows the existing BCF to be
operated in its existing location between the two construction seasons, while avoiding
interference with components of the replacement BCF.
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The replacement BCF would consist of aluminum panels mounted to an aluminum subframe
that would be rotated off a concrete sill into a raised position by extending a linear actuator
connected to the sill. In the raised position, the extended linear actuator would hold the
downstream end of the picket panels out of the water to establish the weir. When the linear
actuator is retracted, the panels would rotate down to a resting position that follows the
downstream slope of the sill to allow debris to wash off. The new facility would also include
modifications to the existing trap box and perimeter access walkway. The upgraded trap box
would feature a false floor (brail) that can be raised by a hand winch close to the perimeter
access walkway. As the trap floor rises, fish crowd into an accessible trough in the floor
allowing operators to net fish without entering the water or trap. The walkway would provide
safe access to the trap box at high flows, keeping the facility fishable up to 1,000 cfs.
The benefits of the proposed action over the existing system are as follows:
Ability to operate and safely access under a broader range of flow conditions;
Increased attraction flows, improving capture efficiency and reducing risk of migration
delay;
Improved worker access and operational safety, reducing holding and handling time for
target and nontarget species;
Improved weir panel designs to avoid impingement risk;
Electrically operated panel system that can be raised and lowered on demand for
volitional passage and debris management; and
Robust design that can withstand high flow conditions and pass debris and bedload
when lowered, increasing flexibility to respond to unanticipated events.
The replacement BCF includes several improvements to increase fish collection capabilities. It
has been designed to operate in higher-velocity river flows, which allows the BCF to function
later into the year and provides a greater duration for fish collection and increased fish genetic
diversity relative to the current BCF. The existing BCF also does not effectively guide fish into
the trap, given that the trap box is not in the thalweg. This is inefficient for fish collection and
may risk delay in upstream migration of all anadromous fish as they hold below the weir. The
proposed BCF would focus stream flows that would be leveraged to direct fish into the trap.
The replacement BCF would be operated by an electronic actuator lift system that can raise and
lower the picket panels. Each zone of picket panels can be raised or lowered independently
from the rest of the picket panels. This allows panels to be lowered for cleaning, which would
keep the replacement BCF operational.
The proposed BCF increases personnel safety by reducing the need for in-water access and
maintenance. The picket panels can be remotely lowered/raised for cleaning from an upland
area along the southern shoreline, reducing the need for in-water work by personnel to remove
debris. The existing BCF often requires personnel to wade into the Cedar River to access the
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trap box and to conduct maintenance on the picket panels. The new trap box has a walkway
and gangway system to facilitate access to the trap box for fish collection during flows up to
1,000 cfs.
The proposed BCF also provides improved installation and removal processes. The replacement
BCF includes a permanent concrete sill, to which the weir panels can easily attach/detach. At the
end of the collection season, the picket panels and subframes would be lowered and left in the
Cedar River. Annual removal of the picket panels would occur in early July, at lower river
flows. Currently, the existing BCF is manually removed in flow conditions at or approaching
500 cfs.
4.1 Project Elements
4.1.1 Concrete Sill
The existing steel rail fixed to the channel bed would be removed and replaced with a
permanent concrete sill foundation that would be embedded in the riverbed. The concrete sill
would provide the foundation for the picket panel weir. The sill would measure approximately
84 feet long by 21 feet wide by 5 feet deep, spanning the channel from the face of the existing
right-bank retaining wall to the face of the new access ramp (Sheet CS101, Appendix B).
The concrete sill would consist of a 21-foot-wide (measured along the flow direction) reinforced
concrete slab tied to vertical cut-off walls at the upstream and downstream edges which would
protect the sill from potential undermining due to scour as well as provide anchorage and
stability against sliding, uplift and overturning forces imposed on the weir. The upstream edge
of the sill would have a 10-inch-wide by 14-inch-tall curb which would protect the leading edge
of the picket panel and subframe assemblies from debris and allow the assemblies to stand at
least 8 inches clear of the sill to avoid injury to fish when lowering the panels (Sheet CS206,
Appendix B).
The exposed surface of the sill would be sloped from a high point behind the upstream curb to a
low point at the downstream edge of the sill. The sill would slope in profile toward a flat 6-foot-
wide low segment aligned with the trap chute panel from high points at the right and left bank.
This slightly concave design would create a thalweg toward the middle of the river, thereby
promoting attraction flow through the trap facility and guiding the fish to the entrance of the
trap box for collection (Sheet S-202, Appendix B). The curb on the upstream edge of the sill
would be omitted for a 3-foot-wide opening aligned with the low segment to facilitate fish
passage through the trap chute. Boulders would be placed directly upstream and downstream
of this concrete sill to armor the edges and prevent scour (Sheet CS10s and CS206, Appendix B).
An 18-inch-wide, 10-inch-deep utility trench with a removable cover would be provided across
the entire length of the sill to accommodate electrical components and wiring for the linear
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actuators. The sill would contain miscellaneous embedded stainless steel elements to provide
connection points for the linear actuators and the picket weir subframe assembly described
below. An ultra-high-molecular-weight pad, or similar, would also be provided on the sill to
ensure that the aluminum subframe members do not rest directly on concrete.
The weight and foundation embedment of the concrete sill is proportioned to achieve safety
factors recommended by the Corps for global stability against sliding, flotation (or uplift), and
overturning load effects imposed on the weir under an operational failure condition where the
panels become entirely clogged during the maximum operational flow. Vertical cutoff walls
would be provided at all exposed edges of the sill to protect against scour with the added
benefit of mobilizing passive resistance against global sliding forces. The concrete sill would
also be capable of supporting the weir during operation, including resistance to point loads
imposed by each linear actuator and the hinged panel subframe assemblies. While the concrete
sill is sloped to promote debris removal and sediment transport across the facility, it is
recognized that the river is aggrading, and substrate materials may consequently accumulate on
the sill and prevent free rotation of the subframe and/or linear actuators during the operational
period.
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Figure 2. Proposed Site Plan Drawings Showing Project Elements
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4.1.2 Picket Weir
The improved picket weir system would consist of removeable picket panels mounted to an
aluminum tube subframe (Sheets S-101, S-104 ad S-105, Appendix B). The aluminum subframe
would anchor to a gusset plate on the curb on the upstream edge of the concrete sill. These
aluminum picket panels are designed to meet NMFS standards for fish passage barrier systems
(NMFS 2011). The picket panels would be approximately 3 feet wide by 20 feet long and
composed of 1-inch outside-diameter aluminum tubing at 1-inch clear spacing. Adjacent pickets
would be connected in panels by horizontal stringers at intermittent spacing not exceeding 5
feet along the length of each panel. The panel width ensures that clear spacing between pairs of
picket panels would not exceed 1 inch. Each panel subframe would be connected to a linear
actuator so panels can be raised or lowered in zones to allow Chinook salmon passage or
cleaning of individual sections of the weir.
Picket weir assemblies would be raised and lowered by the linear actuator system, as described
in Section 4.1.2. In the raised position, the pickets would be oriented approximately 7 degrees
above horizontal to achieve the 1-foot-per-second NMFS criterion for maximum flow velocity
across the wetted area of the weir. This configuration closely matches the orientation of the
pickets during operating conditions of the existing facility. In the lowered position, the pickets
would be oriented approximately 4 degrees below horizontal before the subframe contacts the
concrete sill.
A standalone, non-operable trap chute panel assembly would exist on the flat 6-foot portion of
the concrete sill to allow upstream fish passage through the weir and into the trap box (Sheet S-
208, Appendix B). This trap chute panel assembly would have a tube frame and supports that
would seat into blockouts in the concrete sill. Along the entire length of the trap chute, the
inside width would be 36 inches clear and the inside height would be 36 inches clear. To
maintain the 36-inch clear height inside the trap chute, the top of the trap chute would slope
upstream similarly to the concrete sill. The pickets downstream of the trap chute, as well as the
pickets adjacent to the trap chute, would be the same length and orientation as the pickets on a
typical picket panel to ensure alignment with adjacent picket weir assemblies. The overall width
of the trap chute panel assembly would be 71 inches to ensure that clear spacing between panels
would not exceed 1 inch.
4.1.3 Picket Lift System
The electric lift system to raise and lower the picket weir would consist of electric cylinders,
communication and power cabling, a water-tight controls enclosure called a pressure vessel,
and a controls enclosure on the left-bank (Sheet E-101, Appendix B). The electric actuators
would be mounted to the top of the concrete sill and the upper cross bar of the picket subframe
assembly. When actuated, a single electric actuator would raise or lower a single subframe
assembly and associated picket panels (Sheet S-203, Appendix B). Communication and power
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supply for each actuator would be provided by flexible cabling that routes from each actuator
through a cabling trench in the top of the concrete sill. The cabling trench would house rigid
conduit with cabling splits for the flexible branch line connections to the actuators.
The system would be designed to operate independent subsections or “zones” of the weir at a
given time. When debris accumulates against the pickets, only the section(s) of the weir needing
to be cleaned would be lowered, instead of dropping the entire barrier. This also allows the
power supply to the actuators to be smaller, because it would be required to operate fewer
actuators at a time.
4.1.4 Improved Trap Box Assembly
The existing BCF trap box and perimeter access walkway would be replaced to provide
increased worker safety and operational efficiency over a broader range of flow conditions. A
new shore-to-trap aluminum gangway would provide safe access to the trap up to 1,000 cfs
flow levels.
The installed trap box would measure 15 feet long by 6 feet wide (10 feet wide if including the
removable walkway) by 7.5 feet tall, and it would consist of an aluminum square tube frame
with integral vertical pickets and porosity plates. Except for the upstream side, the trap box
would have a grated, aluminum, removable access walkway for operations personnel around
the remaining perimeter. The top surface of the walkway would stand at 4 feet from the
riverbed, with the walkway approximately 3 to 4 inches above the maximum operational water
surface elevation to enable collection activities during high flows. This perimeter walkway
would be accessed from the river bank by an approximately 30-foot-long by 2-foot-wide
prefabricated, removable aluminum gangway that spans from the boat ramp to the trap. This
gangway would be supported by T-bars. The walkway access would be gated and signed to
prevent public usage (Sheets S-106 and S-201, Appendix B).
The trap box would feature a central brail floor which would be raised and lowered by a hand-
operated winch to facilitate fish retrieval without entering the river or the trap (Sheets M-207
and M-208, Appendix B). As the floor is lifted, fish in the trap would be centralized within a
neoprene trough for collection. To accommodate fish collection, hinged panels on the trap sides
would swing down when the trap is being emptied so operators would not have to reach over
the full height of the sides.
The downstream end of the trap box would be a diversion area that leads from the trap chute to
the larger trap box area (Sheet S-208, Appendix B). The diversion area would be a picketed,
rectangular aluminum frame structure 5 feet long and 3 feet wide (inside) to match the trap
chute, and 4 feet high to match the trap box walkway. The upstream end of the diversion area
would contain a PVC picket assembly similar to what is used by WDFW in the existing facility.
This assembly, referred to as the “chime gate,” would be formed with an aluminum beam
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spanning the diversion area supporting a curtain of PVC pickets or “chimes.” This would be
similar to the existing BCF assembly. The chimes gate is pinned at the top to the support beam
and would hang at a slight angle across the diversion box, resting against a bottom cross-frame
tube of the trap box. This configuration allows migrating fish to push the pickets open as they
swim upstream and then close once the fish have entered the trap box.
On one side (e.g., left bank) of the diversion area would be a hand-operated, lifting trap bypass
gate that can be raised to allow non-targeted fish, such as Chinook salmon, to bypass the trap
box and continue swimming upstream. This gate would be paired with a second removable
gate of similar configuration just downstream of the chime gate to ensure that non-targeted fish
exit through the trap bypass gate. During normal operation, the trap bypass gate would be
closed and the chime gate would be removed. A third gate that separates the trap area from the
diversion area, called the trap entrance gate, would be open during normal operation.
The brail floor of the trap box would have rectangular aluminum tubing for a frame and
aluminum circular tubing pickets would run across the floor at a 2-inch spacing except for the
downstream end which would house a neoprene sheet that would fold up flat when the floor is
lowered but would create a trough when the floor is raised (Sheet S-212, Appendix B). The rest
of the brail floor would slope slightly down towards this trough, with the upstream end of the
floor 6 inches higher than the downstream end. As the floor is lifted, fish would slip down the
slope into the trough so operators can net them from the downstream side of the box. The floor
would be stable and sturdy enough to support one operator entering the trap box and standing
on it in the raised position if necessary. Operator entry into the trap box is facilitated by a 2-foot
wide opening and hinged access gate on the right bank side of the upstream end of the trap box.
To provide cover for fish in the trap and accommodate fish collection, the trap box would have
perforated aluminum lid sections that either fold, accordion, or slide. The lid would be 3.5 feet
above the surface of the walkway. When open, the lid would rest on the upstream end of the
trap box to allow full operator access to the neoprene trough where the fish would be crowded.
Depending on the final lid option selected, up to 90% of the lid area would be open. If needed,
the portion that would not be open would be easily accessible through the south access
opening.
As stream flows decrease and the water level drops, the number of fish the trap box can support
decreases due to the reduced volume. Holding criteria for an “in-stream” holding box is not
specifically identified in the NMFS criteria. The flows considered for this design range from a
depth of 1.25 feet, which provides minimal depth at the trap entrance, to a depth of 3.75 feet
corresponding to 1,000 cfs of flow. A curve has been developed that illustrates water depth vs.
number of fish held based on NMFS criteria (Appendix B). This would provide operator
guidance for when the trap box is considered “full” and the fish should be transported to the
Hatchery.
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Two debris deflector panels with vertical picket bars would be placed upstream of the trap box
to protect the trap box and trap chute from debris impact. Debris that encounters the deflector
panels would be redirected away from the trap box toward the downstream picket panels.
These panels would be 7.5 feet long by 6 feet tall and would be similar to the panels at the
existing facility. The picket size and spacing of these panels would match the trap box. The
height of these panels exceeds the maximum operation flow level. The design, installation, and
removal of the proposed debris deflector panel is consistent with the debris deflector panels
used to protect the existing BCF.
Like the current BCF design, the trap box would be installed and removed using a crane
operating from the paved shoreline access point. The trap would be placed behind the trap
chute and connected to the entry. The access gangway would allow BCF crew to access the trap
walkway from shore.
Attraction flow created by the new trap facility would also be improved. The goal of these
improvements is to reduce the flow inside the trap while also increasing the flow through the
trap chute to attract fish to the trap. This flow-shift prevents fish from being delayed by the weir
without entering the trap and reduces the strain on fish while in the trap. On the upstream face
of the trap box would be a perforated plate with 20% open area to reduce the amount of flow
directly through the box providing a quiescent zone in the box (Sheet S-215, Appendix B). Water
would seep through these panels before entering the trap. Because the front face of these panels
would not form a tight seal with the streambed, some water would pass below them and up
through the pickets along the bottom of the box. This would create enough flow to concentrate
fish at the upstream end without tiring them out. The sides of the trap box would also be
perforated plate with 20% open area for the first 6 feet upstream. This results in reduced
velocities in most of the trap. There would be pickets along the remaining 6 feet on the
downstream end of the sides to allow water in. When the perforated plates become covered in
smaller debris, operators would clean the plates from the walkway.
4.1.5 Civil Site Improvements
Civil site improvements include access improvements to the south side of the collection facility.
These upland components of the project proposal are limited to features needed to facilitate
installation and removal of the BCF each year and to operate the BCF when it is in the river. The
access road to the boat ramp would be widened by 3 feet to the north to accommodate a larger
crane truck needed for installation of the new BCF. A portion of the existing boat ramp would
be demolished and the new boat ramp would be relocated approximately 20 feet upstream of its
current location to be in line with the new concrete sill. This would require approximately 1,148
square feet of new concrete on the boat ramp’s eastern edge, 170 square feet of which would be
below the ordinary high water mark (OHWM). A pad composed of permeable void structure,
grass-filled concrete pavers would be established adjacent to the east side of the boat ramp to
provide a level pad for the new trap walkway and to anchor and to support crane outriggers;
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the permeable paver pad would be 86 square feet in size, 35 square feet of which would be
located below the OHWM. The hammer head section of the boat ramp would also be extended
upstream with permeable pavers to improve the turning radius. The area where the boat ramp
is removed would be restored with native vegetation (Sheet CS101 in Appendix B).
Scour protection would be included on the upstream and downstream sides of the new concrete
sill. Riprap with a D50 of 8.3 inches would be placed to a depth of 4 feet (Sheet CS 206,
Appendix B) and would extend 8 feet in the upstream and downstream directions from the sill
margins (Sheet CS106, Appendix B). A concrete retaining wall along the waterward edge of the
boat ramp and extending upstream to protect the new boat ramp and the permeable pavers
from scour. The retaining wall would begin approximately 3- to 4-feet below the river bed
(varies along the length of the concrete sill) and transition in height to be flush with the boat
ramp elevation (Sheet CS203, Appendix B). The retaining wall would transition into a wing wall
that would extend approximately 9 feet upstream of the boat ramp. This would provide
additional scour protection for the boat ramp and would offer support for the permeable paver
pad immediately upland, as well as providing a supporting structure for the gangway that
allows operator access to the trap box.
Other upland improvements include the installation of a new light pole, which would be
located directly east of the new boat ramp. The light would only be used during emergencies or
to improve safety during operations at dark. A control panel for the electronic actuators and
picket gate lift system, as described in Section 4.1.3, would be affixed to this light pole.
4.2 Construction
The construction activities associated with the proposed action include:
Cofferdam installation and removal;
Foundation and sill installation;
Electronic actuator conduit installation;
Electronic actuator control system construction;
Boat ramp widening construction; and
Boat ramp key wall installation.
The weir panels and trap improvements would be fabricated off-site by a commercial vendor
and transported to the site by truck. These features would be installed and tested during project
construction for troubleshooting. Once construction is complete, the annual installation and
removal of the weir and trap system is considered part of normal BCF operations, which were
consulted on previously.
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4.2.1 Construction Schedule and Phasing
The current schedule anticipates final project design in August 2021 and construction
commencing in 2022. Project construction would occur in 2 phases, with Phase 1 in 2022, and
Phase 2 in 2023. In-water work would occur primarily during the agency-approved work
window each year, which extends from July 1 to August 31 (Corps 2010). However, a 1-month
extension to the work window would be requested, with work beginning June 1. Upland work
would not be confined to the work window but is generally expected to coincide with in-water
activities or be phased just before and after.
Phase 1 consists of all work on the south side of the Cedar River, which includes all upland
work and construction of approximately half of the concrete sill, extending from the south bank
to just past mid-channel. Phase 2 includes in-water construction of the north half of the concrete
sill, facilitated from Cedar River Park on the north bank. The in-water construction methods as
described in Section 4.2.3 would be used for both phases of work.
The two construction phases are necessary because the replacement facility cannot be
constructed in a single in-water work season. SPU would attempt to incentivize the contractor
to complete construction in one year to minimize overall project impacts.
Phase 1 Staging/Laydown Areas, Site Preparation, and Upland Development
Phase 1 staging, laydown, and upland development would occur in 2022. Project construction
would begin with the establishment of staging areas and overall site preparation. The primary
staging/laydown area would be established in the existing Cedar River Trailhead parking lot,
approximately 100 feet from the OHWM. A majority of staging/laydown, including a concrete
washout area, would occur in this delineated area. When construction shifts from the south
bank to the north bank in 2023, a second staging/laydown area would be established on the
north bank.
For Phase 1, once the contractor staging/laydown area is established, focused site clearing
would begin along the shoreline. During this stage of construction, the project’s temporary
erosion and sedimentation control (TESC) plan measures would be installed (Sheet C-101,
Appendix B). Clearing would be limited to the minimum necessary to support construction.
Approximately 3,950 square feet of riparian area would be cleared to accommodate the upland
civil improvements. Site clearing and preparation work would be completed using a
combination of heavy equipment (e.g., excavators, loaders) and hand-operated power tools.
During this phase of work, the existing access road would be widened by 3 feet. The existing
boat ramp would be partially demolished and the new portion of the ramp would be
constructed to align with the new concrete sill (Sheet CD-101, Appendix B). Permeable pavers
would be installed to construct the hammerhead at the top of the boat ramp, and the permeable
paver pad would be constructed at the shoreline to support fish trap access and crane
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outriggers. Permeable pavers are proposed in these areas to minimize impervious surface, while
still achieving design goals for project facilities that support the replacement BCF. Overall, the
proposed new hardscaping would encompass approximately 1,564 square feet of access road
and boat ramp and 414 square feet of permeable pavers, approximately 45 square feet of which
is below the delineated OHWM. A total of 654 square feet of the existing boat ramp would be
removed (539 square feet below OHWM), for a net increase of approximately 1,324 square feet
of hardscaping. During Phase 1, approximately 1,316 square feet of additional riparian area
would be temporarily disturbed.
In total, approximately 150 cubic yards (cy) of excavation and 190 cy of fill would be required to
complete this upland work.
Other ancillary upland improvements include installation of one light pole and trenching for
placement of electrical conduit.
4.2.2 Phase 2 Staging/Laydown Areas
Phase 2 staging and laydown work would occur in 2023 and would be limited to the north bank
and accessed from Cedar River Park. Staging would be established along the north bank
beneath the I-405 bridge, pending approval from the Washington State Department of
Transportation (WSDOT) and coordination with the City of Renton. Staging/laydown areas
would be fenced to demarcate the area, and traffic controls and other signage would be
installed. No vegetation clearing is necessary for Phase 2 staging and laydown work.
A smaller work area would be established immediately upland of the Phase 2 cofferdam to
facilitate construction. The existing informational kiosk would be temporarily relocated, and the
area would be demarcated from public access with fencing. Steel plates would be laid in the
work area to protect existing turf. The work area would allow a mobile crane and other
equipment to access the interior of the cofferdam from the Park; the rock retaining wall adjacent
to the Cedar River would be protected. Once construction of Phase 2 is complete, the site would
be restored to preconstruction conditions.
4.2.3 In-Water Work
In-water work for both phases would use the same sequence and construction elements. Prior
to in-water work, a dewatering system would be installed to isolate the work zone such that all
work below the OHWMs of the Cedar River is conducted in a work zone free from water. Final
dewatering methods would depend on the system selected by the contractor. Prior to the start
of any in-water operations, the contractor would be required to submit for SPU approval a
dewatering plan that includes cofferdam and dewatering design and equipment, safety
procedures, sequence of construction, and re-watering procedures. A cofferdam is a temporary,
watertight structure erected around a construction site designed to keep water from inundating
the site during construction.
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The contractor would be required to furnish, install, maintain, and operate all necessary
pumping and other equipment necessary to remove all storm, subsurface, and cofferdam
leakage waters that may accumulate in the cofferdam interior. All dewatering equipment would
be required to be maintained and operated at the efficiency and capacity necessary for
maintaining the cofferdam interior free from standing water or wet conditions that prevent
proper construction.
The contractor would be required to provide dewatering facilities with stand-by pumps having
100 percent standby capacity. All dewatering pumps and their prime movers would be fitted
with mufflers, noise-control enclosures, or other noise control methods, measures, and features
such that steady noise emanating from this equipment does not exceed the permissible sound
levels defined in the local noise ordinance. Dewatering of all excavation areas and disposal of
all water handled would be in compliance with all applicable local and state government rules
and regulations.
The contractor would be required to remove the dewatering system in a manner that allows
allow groundwater elevations to slowly return to natural elevations and to slowly flood the
dewatered area to establish water surface elevations upstream of the work zone and equal to
tailwater downstream of the work zone prior to removal of the temporary cofferdam(s).
The temporary cofferdam is expected to be a PortaDam, AquaBarrier, Bulk-Bag,
ecoblock/sandbag, or sheetpile system, or other similar cofferdam system. The cofferdam
system would be installed (and removed) in 2 phases, with Phase 1 occurring on the south bank
of the Cedar River during the 2022 in-water work window and Phase 2 occurring on the north
bank of the Cedar River during the 2023 in-water work window. The cofferdam would extend
to just beyond the middle of the river; this allows river flow and unimpeded fish passage
during construction. It would take approximately 1 to 1.5 weeks to install the cofferdam, per
phase. Construction equipment required for cofferdam installation is anticipated to include a
hydraulic excavator, a loader/forklift, and a mobile crane. If sheetpile is used, and vibratory pile
driver rather than an impact driver would be required for pile installation.
After the cofferdam is complete and the river diversion is stabilized, the area behind the
cofferdam would be completely dewatered. Pumps with intake hoses fitted with fish-compliant
screening would be installed into the low points of remaining inundated areas. Outlet hoses
would be routed to a point downstream of work activities back into the Cedar River. The pools
would then be dewatered at a maximum rate of 2 inches per hour, allowing aquatic life to
migrate with the receding water level, thereby preventing stranding. Capture and release of any
fish, or other remaining aquatic life, back into the natural flow of the Cedar River would be
completed by qualified personnel pursuant to WSDOT’s Fish Exclusion Protocols and
Standards (WSDOT 2016).
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Using pumps, continuous dewatering via pumps would be required during construction to
keep the work area dry. Turbid water would not be discharged to the Cedar River. Instead, it
would be contained, settled, and discharged to a suitable upland location allowing infiltration.
A visual monitoring program would be established and approved prior to construction to
protect water quality and to ensure approval of an appropriate discharge method. Any water
that has come into contact with cementitious material would be considered process water and
would be either treated before discharge or disposed of off-site. However, the dewatering
system would be designed to minimize comingling of water and cementitious material, through
a sump located within the cofferdam to divert water, or other similar methods. The work within
the cofferdams is anticipated to take approximately 2 to 3 months per phase.
Following isolation of the work zone and initial dewatering, work on the permanent concrete
sill would begin. Excavation for the concrete sill would be completed using a hydraulic
excavator. The area would be excavated to a desired subgrade depth, with 1 foot of over-
excavation. Some excavated material would be retained for backfill, but approximately 100 cy of
material would be permanently removed from the river channel and taken off-site for disposal.
Once excavation is complete, compacting equipment (e.g., a small roller) would be used to
compact the riverbed. Geotextile and road-base aggregate would then be placed in the footprint
of the excavation. After placement of the road-base aggregate, concrete would be poured
directly on grade to create the permanent sill, with forms constructed along the sidewalls. The
concrete sill would be constructed in 2 phases, consistent with the phased construction
approach. Once the concrete sill has cured to appropriate strength, boulders would be placed
directly upstream and downstream of the sill to prevent scour.
Electrical systems for the new weir would be installed and affixed to the sill and the trench after
approximately 1 week of curing. Installation of the electrical system would also be subject to the
phased construction approach. This work requires use of a forklift, mobile crane, small diesel
generators, air compressor, and hand tools.
A cast-in-place concrete retaining wall would be constructed along the base of the boat ramp
during the Phase 1 construction. The wall would extend approximately 3- to 4-feet below the
grade of the existing river bed, functioning as a key wall to prevent scour. As the wall extends
farther upstream, it would transition to a height flush with the boat ramp. This section of the
wall would provide further scour protection for the boat ramp and support for the permeable
paver pad immediately upland. Boulders would be placed upstream and downstream of the
concrete retaining wall for further scour protection.
Total grading quantities for in-water work include excavation of approximately 760 cy of native
sediment and approximately 775 cy of fill (e.g., concrete, aggregates, boulders). Once in-water
work is complete, the cofferdam would be slowly re-flooded to prevent scour. Pumps would
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then be removed from the work area to allow water to fill the cofferdam cell. Lastly, the
cofferdam would then be removed from the river and uninterrupted river flow would resume.
4.2.4 Upland Work
Upland construction activities include continuation of the electrical conduit to connect the
electronic actuators to a control panel, demolition and reconstruction of the boat ramp, and
widening of the access road. This would require removal of existing concrete surfaces, trenching
and excavation, and concrete pouring. Work would include removal of 654 square feet of
existing ramp area, with 539 square feet of that existing ramp occurring below OHWM. The
area of new proposed boat ramp would include 1,145 square feet of concrete, 191 square feet of
which would extend below the OHWM. Additionally, the access road widening would include
the addition of 419 square feet of concrete in the upland area. Two areas of permeable pavers
would be installed to the east of the new boat ramp over 414 square feet, with approximately 45
square feet of the permeable pavers and a stabilization wing wall occurring below OHWM.
One mature black cottonwood (Populus trichocarpa) tree would be removed to accommodate the
boat launch construction. All excavation would be backfilled with native material, and any
remaining overburden would be removed from the site for disposal at a permitted commercial
facility. Disturbed surfaces would be restored and/or repaved to the existing condition.
4.3 Best Management Practices
BMPs would be implemented throughout construction to minimize potential temporary
impacts. Though specific implementation means and methods would be determined by
construction contractors, the following BMPs are proposed for the project’s construction
contract documents:
BMPs for general impact avoidance and minimization:
Construction impacts would be confined to the minimum area necessary to complete the
project.
Boundaries of clearing limits would be clearly flagged to prevent disturbance outside of
the limits.
Removal of riparian vegetation would be minimized, and riparian vegetation would be
replanted where possible.
Vegetation would be grubbed only from areas undergoing permanent alteration. No
grubbing would occur in areas slated for temporary impacts.
All construction activities would comply with water quality standards set forth in the
State of Washington Surface Water Quality Standards (Washington Administrative
Code [WAC] 173-201A).
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All construction activities would comply with conditions of applicable Department of
the Army (Corps) permit, Washington State Department of Ecology) Water Quality
Certification, and WDFW Hydraulic Project Approval.
BMPs to reduce the risk of delivering sediment to waterbodies:
A TESC plan would be developed and implemented for all project elements that entail
clearing, vegetation removal, grading, ditching, filling, embankment compaction, or
excavation. The BMPs in the plan would be used to control sediment from all vegetation
removal and ground-disturbing activities. Examples of applicable BMPs include silt
fences, wattle, compost socks, ditch check dams, seeding and mulching, stabilized
construction entrances, and street cleaning.
The contractor would designate at least one employee as the erosion and spill control
lead. This person would be responsible for installing and monitoring erosion control
measures and maintaining spill containment and control equipment. The erosion and
spill control lead would also be responsible for ensuring compliance with all local, state,
and federal erosion and sediment control requirements, including discharge monitoring
reporting for Ecology.
Erosion and sedimentation control devices would be installed, as needed, to protect
surface waters and other sensitive areas. Actual locations would be specified in the field
based upon site conditions.
Project staging and material storage areas would be located a minimum of 150 feet from
surface waters or in currently developed areas such as parking lots or previously
developed sites.
Erodible material that may be temporarily stored for use in project activities would be
covered with plastic or other impervious material during rain events to prevent
sediments from being washed from the storage area to surface waters.
Erosion and sedimentation control BMPs would be inspected after each rainfall and at
least daily during prolonged rainfall. Sediment would be removed as it collects behind
sedimentation control BMPs and prior to their final removal.
All exposed soils would be stabilized during the first available opportunity, and no soils
shall remain exposed for more than 7 days from May 1 to September 30.
All silt fencing and staking would be removed upon soil surface stabilization and project
completion.
Exposed soils would be seeded and covered with straw mulch or an equally effective
BMP after construction is complete.
The project would remove any temporary fills and till-compacted soils, and restore
woody and herbaceous vegetation according to an Engineer-approved restoration or
planting plan.
A minimum 1-year plant establishment plan would be implemented to ensure survival,
or replacement, of vegetation by stem count at the end of 1 year.
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BMPs to reduce the risk of introducing pollutants to waterbodies:
The contractor would prepare a Spill Prevention, Control, and Countermeasure Plan
(SPCC) plan prior to beginning any construction activities. The SPCC plan would
identify the appropriate spill containment materials (which would be available at the
project site at all times), as well as specify what to do and whom to contact when spills
occur. The approved SPCC plan would provide site- and project-specific details
identifying potential sources of pollutants, exposure pathways, spill response protocols,
protocols for routine inspection fueling and maintenance of equipment, preventative
and protective equipment and materials, reporting protocols, and other information
according to contract specifications.
All equipment to be used for construction activities would be cleaned and inspected
prior to arriving at the project site to ensure no potentially hazardous materials are
exposed, no leaks are present, and the equipment is functioning properly. Should a leak
be detected on heavy equipment used for the project, the equipment would be
immediately removed from areas within or immediately adjacent to the OHWM of
waterbodies.
For construction access, a stabilized construction entrance, temporary access roads pads,
and street cleaning would be provided.
Absorbent materials would be placed under all vehicles and equipment on construction
access or demolition laydown pads, or other over-water structures. Absorbent materials
would be applied immediately on small spills and promptly removed and disposed of
properly. An adequate supply of spill cleanup materials, such as absorbent materials,
would be maintained and available on-site.
A concrete truck chute cleanout area or equally effective BMP would be established to
properly contain wet concrete.
Uncured concrete and/or concrete byproducts would be prevented from coming in
contact with streams or water conveyed directly to streams during construction in
accordance with WAC 220-110-270(3).
Excavated material would be removed to a location that would prevent its re-entry into
waters of the state.
As practicable, the contractor would fuel and maintain all equipment more than 200 feet
from the nearest wetland, drainage ditch, or surface waterbody, or in currently
developed areas such as parking lots or managed areas. Commercial facilities that
provide such services, for example gas stations, are excluded.
Materials disposal would occur at contractor-provided disposal sites and in accordance
with federal, state, and local laws and ordinances. Additionally, the contract may
contain special conditions and requirements that pertain to the demolition and disposal
of specific structures or to working in specific areas.
BMPs for in-channel construction:
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All work below the OHWM would be completed during the approved in-water work
window, and would fully comply with all environmental permits and other
authorizations.
The work would follow WDFW’s Level 1 Decontamination Protocols for invasive
species management (WDFW 2012).
To minimize fish handling, fish would be herded out of and excluded from re-entering
the cofferdam area before its completion.
Before, during, and immediately after isolation and dewatering of the in-water work
area, fish from the isolated area would be captured and released using methods that
minimize the risk of fish injury, in accordance with the WSDOT protocols for such
activities (WSDOT 2016).
Cedar River flows would be monitored throughout construction using the USGS gage
12119000 (Cedar River at Renton) upstream of the project site. During flow events
approaching the 2-year discharge, equipment and materials would be moved off the
access pads until waters subside.
4.4 Operations and Maintenance
Excluding the permanent concrete sill, all operable components of the replacement BCF would
be installed/removed annually. Installation of all the BCF components would occur in early
September and removal would occur in December, except for the picket panels, which would be
left in a lowered position against the concrete sill for removal before early July. Between
December and July, maintenance may occur on an up-to-weekly basis to remove bedload that
would accumulate on the picket panels and concrete sill. This would require raising the picket
panels a few inches off the lowered position to dislodge accumulated sediment and debris.
Recurring maintenance at this frequency would substantially reduce the amount of clearing
required before the pickets are removed each summer and before their installation each
September. Cleaning twice yearly, before picket removal in July and prior to installation in
September, would be the minimum necessary maintenance of accumulated bedload. In these
events, the bedload could be cleared manually with a shovel or similar tool, with an airburst-
type system, and/or with a combination of raising and lowering the pickets.
Once the sill is cleared of sediment, the picket panels would be mounted to the upstream face of
a subframe connected to the concrete sill. This process includes installation of a central trap
chute. Once the picket panel weir assembly is in place, pneumatically driven T-bars would be
installed in the streambed to support the chute and trap box assembly. The trap box debris
deflector panels would be installed by crane. The temporary detachable gangway would be
installed to provide access to the trap box. Annual installation/removal of the BCF, including
equipment staging, would be conducted from the boat ramp on the south bank.
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During operation, the electronic actuator lift system would lift or lower the picket panel weir
from an upland control area on the south bank. When the weir is raised in an operating ‘up’
position,, fish would be collected in the trap box until the fish capacity for the measured water
depth is reached or when maximum holding times are reached, and fish must be removed.
Refer to Section 4.1.4 and Appendix B for more detail on holding times and NMFS-provided
criteria. Fish handling, including removal or release from the trap box, and transport to the
Hatchery would meet NMFS-provided criteria and would not change from existing operations.
The weir may be lowered to allow Chinook salmon passage or for cleaning.
5.0 IMPACT ASSESSMENT
This section discusses impacts to critical areas and shoreline ecological functions and processes
present in the study area. The project would involve both unavoidable temporary and
permanent impacts. For the purposes of this impact assessment, the combined HCA and
shoreline environment impacts would be quantified specific to the Cedar River (aquatic
shoreline habitat below the OHWM) and the riparian buffer (shoreland) within the construction
limits.
5.1 Avoidance and Minimization of Impacts
SPU has designed the project to minimize the permanent and temporary impacts of the project
while still meeting the project’s engineering standards and design criteria. With a project of this
nature, minimizing the scope of construction and operational elements are prioritized to reduce
costs, in addition to reducing impacts to the natural environment.
In addition to the BMPs addressed in Section 4.3, the following measures have been
implemented to avoid or minimize impacts to the site:
The sill has been designed to the minimum size necessary to meet the engineering
criteria.
The boat ramp reconfiguration and crane pad siting has reduced the number of trees to
be removed from 3 to 1.
The access road would be widened only the minimum amount necessary to
accommodate the necessary equipment for the BCF installation.
The crane pads and turning area would be constructed using permeable pavers to
minimize impervious surfaces and promote infiltration.
5.2 Temporary Impacts
Construction activities would result in unavoidable temporary impacts to both the Cedar River
and the riparian buffer (Figure 3). Table 1 summarizes the temporary impacts from the project.
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Figure 3. Temporary Unavoidable Project Impacts
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Table 1. Summary of Temporary Impacts
Impact Type Project Element Impact Area (square feet)
Dewatering Cofferdams Year 1: 6,228
Year 2: 3,495
Streambed Excavation Sill Construction 1,586
Riparian Clearing Civil Improvement
Construction Limits 3,733
Notes: Temporary impacts would be restored in-kind.
5.2.1 Cedar River Temporary Impacts
Construction activities would require temporarily installing sequential cofferdams, on first the
south bank and then the north bank per the project phasing. This would divert the Cedar River
while allowing for full fish passage, and the dammed portion would be dewatered to allow sill
construction. Cofferdam dewatering would impact 6,228 square feet during Year 1 and 3,495
square feet during Year 2. Though isolating the project construction area in the river is a
conservation measure intended to minimize the overall adverse effects to salmonids and
habitat, fish and wildlife species present in the surrounding area at the time of construction
activities would likely be temporarily disturbed and displaced while the cofferdam remains in
place.
Construction of the concrete sill would require the temporary excavation of approximately
1,586 square feet of riverbed outside of the limits of the permanent sill footprint over the 2
construction phases. The temporary excavation limits in the Cedar River would be backfilled
with the scour protection boulders described in Section 4.2.3.
Cofferdam installation, dewatering, and streambed excavation would result in removing and/or
smothering some benthic invertebrates that provide food for salmonids. Effects to aquatic
macroinvertebrates from smothering would be temporary, and the river would return to
natural contours following the completion of construction. Given that this is a depositional
reach of the river, gravels are anticipated to accumulate over the scour protection boulders and
restore the channel bed to conditions typical of the reach. Macroinvertebrates are expected to
rapidly recolonize disturbed areas (within approximately 2 weeks to 2 months) (Merz and Chan
2005, Baumgartner and Robinson 2016, Mackay 1992).
Project construction would disturb the channel bed and may release periodic pulses of sediment
into the water column, resulting in a temporary increase in total suspended solids (TSS) levels.
Elevated TSS is most likely to occur during initial cofferdam placement and subsequent
cofferdam removal and re-watering of the in-water work areas. Pulses may also occur during
periodic pumping of the work area. Elevated TSS levels would be expected to last from less
than 1 hour to potentially 3 hours depending on the activity. TSS monitoring would occur as
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per the Ecology Section 401 Water Quality Certification, which together with other BMPs
described in Section 4.3, would help reduce adverse impacts.
Decreases in dissolved oxygen levels, pH, and unintentional releases of hydraulic fluid from
heavy equipment may occur during construction. However, implementing applicable BMPs
and adherence to in-water work timing restrictions would reduce potential adverse effects from
above-mentioned impact mechanisms.
Overall, temporary impacts to the Cedar River would be restored following construction and
the return to baseline channel conditions is anticipated within the subsequent fall/winter high
flow conditions. No compensatory mitigation is proposed for temporary Cedar River impacts.
5.2.2 Riparian Buffer Temporary Impacts
In order to construct the permanent civil site improvements, including the boat ramp, crane
outrigger Grasscrete pad, the turning area Grasscrete pad, and the access road widening,
clearing limits of 3,733 square feet outside of the permanent infrastructure have been
established. Due to flood damage occurring in February 2020, much of the proposed clearing
limits is unvegetated. Presently, only sparse native shrubs and Himalayan blackberry occurs
within the clearing limits and would be removed. Temporary clearing of native vegetation
within the riparian buffer during construction would be restored at a 1:1 ratio with native
plants appropriate for the setting. Riparian restoration and applicable tree replacement would
be performed in accordance with the provisions of RMC 4-3-090.F and RMC 4-4-130. No
compensatory mitigation is proposed for temporary riparian buffer impacts.
5.3 Permanent Impacts
The completed project would result in unavoidable permanent impacts to the Cedar River and
the riparian buffer (Figure 4). The proposed BCF infrastructure would effectively result in fill
impacts within the Cedar River and hardscaping within the riparian buffer. Table 2 summarizes
the permanent impacts associated with the project.
July 2020 Page 32
Figure 4. Permanent Unavoidable Project Impacts
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Table 2. Summary of Permanent Impacts
Impact Type Project Element Impact Area (square feet)
Cedar River Fill
Boat Ramp 191
Grasscrete Crane Pad/Retaining Wing
Wall
45
Concrete Sill 1,764
Removal of Old Boat Ramp -539
Total Net Fill 1,461
Riparian Buffer Hardscaping
Boat Ramp 954
Grasscrete Crane Pad 52
Grasscrete Turning Area 317
Access Road Widening 419
Removal of Old Boat Ramp -115
Total Net Hardscaping 1,627
5.3.1 Cedar River Permanent Impacts
The project would directly impact the Cedar River bed through the installation of the weir sill
and, to a lesser degree, the associated access structures. The presence of the sill and access
structures would permanently impact approximately 2,000 square feet of benthic habitat.
However, the project would also remove 539 square feet of the existing boat ramp below
ordinary high water, for a net increase in permanent fill of benthic habitat of 1,461 square feet.
The presence of a fixed structure in the channel has the potential to affect sediment dynamics,
reduce benthic habitat productivity, and alter habitat formation/availability.
The water surface and velocity profiles of the proposed weir have been determined using a
HEC-RAS 1-dimensional model. Alteration of sediment dynamics in this reach would largely be
a function of changes in water velocities and resulting sheer stresses on the materials, which
would cause either scour or deposition. The HEC-RAS model indicates that the channel and
weir velocities are within acceptable range to minimize the effects of scour or deposition. The
change in water surface elevations based on the estimated weir discharge coefficient has little
effect on the upstream water surface elevations. This reach of the Cedar River flows in a single
channel through low-amplitude meanders and a gradient of less than 0.3%, resulting in a
depositional reach. The presence of the weir is not expected to measurably affect the episodic
deposition and mobilization of the predominantly medium to fine gravel substrate through this
reach.
The presence of the weir would reduce the long-term production of benthic and epibenthic
macroinvertebrates on which juvenile Chinook salmon and steelhead feed. Given the relatively
small size of the weir, the benthic macroinvertebrate production within the project area overall
is not expected to be discernible and benthic productivity is not considered to be limiting for
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juvenile salmonid production. The amount of forage material available for juvenile salmonids
is, therefore, expected to remain similar to pre-project conditions and should not result in a
significant effect to fish.
The presence of the weir would also reduce the long-term availability of suitable spawning
substrate. As discussed in Section 4, the majority of Chinook salmon and steelhead spawning is
thought to occur upstream of this reach of the Cedar River. Spawning habitat is also not
considered to be limiting on salmonid production. Nevertheless, up to 1,835 square feet of the
stream bed would be precluded from spawning potential.
Additionally, juvenile rearing could occur in any shallow margin habitat throughout the project
reach. The existing boat ramp occupies approximately 20 linear feet of the river bank, whereas
the proposed boat ramp and associated retaining wall would occupy approximately 25 feet of
the riverbank, resulting in only a minor net loss of potential shallow margin habitat.
The unavoidable impacts are proposed to be offset through compensatory mitigation, covered
in Section 6.
5.3.2 Riparian Buffer Permanent Impacts
The project would directly impact the riparian buffer from the civil site improvements and
associated hardscaping. The permanent improvements from the boat ramp reconfiguration,
crane pads and turning areas, and the access road widening would result in the addition of
approximately 1,742 square feet of hardscaping within the riparian area on the south bank.
However, the project would also remove 115 square feet of the existing boat ramp, for a net
increase in permanent riparian hardscaping of 1,627 square feet.
The proposed riparian hardscaping would preclude riparian vegetation growth and increase
the impervious surface quantity in the riparian buffer. The inclusion of Grasscrete pavers would
limit the increase in impervious surface to 495 square feet associated with the boat ramp and
access road improvements.
Ecological functions typically provided by riparian buffers include, among others, erosion
reduction, sediment and pollutant removal, wood recruitment and organic litter
production/trophic support, microclimate influence, screening of adjacent disturbances (e.g.,
noise, light), and habitat maintenance and connectivity. Again, due to the flood damage
described in Section 5.2.2, most of the area proposed for civil improvements is unvegetated.
Presently, 1 large black cottonwood tree and a small clump (approximately 100 square feet) of
Pacific ninebark and Himalayan blackberry would be removed. The proposed impacts would
have a negligible effect on erosion control, sediment and pollutant removal, microclimate
influence, screening, and habitat maintenance and connectivity. The vegetation removal would
have a minor effect on organic litter production, shade, and wood recruitment. Overall, riparian
buffer processes are expected to remain relatively unchanged as a result of the project. The
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unavoidable impacts are proposed to be offset through compensatory mitigation, covered in S
Section 6.
6.0 COMPENSATORY MITIGATION
This section discusses the applicable regulations to offset the ecological loss to HCAs and
shoreline environments and the proposed compensatory mitigation strategy.
6.1 Applicable Regulations
As described in Section 3, the regulated resources at the BCF site subject to mitigation include
the HCA and shoreline environment consisting of the Cedar River and its riparian buffer.
Alterations to HCAs require mitigation pursuant to RMC 4-3-050.G.6, which states:
The Administrator may approve mitigation to compensate for adverse impacts of a
development proposal to habitat conservation areas through use of a federally and/or
state certified mitigation bank or in-lieu fee program.
Because the Cedar River is shoreline of the state (Type S water), work within the river and the
riparian corridor is regulated under Renton’s SMP (RMC 4-3-090) as opposed to typical stream
development and mitigation standards under the critical areas regulations (RMC 4-3-050).
Additionally, land adjacent to the Cedar River in the Natural or Urban Conservancy
environment is considered a Class 1 Fish Habitat Conservation Area subject to the provisions of
the SMP (RMC 4-3-090.D). The following key provisions of the SMP apply to the proposed BCF
impacts and mitigation requirements:
RMC 4-3-090.D.2.a.i—requires that shoreline use and development shall be carried out
in a manner that prevents or mitigates adverse impacts to ensure no net loss of
ecological functions and processes.
RMC 4-3-090.D.2.a.ii —requires that in assessing the potential for net loss of ecological
functions or processes, project-specific and cumulative impacts shall be considered and
mitigated on- or off-site.
RMC 4-3-090.D.2.c.iv—provides for flexibility in the administration of the ecological
protection provisions of the Shoreline Master Program, such that alternative mitigation
approaches may be applied for as provided in RMC 4-3-050.N.2, Modifications [sic]1.
1 Alternative mitigation approaches are found in RMC 4-3-090.L.1.g.iv
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6.2 Proposed Compensatory Mitigation
This section details the approach and conclusion to selecting the proposed compensatory
mitigation. Compensatory mitigation to offset the loss of ecological functions from the projects
consists of the following objectives:
Optimize gain of ecological function for the most sensitive resource (i.e., aquatic habitat
for Chinook salmon).
Use best available science and a watershed approach to site selection.
Provide a mitigation strategy that simultaneously satisfies local, state, and federal
requirements.
Select a site that is appropriately sized for the mitigation need.
Renton’s critical area regulations generally prioritize on-site mitigation (RMC 4-3-050.L.1.d) for
critical area impacts when it is feasible and likely to succeed long-term. However, if mitigation
on or adjacent to the development site is impractical or won’t result in meaningful ecological
benefit, off-site mitigation conducted under a watershed approach becomes the best option. In
accordance with RMC 4-3-050.G.6 and RMC 4-3-090.D.2.c.iv applicable to HCAs and the stated
mitigation objectives, SPU made an initial determination that the King County Mitigation
Reserves In Lieu Fee (ILF) Program provides the most appropriate compensatory mitigation for
the project impacts.
However, during preliminary coordination, City of Renton staff indicated that use of the ILF
program for compensatory mitigation would not be supported. The City cited unwritten policy
that compensatory mitigation must occur within City limits. Following this guidance, SPU
evaluated on-site and off-site options within the City of Renton.
Adhering to a watershed approach to identifying an optimal site, SPU reviewed its
Downstream Habitat Protection and Restoration Program to identify potential opportunities
near the project site and on SPU-owned property. The nearest site is 1.7 miles upriver of the
easternmost municipal limit of the City of Renton and the remaining sites are farther upriver
outside of Renton city limits. Properties owned by SPU as part of its Downstream Habitat
Protection and Restoration Program would provide only riparian and bank mitigation that does
not meet the stated mitigation objectives. Private property acquisition for mitigation is not
considered feasible or cost-effective for offsetting project impacts based on the small quantity of
mitigation required.
To further evaluate whether the mitigation objectives could be satisfied within the immediate
vicinity of the project site, SPU reviewed the Lower Cedar River Restoration Assessment Study
prepared for Renton Public Works (Herrera 2015). This study should represent the best
available science on these opportunities. Four sites on City of Renton property were identified,
in order of preference, that could potentially fit the project mitigation needs.
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Site 6 (RM 1.7-1.8)—Create shallow sandy alcove, add LWM, and plant riparian
vegetation on right bank upstream of existing “amphitheater” at Renton Community
Center Park that is heavily used for beach access.
Site 10 (RM 3.2)—Connect inlet and excavate outlet to create flow-through side-channel
conditions in left bank floodplain.
Site 4 (RM 1.1-1.6)—Remove invasive vegetation and plant native riparian vegetation on
left bank in areas where mature trees do not exist between Houser Way N and Logan
Ave N. Potential for large wood placement at toe of bank in selected locations.
Site 11 (RM 3.3-3.6)—Selectively plant native shading vegetation along both banks of
existing Cedar River Spawning Channel.
These sites are located on City of Renton property, which would require a City commitment to
dedicate these sites to conservation use in perpetuity. Feedback from the City Parks and Public
Works Departments indicated that use of these sites would not be supported because this action
would decrease the availability of these sites for future City mitigation projects.
For the reasons detailed above, the City and SPU have concluded that maximizing the available
on-site mitigation opportunity is the preferred approach to meet the stated mitigation
objectives.
SPU evaluated a range of potential on-site mitigation options. The project site is wholly within
the 100-year floodplain and is subject to seasonal flooding. For this reason, on-site mitigation
requires design objectives and flood protection measures to ensure long-term success and
performance of the mitigation design.
On-site mitigation would consist of a combination of aquatic and riparian elements. An LWM
complex is proposed along ordinary high water on the gravel bar approximately 130 feet
upstream of the proposed BCF to provide aquatic habitat complexity along the shallow channel
margin. Additionally, approximately 6,680 square feet of riparian habitat enhancement is
proposed to remove invasive species and install native trees and shrubs. Areas subject to
temporary disturbance during construction would also be restored with native vegetation to
preconstruction conditions once construction is complete. The proposed mitigation is discussed
in the following sections in further detail.
6.2.1 Conceptual Mitigation Design
SPU proposes to conduct riparian and channel margin enhancement on a total of 10,900 square
feet of the low flood terrace and gravel bar at the project site. Due to recent flooding in winter
2020, existing understory vegetation and LWM on the flood terrace was largely washed away.
Invasive species such as Japanese knotweed and Himalayan blackberry persist and are
recolonizing denuded soils.
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To provide an aquatic component to the mitigation design, an LWM complex is proposed along
the left bank to the Cedar River approximately 130 feet upstream of the proposed BCF. This
complex would be partially buried and anchored into the substrate with root wads oriented
toward the river to provide habitat complexity, cover, and woody substrate for algae and
macroinvertebrates. The final LWM complex would be designed to meet the following
objectives:
• Withstand 100-year flood event, plus safety factor.
• Surround root wads by a suitable range of flows at the channel margin during juvenile
salmon outmigration periods.
• Promote scour pool formation.
• Provide floodplain roughness element.
Proposed riparian improvements include restoration of the 3,733 square feet of temporary
clearing limits, re-establishment of riparian vegetation in 489 square feet of the existing boat
ramp removal, and enhancement of 6,680 square feet of degraded riparian buffer. Vegetation
management would include removal of invasive species and installation of native trees and
shrubs suitable to the site conditions. The planted area would be treated with an erosion control
fabric (e.g., jute or coir) and mulching as appropriate to promote plant establishment, erosion
control, and weed prevention.
Prior to planting, weeds would be controlled and the soil prepared as necessary (e.g., tilling,
organic mulch amendments). Planting would most likely occur in the fall (2019) following
completion of earthwork, to maximize successful plant establishment.
Weed control would be conducted using principles of an integrated pest management plan and
may be controlled by mowing, pulling, and/or targeted herbicide application as needed.
Adequate ground cover would be incorporated to inhibit weed colonization of exposed soils.
Installed woody plants would be surrounded with bark mulch at a 3-inch depth to establish
plants and inhibit weed growth.
The planting plan has been developed to establish a forested wetland and buffer community.
Plant selection guidance came from existing forested site vegetation, and from species
considered to be robust performers in restoration plantings. Table 3 includes a representative
plant schedule.
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Table 3. Proposed Plant Schedule
Common Name Scientific Name Size and Condition Plant spacing
(feet on center)
Black cottonwood Populus balsamifera ssp.
trichocarpa Live stake 3
Red alder Alnus rubra Bare root 3
Pacific wouldow Salix lasiandra Live stake 3
Snowberry Symphoricarpos albus Live stake/bare root 3
Nootka rose Rosa nutkana Bare root 3
Salmonberry Rubus spectabilis Bare root 3
Pacific ninebark Physocarpus capitatus Live stake 3
The conceptual mitigation design is shown in Figure 5. Final details and specifications for the
mitigation design would be developed during the upcoming 90% design phase in summer 2020.
July 2020 Page 40
Figure 5. Proposed Mitigation Concept
Cedar River Broodstock Collection Facility Replacement Critical Areas Report
July 2020 Page 41
6.2.2 Mitigation Ratios
The project would result in 3,733 square feet of temporary impact and 1,627 square feet of
permanent impact to riparian buffer, as well as 1,461 square feet of permanent impact to the
Cedar River. This section discusses compensatory mitigation ratios and the amount of
compensatory mitigation proposed for unavoidable impacts.
No specific provisions for mitigating alterations to HCAs exist in RMC 4-3-050J. RMC 4-3-
090.D.2.c.iv is the only provision that addresses HCA mitigation under the City critical areas
regulations. In this instance, the provisions of RMC 4-3-090.D apply to compensatory mitigation
under the SMP, which broadly requires no net loss of ecological functions.
The mitigation strategy proposed herein provides ecological functions that should outweigh the
ecological functions impacted from the BCF and are consistent with ratios typical of
compensatory mitigation under regional local regulations. Table 4 summarizes the proposed
areas of compensatory mitigation and ratios of mitigation to impact.
Table 4. Proposed Mitigation Ratios
Impact Type Impact Area
(square feet)
Mitigation Type
Proposed
Proposed mitigation
(square feet)
Ratio
Temporary Riparian
Clearing 3,733 Riparian Restoration 3,733 1:1
Permanent Riparian
Hardscaping 1,627
Riparian Re-
establishment 489
1:1 Riparian
Enhancement 1,138
Permanent Aquatic
Fill 1,461
Riparian
Enhancement 5,541 3.8:1
LWM Complex N/A N/A
Notes: RMC is silent on mitigation ratios for these resources. Proposed ratios are based on past precedents for mitigating
impacts to similar aquatic habitat and riparian areas.
N/A = Not applicable. LWM complex is not an area-based mitigation component.
6.2.3 Ecological Benefits
The proposed mitigation would benefit all salmonid species. As described in Section 5, the
principal impacts associated with the proposed BCF requiring mitigation include a loss of river
substrate supporting potential spawning and benthic production, and removal of riparian
vegetation. These ecological functions are not considered limiting in the project reach and effects
to fish production and stream ecology are not considered significant. The proposed on-site
mitigation would offset the loss of these functions over time through the following effect
pathways.
Cedar River Broodstock Collection Facility Replacement Critical Areas Report
July 2020 Page 42
The installation of LWM complex is anticipated to support salmonid production by providing a
quiescent holding area with complex cover at the channel margin. The LWM complex would be
designed to promote the formation of a scour pool suitable for use by adults of multiple salmonid
species during upstream migration and for pre-spawn holding. This reach has few pools and
areas of fish cover. Chinook salmon benefit from pool habitat because they rest and hold in pools
prior to spawning, often spawning in riffle habitat adjacent to pools. Suitable spawning habitat
occurs within close proximity to the proposed LWM complex. The LWM complex would also
support important rearing habitat for juvenile emigration which is limited in the project reach.
The importance of riparian buffers is well documented. As described above, riparian buffers
provide critical functions to healthy stream habitat such as erosion control, sediment and
pollutant removal, wood recruitment and organic litter production/trophic support,
microclimate influence, reduction of adjacent disturbances (e.g., noise, light), and habitat
maintenance and connectivity.
The mitigation site can be expected to perform a full suite of typical riparian functions. A
summary of specific ecological benefits related to the proposed riparian improvements follows:
The site experiences inundation from flood events and the riparian buffer would be
integrated with fluvial processes.
Increasing the roughness in the floodplain by establishing a forested community
throughout the aquatic habitat buffer would help moderate downstream peak flows.
The buffer would have a greater opportunity to slow flow velocities, allowing sediments
and organic debris to drop out of hydraulic suspension, and allowing filtration of
chemicals and nutrients from upslope sources.
Deposition of flood sediments and debris would provide nutrient cycling and trophic
support.
The floodplain represents an ecotone where both terrestrial and aquatic ecosystems mix
and there is a high degree of energy transfer, promoting species richness and greater
productivity.
The buffer would maintain cool water temperatures through shade and the creation of a
cool and humid microclimate in the riparian zone.
The riparian restoration and enhancement is specifically anticipated to support stream
productivity through generation of organic litter that is a foundational element of the
aquatic food web, and through the production of terrestrial insects.
Overall, the proposed on-site mitigation is expected to provide greater ecological benefit to the
Cedar River relative to the minor loss of function due to the project impacts. Because no net loss
of ecological functions to HCAs and the shoreline environment would occur, the project
satisfies the provisions of the RMC 4-3-090D.
Cedar River Broodstock Collection Facility Replacement Critical Areas Report
July 2020 Page 43
7.0 MITIGATION GOALS, OBJECTIVES, AND PERFORMANCE CRITERIA
SPU is committed to maintaining a successful, high-functioning mitigation site. This would be
accomplished through regular maintenance, monitoring of performance relative to pre-
established criteria, and adaptive maintenance, as necessary, to address any deficiencies in site
performance. Mitigation goals, objectives, and performance criteria are described below. The
section begins with a description of overall goals, and then each objective is stated, with
subsections defining the performance criteria and contingency measures for each objective.
Table 5 summarizes the performance criteria for all objectives.
Table 5. Performance Criteria
Performance Criteria
Monitoring Year
Year 0 Year 1 Year 2 Year 3 Year 5
Objective 1: Woody Riparian Buffer Community
1a: Plant Survival (percent) 100 100 70 NC NC
1b: Buffer Native Species Cover (percent) NC Baseline
measured 30 50 65
Objective 2: Trophic Support
2a: Plant Survival (percent) 100 100 70 NC NC
2b: Vegetative Strata NC NC NC Tree and shrub
strata present
Tree and shrub
strata present
Objective 3: Minimal Invasive Species
3: Invasive Species Percent
Cover NC Baseline
measured ≤20 ≤15 ≤10
Objective 4: Large Woody Material Complex
4a. Hydraulic engagement Summer low
flow
Summer low
flow
Summer low
flow
Summer low
flow
Summer low
flow
NC No Criterion
7.1 Goals
The overarching goal of this mitigation plan is to restore a woody riparian community that is
functionally connected to the Cedar River and similar to historic conditions. The area would be
dominated by forested riparian habitat with a shrub stratum.
7.2 Objectives
Four objectives have been identified to guide the mitigation design and subsequent
performance monitoring:
Cedar River Broodstock Collection Facility Replacement Critical Areas Report
July 2020 Page 44
Objective 1 – The mitigation area will be dominated with a healthy, native woody
riparian buffer plant community.
Objective 2 – The mitigation area will provide a diverse canopy for trophic support
consisting of both tree and shrub vegetative strata.
Objective 3 – The mitigation area will have a limited amount of invasive species.
Objective 4 – The mitigation area will have an LWM complex engaged with the wetted
portion of the river at an appropriate range of flows.
In the following sections, the performance criteria and contingency measures are described for
each objective.
7.2.1 Objective 1 – Woody Riparian Buffer
Performance Criteria 1a – Survival
Performance Evaluation
Planted vegetation and natural recruits within the mitigation area would be monitored for
survival for 3 years (Year 0 [as built], Year 1, and Year 2). Survival would not be monitored after
Year 2 because it is expected that plant growth and the amount of natural recruitment would
make identifying planted vegetation difficult. Additionally, some plants are expected to be
shaded out and die as a result of other tree and shrub growth. After Year 2, other performance
criteria would be more effective for evaluating the extent of native plants at the site. Monitoring
would occur in the late summer or early fall during each year monitoring is required. Table 5
shows the performance criteria for vegetation for each year of monitoring.
Contingency Measure
High mortality could result from improper installation, diseased or infested plants, herbivory,
unexpected events, inadequate watering, extreme weather, and flood events. If unusually high
mortality occurs, for whatever reason, and performance criteria are not on track to be met,
appropriate contingency measures would be taken. Contingency measures may include
supplemental plantings, irrigation, and controlling herbivory through use of species-
appropriate exclusion methods. Should damage occur due to recurrent flooding, specific
contingencies would be developed in coordination with the City of Renton.
Performance Criteria 1b – Percent Cover
Performance Evaluation
Planted vegetation and natural recruits within the upland buffer area would be monitored for
percent cover for 4 years over a 5-year period (Year 1, Year 2, Year 3, and Year 5). Monitoring
Cedar River Broodstock Collection Facility Replacement Critical Areas Report
July 2020 Page 45
would occur during the growing season after deciduous plants have flowered or leafed-out for
easier identification. Table 5 shows the success criteria for plant survival for each year of
monitoring.
Contingency Measure
High plant mortality could result from improper installation, diseased or infested plants,
inadequate watering, extreme weather, herbivory, and competition from invasive plant species.
If a percent cover success criterion is not met, the cause would be investigated and corrected.
Correction measures may include increased watering, soil amendments, control of invasive
species, herbivory protection, flood/erosion protection, or additional plantings of native species.
7.2.2 Objective 2 – Trophic Support
Performance Criteria 2a – Plant Survival
Performance Evaluation
Performance would be evaluated in the same manner as Performance Criteria 1a, and planted
vegetation and natural recruits within the mitigation area would be monitored for survival for 3
years (Year 0 [as built], Year 1, and Year 2). Table 5 shows the performance criteria for
vegetation for each year of monitoring.
Contingency Measure
Contingencies would follow those outlined in Performance Criteria 1a.
Performance Criteria 2b – Vegetative Strata
Performance Evaluation
Vegetative strata within the riparian buffer area would be monitored for the presence of both a
tree stratum and a shrub stratum for 2 years over a 5-year period (Year 4 and Year 5). Table 5
shows the success criteria for plant survival for each year of monitoring.
Contingency Measure
An imbalance of vegetative strata could result from high plant mortality, inter-species
competition, flood damage, and herbivory. If vegetative stratum success criterion is not met, the
cause would be investigated and corrected. Correction measures may include adjusting the
species in the planting mix, control of invasive species, flood/erosion protection, and herbivory
protection.
Cedar River Broodstock Collection Facility Replacement Critical Areas Report
July 2020 Page 46
7.2.3 Objective 3 – Invasive Species
Performance Criteria 3 – Percent Cover
Performance Evaluation
The percent cover of area dominated by invasive species would be monitored for 4 years over a
5-year period (Year 1, Year 2, Year 3, and Year 5). Monitoring would occur during the growing
season after deciduous plants have flowered or leafed-out for easier identification. Table 5
shows the success criteria for invasive species cover for each year of monitoring.
Contingency Measure
Dominance by invasive species could result from the disturbance of the soil, a high mortality
rate of the native planted vegetation, or colonization by windborne or waterborne seeds. If more
than 10% of the vegetated area is covered by invasive species, the cause of infestation would be
investigated, and corrective actions would be evaluated prior to implementing contingencies.
Contingency measures could include increasing the frequency of weed control until native
vegetation can grow and dominate the area or adaptively managing the weed control methods
to target specific causes of infestation.
7.2.4 Objective 4 – LWM Complex
Performance Criteria 4 – Hydraulic Engagement
Performance Evaluation
The performance evaluation for the LWM complex would document and verify that the
structure is established according to the criteria specified during the design The LWM complex
would be visually monitored to verify that it is hydraulically engaged within the wetted portion
of the stream for each year of the 5-year period. Monitoring would occur during the late
summer or early fall low-flow period. The structure would be inspected to ensure consistency
with the as-built condition, in which hydraulic engagement at higher flow conditions would be
assumed acceptable. Table 5 shows the success criteria for hydraulic engagement for each year
of monitoring.
Contingency Measure
Flooding, debris accumulation, and sediment deposition can compromise the stability and
performance of LWM structures in fluvial systems. If damage occurs, the cause would be
investigated, and corrective actions would be evaluated prior to implementing contingencies.
Specific contingencies would be developed in coordination with the City of Renton.
Cedar River Broodstock Collection Facility Replacement Critical Areas Report
July 2020 Page 47
8.0 MAINTENANCE
Maintenance activities in the mitigation area would change throughout the duration of the
monitoring and maintenance period. These activities would be concentrated within the period
immediately after installation and continue through the first and second years post-installation
as the vegetation becomes established. Additional maintenance after initial plant establishment
would be conducted on an as-needed basis. Maintenance activities would be conducted by SPU
or a contractor.
9.0 FINANCIAL ASSURANCES
SPU assumes financial responsibility for the aquatic habitat buffer mitigation in perpetuity. As
required by RMC 4-3-050.L.2, SPU would provide for financial assurances to implement
monitoring, maintenance, adaptive management, or site management actions through the use of
performance bonds, escrow accounts, letters of credit, or some other approved surety device as
necessary.
10.0 LONG-TERM MANAGEMENT AND SITE PROTECTION
The mitigation is proposed on City of Renton Park’s property. Long-term protection of the
mitigation site would be negotiated separately, through the Memorandum of Agreement
between the City of Renton and SPU.
Cedar River Broodstock Collection Facility Replacement Critical Areas Report
July 2020 Page 48
11.0 REFERENCES
Anderson, P.S., S. Meyer, P. Olson, and E. Stockdale. 2016. Determining the ordinary high water
mark for Shoreline Management Act compliance in Washington State. October 2016 final
review. Washington State Department of Ecology, Shorelands & Environmental Assistance
Program, Lacey, Washington. Ecology Publication No. 16-06-029.
Baumgartner, S.D., and C.T. Robinson. 2016. Short-term colonization dynamics of
macroinvertebrates in restored channelized streams. Hydrobiologia 784(1):321-335.
City of Renton. 2017. City of Renton: FEMA DFIRM update [online resource]. Available at:
https://rentonwa.gov/city_hall/public_works/utility_systems/surface_water_utility_engineer
ing/fema_dfirm_update (accessed March 11, 2020).
City of Renton. 2020. City of Renton: Maps of your community [online database]. Available at:
http://rp.rentonwa.gov/HTML5Public/Index.HTML?viewer=CORMaps (accessed February
24, 2020).
City of Seattle. 2000. Landsburg Mitigation Agreement for the fish migration barrier at the
Landsburg Diversion Dam [online document]. Agreement between the City of Seattle, the
Governor of State of Washington (Gary Locke), WDFW, NMFS, and USFWS. Available at:
https://www.seattle.gov/Documents/Departments/SPU/EnvironmentConservation/Landsbu
rgMitigationAgreementAgreement.pdf (accessed March 11, 2020).
Corps (U.S. Army Corps of Engineers). 1987. Corps of Engineers wetlands delineation manual.
Corps Environmental Laboratory, Waterways Experiment Station, Vicksburg, Mississippi.
Technical Report Y-87-1.
Corps. 2010. Regional supplement to the Corps of Engineers wetland delineation manual:
western mountains, valleys, and coast region. U.S. Army Engineer Research and
Development Center, Vicksburg, Mississippi. ERDC/EL TR-08-13.
Gendaszek, A.S., C.S. Magirl, C.R. Czuba. 2012. Geomorphic response to flow regulation and
channel and floodplain alteration in the gravel-bedded Cedar River, Washington, USA.
Geomorphology 179: 258-268.
Herrera Environmental Consultants, Inc. (Herrera). 2015. Lower Cedar River Chinook Salmon
Habitat Restoration Assessment Study. Prepared for City of Renton Public Works
Department Surface Water Utility, by Herrera Environmental Consultants, Inc. Seattle,
Washington.
Hruby, T. 2014. Washington State wetland rating system for western Washington, 2014 update.
Washington State Department of Ecology, Olympia. Publication # 14-06-029.
Kerwin, J., 2001. Salmon and steelhead habitat limiting factors report for the Cedar –
Sammamish basin (water resource inventory area 8). Washington Conservation
Commission. Olympia, Washington.
Cedar River Broodstock Collection Facility Replacement Critical Areas Report
July 2020 Page 49
King County. 2020. King County iMap [online database]. Available at:
https://gismaps.kingcounty.gov/iMap/ (accessed February 24, 2020).
Lichvar, R.W., D.L. Banks, W.N. Kirchner, and N.C. Melvin. 2016. The National Wetland Plant
List: 2016 wetland ratings. Phytoneuron 2016-30:1–17
Mackay, R.J. 1992. Colonization by lotic macroinvertebrates: a review of processes and patterns.
Canadian Journal of Fisheries and Aquatic Sciences 49(3):617-628.
Merz, J.E., and L.K. Ochikubo Chan. 2005. Effects of gravel augmentation on macroinvertebrate
assemblages in a regulated California river. River Research and Applications 21:61-74.
NMFS (National Marine Fisheries Service). 2011. Anadromous salmonid passage facility design.
NMFS, Northwest Region, Portland, Oregon.
NRCS (National Resources Conservation Service). 2020a. Web soil survey [online database].
U.S. Department of Agriculture, NRCS, Soil Science Division, Washington D.C. Available at:
http://websoilsurvey.nrcs.usda.gov/app/HomePage.htm (accessed February 25, 2020).
NRCS. 2020b. The PLANTS database [online database]. U.S. Department of Agriculture, NRCS,
National Plant Data Team, Greensboro, North Carolina. Available at:
https://plants.sc.egov.usda.gov/java/ (accessed on February 24, 2020).
USFWS (U.S. Fish and Wildlife Service). 2020. National wetlands inventory wetlands mapper
[online database]. U.S. Department of the Interior, Fish and Wildlife Service, Washington,
D.C. Available at: https://www.fws.gov/wetlands/Data/Mapper.html (accessed February 21,
2020).
WDFW (Washington Department of Fish and Wildlife). 2012. Invasive Species Management
Protocols. Version 2: November 2012. Produced by WDFW, Olympia, Washington.
Available at: https://wdfw.wa.gov/sites/default/files/publications/01490/wdfw01490.pdf
WDFW. 2020a. SalmonScape interactive mapping [online database]. Washington Department of
Fish and Wildlife, Olympia, Washington. Available at:
http://apps.wdfw.wa.gov/salmonscape/map.html (accessed February 24, 2020).
WDFW. 2020b. PHS on the web interactive mapping [online database]. Washington Department
of Fish and Wildlife Habitat Program, Olympia, Washington. Available at:
http://apps.wdfw.wa.gov/phsontheweb/ (accessed February 24, 2020).
WDNR (Washington Department of Natural Resources). 2020. Forest practices application
mapping tool. Olympia, Washington. Available at: https://fpamt.dnr.wa.gov/default.aspx#
(February 24, 2020).
WSDOT (Washington Department of Transportation). 2016. WSDOT fish exclusion protocols &
standards [online document]. Available online at:
Cedar River Broodstock Collection Facility Replacement Critical Areas Report
July 2020 Page 50
https://www.wsdot.wa.gov/sites/default/files/2017/10/26/Env-FW-FishMovingProtocols.pdf
(accessed February 26, 2020).
Appendix A
GIS Database
Search Results
This page intentionally left blank
for double-sided printing
9,028
752
City of Renton - Critical Areas
This map is a user generated static output from an Internet mapping site and
is for reference only. Data layers that appear on this map may or may not be
accurate, current, or otherwise reliable.
None
2/26/2020
Legend
5120 256
THIS MAP IS NOT TO BE USED FOR NAVIGATION
Feet
Notes
512
WGS_1984_Web_Mercator_Auxiliary_Sphere
Information Technology - GIS
RentonMapSupport@Rentonwa.gov
City and County Labels
City and County Boundary
Parcels
Coalmines
High
Moderate
Unclassified
Erosion Hazard - High
Floodway
Special Flood Hazard Areas (100
year flood)
Streets
Parks
Waterbodies
2019.sid
Red: Band_1
Green: Band_2
Blue: Band_3
Extent2010
9,028
752
City of Renton - Critical Areas
This map is a user generated static output from an Internet mapping site and
is for reference only. Data layers that appear on this map may or may not be
accurate, current, or otherwise reliable.
None
2/26/2020
Legend
5120 256
THIS MAP IS NOT TO BE USED FOR NAVIGATION
Feet
Notes
512
WGS_1984_Web_Mercator_Auxiliary_Sphere
Information Technology - GIS
RentonMapSupport@Rentonwa.gov
City and County Labels
City and County Boundary
Parcels
Landslide
Very High
High
Moderate
Unclassified
Seismic Hazard Areas
Faults
Streets
Parks
Waterbodies
2019.sid
Red: Band_1
Green: Band_2
Blue: Band_3
Extent2010
9,028
752
City of Renton - Critical Areas
This map is a user generated static output from an Internet mapping site and
is for reference only. Data layers that appear on this map may or may not be
accurate, current, or otherwise reliable.
None
2/26/2020
Legend
5120 256
THIS MAP IS NOT TO BE USED FOR NAVIGATION
Feet
Notes
512
WGS_1984_Web_Mercator_Auxiliary_Sphere
Information Technology - GIS
RentonMapSupport@Rentonwa.gov
City and County Labels
City and County Boundary
Parcels
Slope City of Renton
>15% & <=25%
>25% & <=40% (Sensitive)
>40% & <=90% (Protected)
>90% (Protected)
Streams (Classified)
<all other values>
Type S Shoreline
Type F Fish
Type Np Non-Fish
Type Ns Non-Fish Seasonal
Unclassified
Not Visited
Wetlands
Streets
Parks
Waterbodies
2019.sid
Red: Band_1
Green: Band_2
Blue: Band_3
Extent2010
9,028
752
City of Renton - Critical Areas
This map is a user generated static output from an Internet mapping site and
is for reference only. Data layers that appear on this map may or may not be
accurate, current, or otherwise reliable.
None
2/26/2020
Legend
5120 256
THIS MAP IS NOT TO BE USED FOR NAVIGATION
Feet
Notes
512
WGS_1984_Web_Mercator_Auxiliary_Sphere
Information Technology - GIS
RentonMapSupport@Rentonwa.gov
City and County Labels
City and County Boundary
Parcels
Wellhead Protection Area Zones
Zone 1
Zone 1 Modified
Zone 2
Streets
Parks
Waterbodies
2019.sid
Red: Band_1
Green: Band_2
Blue: Band_3
Extent2010
RENTONRENTON
SEATTLESEATTLE
MERCERMERCER
ISLANDISLAND
KING COUNTYKING COUNTY
KING COUNT
Y
KING COUNT
Y
KENTKENT
KING COUNTYKING COUNTY
NEWCASTLENEWCASTLE
TUKWILATUKWILA RREENNTTOONNRENTONRENTON
KKIINNGG CCOOUUNNTTYY
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NEWCAST
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NEWCASTLENEWCASTLE
KING COUNTYKING COUNTYKENTKENTKENTKENT
TUKWILATUKWILATUKWILATUKWILASEATTLESEATTLE HoquiamAveNETalbotRdSS PugetDr
SE Jo n e s R d
LindAveSWMonroe Ave NEEdmondsAveNES 7th St Williams Ave SNewcastleWay
T
a
yl
o
r
P
l
N
WWells Ave N87thAveSWellsAveSNE 7 t h S tLoganAveS128th Ave SEBensonRdS
S E 183rdSt
SW 41st St 116th Ave SESE 168th St UnionAveNESW 7th St LakeWashingtonBlvdSEP u g etDrSESW 16th St Har
d
i
e
A
v
e
S
WSW 34th St
EastValley RdSW 27th St
E Valley Hwy84th Ave SSouthp o rt DrN
KlickitatDr
S 1 7 8th St 154thPl SE51st Ave SS 132nd St
N 3rd St64th Ave SRentonAveS
Tukwila Pk w ySewardParkAveS51st Ave S68thAveSDuva
llAveNEE M e rcerWayS 129 t h S tN 4th St
SE 128th St
MilitaryRdSI
n
t
erurbanAveS
124th Ave SERaini
er
AveNNE 3 rd S tR a i n i e r A v e S
OakesdaleAveS
WLakemontBlvdSE50t
h
PlS
SouthcenterPkwySW 43rd St
S E Carr R d
Be
a
c
o
n
A
v
e
S
NE 4th StLoganAveN
Forest Dr SE
S G r a d y W ayParkAveN156thAveSES 12 4t h StSRyanW ay
148th Ave SESE 192nd St
Southcenter Blvd
S 180th St 164th Ave SEAirport Way
S W G r ad y
W
ay
SE204thW ayS Othello St
C
o
a
l
Cr
eek
Pk
wy
S
E
WMercerWay
Monster RdSW
SE 208th St
SEMayValley Rd
14 0 th A veSE140thWaySE
SE Petrovitsky Rd
Newcastle GolfClubRd
NE P a rk D rS 133rd St
UV169
UV169
UV900
UV515
UV900
UV900
UV900
UV900
UV515
UV515
UV181
UV181
UV518
UV900
UV518
UV900
UV167
UV167
§¨¦405
§¨¦405
§¨¦405
§¨¦405
§¨¦5
§¨¦5
§¨¦405
Preliminary - Flood Zone (2017)
Zone A
Zone AE
Zone AE (Floodway)
Zone AH
Zone AO
Zone X (Shaded)
Zone X (Levee)
Renton City Limits
The Federal Emergency Management Agency (FEMA) has converted all flood
insurance rate maps into digital flood insurance rate maps. FEMA published
preliminary Digital Flood Insurance Rate Maps (DFIRM) for public review in
September 2017. The proposed floodplain maps reflect changes to the current
effective Federal Emergency Management Agency DFIRM. Within Renton, the
floodplain map changes are in the Cedar River valley. The current effective flood
hazard information has been retained on the Green River until new flood hazard
analysis and mapping is completed. The current flood insurance rate map for
the Green River is dated May 16, 1995.
City of Renton Preliminary Floodplain Map
Public Works - GIS Surface Water Utility
Print Date: 03/16/2018
Data Sources: City of Renton, King County, FEMA
This document is a graphic representation, not guaranteed to survey accuracy, and is based on the best
information available as of the date shown. This map is intended for City display purposes only.
Scan QR code to view parcel level map application on your mobile device
1 0 10.5 Miles
SPU Broodstock CF
U.S. Fish and Wildlife Service, National Standards and Support Team,
wetlands_team@fws.gov
Wetlands
Estuarine and Marine Deepwater
Estuarine and Marine Wetland
Freshwater Emergent Wetland
Freshwater Forested/Shrub Wetland
Freshwater Pond
Lake
Other
Riverine
February 25, 2020
0 0.1 0.20.05 mi
0 0.15 0.30.075 km
1:7,218
This page was produced by the NWI mapper
National Wetlands Inventory (NWI)
This map is for general reference only. The US Fish and Wildlife
Service is not responsible for the accuracy or currentness of the
base data shown on this map. All wetlands related data should
be used in accordance with the layer metadata found on the
Wetlands Mapper web site.
9
Custom Soil Resource Report
Soil Map
525850052585905258680525877052588605258950525904052591305259220525850052585905258680525877052588605258950525904052591305259220560130 560220 560310 560400 560490 560580 560670
560130 560220 560310 560400 560490 560580 560670
47° 29' 1'' N 122° 12' 7'' W47° 29' 1'' N122° 11' 40'' W47° 28' 37'' N
122° 12' 7'' W47° 28' 37'' N
122° 11' 40'' WN
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 10N WGS84
0 150 300 600 900
Feet
0 50 100 200 300
Meters
Map Scale: 1:3,680 if printed on A portrait (8.5" x 11") sheet.
Soil Map may not be valid at this scale.
MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Map Unit Polygons
Soil Map Unit Lines
Soil Map Unit Points
Special Point Features
Blowout
Borrow Pit
Clay Spot
Closed Depression
Gravel Pit
Gravelly Spot
Landfill
Lava Flow
Marsh or swamp
Mine or Quarry
Miscellaneous Water
Perennial Water
Rock Outcrop
Saline Spot
Sandy Spot
Severely Eroded Spot
Sinkhole
Slide or Slip
Sodic Spot
Spoil Area
Stony Spot
Very Stony Spot
Wet Spot
Other
Special Line Features
Water Features
Streams and Canals
Transportation
Rails
Interstate Highways
US Routes
Major Roads
Local Roads
Background
Aerial Photography
The soil surveys that comprise your AOI were mapped at
1:24,000.
Warning: Soil Map may not be valid at this scale.
Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil
line placement. The maps do not show the small areas of
contrasting soils that could have been shown at a more detailed
scale.
Please rely on the bar scale on each map sheet for map
measurements.
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:
Coordinate System: Web Mercator (EPSG:3857)
Maps from the Web Soil Survey are based on the Web Mercator
projection, which preserves direction and shape but distorts
distance and area. A projection that preserves area, such as the
Albers equal-area conic projection, should be used if more
accurate calculations of distance or area are required.
This product is generated from the USDA-NRCS certified data as
of the version date(s) listed below.
Soil Survey Area: King County Area, Washington
Survey Area Data: Version 15, Sep 16, 2019
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Jul 1, 2019—Jul 25,
2019
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor
shifting of map unit boundaries may be evident.
Custom Soil Resource Report
10
Map Unit Legend
Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI
AkF Alderwood and Kitsap soils,
very steep
3.8 6.3%
AmC Arents, Alderwood material, 6 to
15 percent slopes
7.5 12.5%
Pc Pilchuck loamy fine sand 10.9 18.1%
Rh Riverwash 7.8 12.9%
Ur Urban land 26.7 44.4%
W Water 3.5 5.8%
Totals for Area of Interest 60.3 100.0%
Map Unit Descriptions
The map units delineated on the detailed soil maps in a soil survey represent the
soils or miscellaneous areas in the survey area. The map unit descriptions, along
with the maps, can be used to determine the composition and properties of a unit.
A map unit delineation on a soil map represents an area dominated by one or more
major kinds of soil or miscellaneous areas. A map unit is identified and named
according to the taxonomic classification of the dominant soils. Within a taxonomic
class there are precisely defined limits for the properties of the soils. On the
landscape, however, the soils are natural phenomena, and they have the
characteristic variability of all natural phenomena. Thus, the range of some
observed properties may extend beyond the limits defined for a taxonomic class.
Areas of soils of a single taxonomic class rarely, if ever, can be mapped without
including areas of other taxonomic classes. Consequently, every map unit is made
up of the soils or miscellaneous areas for which it is named and some minor
components that belong to taxonomic classes other than those of the major soils.
Most minor soils have properties similar to those of the dominant soil or soils in the
map unit, and thus they do not affect use and management. These are called
noncontrasting, or similar, components. They may or may not be mentioned in a
particular map unit description. Other minor components, however, have properties
and behavioral characteristics divergent enough to affect use or to require different
management. These are called contrasting, or dissimilar, components. They
generally are in small areas and could not be mapped separately because of the
scale used. Some small areas of strongly contrasting soils or miscellaneous areas
are identified by a special symbol on the maps. If included in the database for a
given area, the contrasting minor components are identified in the map unit
descriptions along with some characteristics of each. A few areas of minor
components may not have been observed, and consequently they are not
mentioned in the descriptions, especially where the pattern was so complex that it
was impractical to make enough observations to identify all the soils and
miscellaneous areas on the landscape.
Custom Soil Resource Report
11
Bull Trout Streams
Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO, USGS,
FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri
Japan, METI, Esri China (Hong Kong), (c) OpenStreetMap contributors, and
the GIS User Community
WDFW
Bull Trout
Documented Spawning
Documented Rearing
Documented Presence
Documented-Artificial, Spawning
Documented-Artificial, Rearing
Documented-Artificial, Presence
Transported Spawning
Transported Rearing
Transported Presence
Presumed Presence
Potential: Blocked
Gradient Accessible
Documented Historic Presence
February 26, 2020
0 0.15 0.30.075 mi
0 0.2 0.40.1 km
1:9,028
Fall Chinook Streams
Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO, USGS,
FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri
Japan, METI, Esri China (Hong Kong), (c) OpenStreetMap contributors, and
the GIS User Community
WDFW
Fall Chinook Streams
Documented Spawning
Documented Rearing
Documented Presence
Documented-Artificial, Spawning
Documented-Artificial, Rearing
Documented-Artificial, Presence
Transported Spawning
Transported Rearing
Transported Presence
Presumed Presence
Potential: Blocked
Gradient Accessible
Documented Historic Presence
February 26, 2020
0 0.15 0.30.075 mi
0 0.2 0.40.1 km
1:9,028
Coho Streams
Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO, USGS,
FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri
Japan, METI, Esri China (Hong Kong), (c) OpenStreetMap contributors, and
the GIS User Community
WDFW
Coho Streams
Documented Spawning
Documented Rearing
Documented Presence
Documented-Artificial, Spawning
Documented-Artificial, Rearing
Documented-Artificial, Presence
Transported Spawning
Transported Rearing
Transported Presence
Presumed Presence
Potential: Blocked
Gradient Accessible
Documented Historic Presence
February 26, 2020
0 0.15 0.30.075 mi
0 0.2 0.40.1 km
1:9,028
Kokanee Streams
Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO, USGS,
FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri
Japan, METI, Esri China (Hong Kong), (c) OpenStreetMap contributors, and
the GIS User Community
WDFW
Kokanee
Documented Spawning
Documented Rearing
Documented Presence
Documented-Artificial, Spawning
Documented-Artificial, Rearing
Documented-Artificial, Presence
Transported Spawning
Transported Rearing
Transported Presence
Presumed Presence
Potential: Blocked
Gradient Accessible
Documented Historic Presence
February 26, 2020
0 0.15 0.30.075 mi
0 0.2 0.40.1 km
1:9,028
Sockeye Streams
Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO, USGS,
FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri
Japan, METI, Esri China (Hong Kong), (c) OpenStreetMap contributors, and
the GIS User Community
WDFW
Sockeye Streams
Documented Spawning
Documented Rearing
Documented Presence
Documented-Artificial, Spawning
Documented-Artificial, Rearing
Documented-Artificial, Presence
Transported Spawning
Transported Rearing
Transported Presence
Presumed Presence
Potential: Blocked
Gradient Accessible
Documented Historic Presence
February 26, 2020
0 0.15 0.30.075 mi
0 0.2 0.40.1 km
1:9,028
Winter Steelhead Streams
Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO, USGS,
FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri
Japan, METI, Esri China (Hong Kong), (c) OpenStreetMap contributors, and
the GIS User Community
WDFW
Winter Steelhead Streams
Documented Spawning
Documented Rearing
Documented Presence
Documented-Artificial, Spawning
Documented-Artificial, Rearing
Documented-Artificial, Presence
Transported Spawning
Transported Rearing
Transported Presence
Presumed Presence
Potential: Blocked
Gradient Accessible
Documented Historic Presence
February 26, 2020
0 0.15 0.30.075 mi
0 0.2 0.40.1 km
1:9,028
SOURCE DATASET:WASHINGTON DEPARTMENT OF FISH AND WILDLIFEPRIORITY HABITATS AND SPECIES REPORTREPORT DATE:P200224155839PHSPlusPublic02/24/2020 3.59Query ID:Priority AreaCommon NameAccuracySource EntityOccurrence TypeResolutionNotesSource DateSite NamePHS Listing StatusScientific NameSource DatasetState StatusMgmt RecommendationsMore Information (URL)Sensitive DataFederal StatusGeometry TypeSource RecordN/APolygonsN/A1/4 mile (Quarter902688AS MAPPEDN/ACEDAR RIVER VALLEY OPENPHSREGIONBiodiversity Areas AndPHS LISTEDWA Dept. of Fish and Wildlifehttp://wdfw.wa.gov/publications/pub.php?NTerrestrial HabitatOccurrencehttp://wdfw.wa.gov/wlm/diversty/soc/soc.htmLinesN/ANA1144AS MAPPEDThreatenedCedar RiverSASIChinookPHS ListedWDFW Fish ProgramNOncorhynchus tshawytschaOccurrenceBreeding areahttp://wdfw.wa.gov/wlm/diversty/soc/soc.htmLinesN/ANA38799AS MAPPEDN/ACedar RiverSWIFDCohoPHS LISTEDNOncorhynchus kisutchBreeding AreaOccurrencehttp://wdfw.wa.gov/wlm/diversty/soc/soc.htmLinesN/ANA3130AS MAPPEDCandidateCedar RiverSASICohoPHS ListedWDFW Fish ProgramNOncorhynchus kisutchOccurrenceOccurrence/migrationhttp://wdfw.wa.gov/wlm/diversty/soc/soc.htmLinesN/ANA38802AS MAPPEDN/ACedar RiverSWIFDDolly Varden/ Bull TroutPHS LISTEDNSalvelinus malmaOccurrence/MigrationBreeding areahttp://wdfw.wa.gov/wlm/diversty/soc/soc.htmLinesN/ANA38795AS MAPPEDN/ACedar RiverSWIFDFall ChinookPHS LISTEDNOncorhynchus tshawytschaBreeding AreaOccurrence/migrationhttp://wdfw.wa.gov/wlm/diversty/soc/soc.htmLinesN/ANA38805AS MAPPEDN/ACedar RiverSWIFDKokaneePHS LISTEDNOncorhynchus nerkaOccurrence/Migration02/24/2020 3.591
Priority AreaCommon NameAccuracySource EntityOccurrence TypeResolutionNotesSource DateSite NamePHS Listing StatusScientific NameSource DatasetState StatusMgmt RecommendationsMore Information (URL)Sensitive DataFederal StatusGeometry TypeSource RecordOccurrence/migrationhttp://wdfw.wa.gov/wlm/diversty/soc/soc.htmLinesN/ANA38793AS MAPPEDN/ACedar RiverSWIFDResident Coastal CutthroatPHS LISTEDNOncorhynchus clarkiOccurrence/MigrationBreeding areahttp://wdfw.wa.gov/wlm/diversty/soc/soc.htmLinesN/ANA38808AS MAPPEDN/ACedar RiverSWIFDSockeyePHS LISTEDNOncorhynchus nerkaBreeding AreaOccurrencehttp://wdfw.wa.gov/wlm/diversty/soc/soc.htmLinesN/ANA5400AS MAPPEDNot WarrantedCedar RiverSASISockeyePHS ListedWDFW Fish ProgramNOncorhynchus nerkaOccurrenceOccurrencehttp://wdfw.wa.gov/wlm/diversty/soc/soc.htmLinesN/ANA6154AS MAPPEDThreatenedCedar RiverSASISteelheadPHS ListedWDFW Fish ProgramNOncorhynchus mykissOccurrenceBreeding areahttp://wdfw.wa.gov/wlm/diversty/soc/soc.htmLinesN/ANA38812AS MAPPEDN/ACedar RiverSWIFDWinter SteelheadPHS LISTEDNOncorhynchus mykissBreeding AreaDISCLAIMER. This report includes information that the Washington Department of Fish and Wildlife (WDFW) maintains in a central computer database. It is not an attempt to provide you with an official agency responseas to the impacts of your project on fish and wildlife. This information only documents the location of fish and wildlife resources to the best of our knowledge. It is not a complete inventory and it is important to note that fishand wildlife resources may occur in areas not currently known to WDFW biologists, or in areas for which comprehensive surveys have not been conducted. Site specific surveys are frequently necesssary to rule out thepresence of priority resources. Locations of fish and wildlife resources are subject to vraition caused by disturbance, changes in season and weather, and other factors. WDFW does not recommend using reports more thansix months old.02/24/2020 3.592
WDFW Test Map
Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus
DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community
PHS Report Clip Area
PT
LN
POLY
AS MAPPED
SECTION
QTR-TWP
TOWNSHIP
February 24, 2020
0 0.3 0.60.15 mi
0 0.55 1.10.275 km
1:19,842
Extreme care was used during the compilation of this map to ensure
its accuracy. However, due to changes in data and the need to
rely on outside information, the Department of Natural Resources
cannot accept responsibility for errors or omissions, and therefore,
there are no warranties that accompany this material.
0 0.25
Miles
Date: 2/24/2020 Time: 4:07:20 PM
Map Symbols Additional Information Legal Description
Forest Practices Activity Map - Application #______________
¯
S18 T23.0N R05.0E, S17 T23.0N R05.0ES21 T23.0N R05.0E, S19 T23.0N R05.0ES20 T23.0N R05.0E, S16 T23.0N R05.0ES09 T23.0N R05.0E, S08 T23.0N R05.0ES07 T23.0N R05.0E*Waste Area
~~~Harvest Boundary
Stream
Ç Rock Pit
U Landing
Y Clumped
WRTS/GRTS
× Existing Structure
Road Construction
RMZ / WMZ Buffers
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Appendix B
BCF 60% Design Drawings
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for double-sided printing
60% (NOT FOR CONSTRUCTION)
G-001
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
G-002
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
G-003
ASSOCIATES
JACOBS
McMILLEN
℄
⅊
60% (NOT FOR CONSTRUCTION)
G-101
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
G-102
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
G-103
ASSOCIATES
JACOBS
McMILLEN
W
W
W
W SFSF
SF
S
F
SFSF
SF
SF
SF
SF
SF
SF
SF
SFSFSF60% (NOT FOR CONSTRUCTION)
C-101
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
C-201
ASSOCIATES
JACOBS
McMILLEN
≤
≤
≤
≤
≤
60% (NOT FOR CONSTRUCTION)
C-202
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
CD101
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
CD203
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
CS101
ASSOCIATES
JACOBS
McMILLEN
·
·
60% (NOT FOR CONSTRUCTION)
CS102
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
CS103
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
CS104
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
CS105
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
CS106
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
CS203
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
CS204
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
CS206
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
S-101
ASSOCIATES
JACOBS
McMILLEN
8
19
7 6
2 31
18
60% (NOT FOR CONSTRUCTION)
S-102
ASSOCIATES
JACOBS
McMILLEN
4
5
60% (NOT FOR CONSTRUCTION)
S-103
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
S-104
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
S-105
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
S-106
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
S-201
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
S-202
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
S-203
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
S-204
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
S-206
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
S-207
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
S-208
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
S-212
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
S-213
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
S-215
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
S-216
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
S-217
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
S-220
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
S-221
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
M-101
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
M-102
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
M-201
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
M-202
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
M-207
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
M-208
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
E-001
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
E-002
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
E-003
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
E-101
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
E-201
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
E-202
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
E-301
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
E-302
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
E-303
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
E-304
ASSOCIATES
JACOBS
McMILLEN
60% (NOT FOR CONSTRUCTION)
E-305
ASSOCIATES
JACOBS
McMILLEN
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Appendix C
Wetland Delineation
Methods
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for double-sided printing
146 N Canal St, Suite 111 • Seattle, WA 98103 • www.confenv.com
CONFLUENCE ENVIRONMENTAL COMPANY WETLAND DELINEATION METHODS
Prepared by:
Confluence Environmental Company
2020
WETLAND DELINEATION METHODS
2020 Page i
TABLE OF CONTENTS
1.0 WETLANDS .......................................................................................................................................................... 1
1.1 Methods Used to Determine Wetlands ..................................................................................................... 1
1.2 Wetland Criteria ........................................................................................................................................ 2
1.2.1 Hydrophytic Vegetation ............................................................................................................. 2
1.2.2 Hydric Soils ............................................................................................................................... 3
1.2.3 Hydrology .................................................................................................................................. 4
2.0 REFERENCES ...................................................................................................................................................... 4
WETLAND DELINEATION METHODS
2020 Page 1
This report describes the methods used to determine the presence or absence of critical areas in
a project area.
1.0 WETLANDS
1.1 Methods Used to Determine Wetlands
Confluence delineates the boundaries of wetlands using the “Routine Determinations for Areas
Less Than 5 Acres in Size” method described by the U.S. Army Corps of Engineers (Corps) in
the Corps of Engineers Wetlands Delineation Manual (Delineation Manual; Corps 1987) and the
Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Western Mountains,
Valleys, and Coast Region (Corps 2010) (Regional Supplement). The Regional Supplement was
part of a nationwide effort to address regional wetland characteristics and improve the accuracy
and efficiency of wetland-delineation procedures. The Regional Supplement uses the best
available science to addresses regional differences in climate, geology, soils, hydrology, and
plant and animal communities that cannot be addressed in a single national document, such as
the Delineation Manual. The Regional Supplement was designed for use with the 1987
Delineation Manual and all subsequent versions. Where differences in the 2 documents occur,
the Regional Supplement takes precedence over the 1987 Delineation Manual (Corps 2010). The
Regional Supplement was developed to clarify the indicators of hydrophytic vegetation, hydric
soils, and wetland hydrology found in the region (these indicators are discussed in detail in the
section below). It is important to note that areas that may have been determined as a wetland
under the 1987 Delineation Manual may not be determined as wetland under the Regional
Supplement, and vice versa.
Confluence uses the PLANTS Database (NRCS 2020) for scientific names and the 2016 National
Wetland Plant List (Lichvar et al. 2016) to determine the wetland indicator status of plants.
Wetlands are classified using the Cowardin Classification System (FGDC 2013). Confluence
determines the wetland rating using Washington State Department of Ecology’s Wetland
Rating System for Western Washington (Hruby 2014). The National Wetland Inventory is also
researched to determine if wetlands have previously been identified on the property (USFWS
2020).
The locations of test plots, soil cores, and wetland edges on a project property are recorded
using a differential Global Positioning System with sub-meter accuracy. Delineated and
surveyed wetland boundaries are subject to verification and approval by jurisdictional agencies.
WETLAND DELINEATION METHODS
2020 Page 2
1.2 Wetland Criteria
There is specific technical language that applies to the study of wetlands. This section briefly
explains the language Confluence uses in its wetland delineation reports.
The identification of wetlands is based on 3 criteria: hydrophytic vegetation, hydric soils, and
hydrology. Each criterion has a number of indicators by which it can be determined to satisfy
the standard. The Corps, which is the federal authority on the regulation of wetlands, has
developed the guidance and the Data Sheet that are the standards used in all wetland
determinations. The information presented below is based on their Wetland Delineation
Manual (Corps 1987) and Regional Supplement (Corps 2010).
In order to characterize a wetland, data are collected from representative test plots. The
delineator chooses areas both within and outside of a potential wetland that are representative
of particular vegetative, topographic, and hydrologic features in the vicinity. Those areas then
become test plots where particular data (see sections below) about vegetation, soils, and
hydrology are collected to determine whether wetland characteristics are present. Plots that
meet all 3 wetland criteria are wetland plots; plots that do not meet the 3 wetland criteria are
upland plots. The test plots (along with topographic and vegetative shifts) then inform the
wetland boundaries, with wetland plots being within the wetlands and upland plots being
outside of the wetlands.
1.2.1 Hydrophytic Vegetation
Vegetation is often the first visual cue that an area is a wetland. Similarly, vegetation often also
signals the shift from wetland to nonwetland. The question regarding plants to be answered
when performing a wetland delineation is: “Is the vegetation hydrophytic?” That is, is the
vegetation of the variety that is adapted to live in wetter-than-average conditions? To determine
the answer, there are a few resources and steps to follow. First, the indicator status for each
plant present in the test plot is determined from the National Wetland Plant List (Lichvar et al.
2016). The indicator status is a continuum from almost exclusively occurring in wetlands
(obligate wetland plants, or OBL) to almost exclusively never found in wetlands (obligate
upland plants, or UPL). The middle ground between those 2 extremes is known as a facultative
plant (or FAC), which is found equally in wetland and upland environments. The FAC category
has 2 further gradations: facultative upland plants (FACU), which are plants that are usually
found in uplands, and facultative wetland plants (FACW), which are plants that are usually
found in wetlands.
After the status of each plant species in the test plot has been determined, the hydrophytic
vegetation indicator can be applied. The application of the indicators is performed sequentially,
and once one is “passed,” the box for hydrophytic vegetation is “checked,” and the process
continues to the next criterion. The first hydrophytic vegetation indicator is the “Rapid Test,”
which means with a quick visual survey, all the plants in the test plot are either OBL or FACW.
WETLAND DELINEATION METHODS
2020 Page 3
The second test is the “Dominance Test.” For the Dominance Test, the total number of dominant
species in the test plot is divided by the number of species that are OBL, FACW, or FAC. The
resulting percentage must be greater than 50 to pass this test. The third test is the “Prevalence
Index.” The Prevalence Index is a weighted average of the absolute cover of all the plant species
present in the plot, regardless of dominance. There are also 2 other, less common, indicators:
morphological adaptations (e.g., buttressed trunks), or nonvascular plant species (e.g.,
sphagnum moss).
1.2.2 Hydric Soils
The soils tell the story about the presence of water over time. The National Technical Committee
defines a hydric soil as: “...a soil that formed under conditions of saturation, flooding, or
ponding long enough during the growing season to develop anaerobic conditions in the upper
part.” (USDA 1994) The question to be answered here is: “Has water been present long enough
and recently enough to form hydric soils?” In order to examine the soil characteristics, a test pit
must be dug, usually to about 18 inches. A sliver of soil from the test pit is extracted with a
shovel (i.e., the soil profile) to examine the layers. The thickness, color, texture, redoximorphic
features, and any other interesting information about each layer is observed and recorded.
Those features are described more fully in the bullets below.
Thickness. Layers are measured to the nearest inch. Usually, each soil profile has at least
2 layers.
Color. Color is determined by comparison to a color chart. The industry standard is the
Munsell Soil-Color Chart, which assigns each color a designation for hue, value, and
chroma (e.g., 10YR 3/2, where 10YR=hue, 3=value, and 2=chroma).
Texture. The precision of texture description for the purpose of wetland delineation is at
a general scale. The Washington State University texture chart (Cogger 2010) is often
used, but the delineator just needs to determine if the soil is sandy or loamy/clayey.
Redox Features. The most common redoximorphic features are concentrations or
depletions of iron in the soil matrix. Concentrations occur as red or yellow deposits, and
depletions occur as grayish deposits.
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When the soil profile is fully described, it can be determined if any
of the layers meet a hydric soil indicator. Hydric soil indicators
help to identify hydric soils. The presence of any indicator signifies
a hydric soil, although a soil may be hydric and not meet any
indicators. There are 19 hydric soil indicators in our region (Corps
2010). Additional hydric soil terminology definitions are in the
sidebar.
1.2.3 Hydrology
Wetland hydrology is the broadest criterion and has to do with
signs of saturation and inundation in the test plot. While
hydrophytic vegetation and hydric soils are the result of
hydrology, they remain even during the dry season, whereas
hydrology can be less apparent or absent during the dry season.
The hydrology indicators are broad enough to encompass
characteristics that may be present even during the dry season.
Hydrology indicators are in 4 groups:
Group A is based on direct observation of surface or
ground water;
Group B consists of evidence that the site is subject to
inundation;
Group C consists of other evidence that soil is or was
saturated; and
Group D consists of landscape, vegetation, and soil
characteristics indicating contemporary wet conditions.
The indicators are further divided into 2 categories: primary and secondary. A test plot must
have either 1 primary or 2 secondary indicators to pass the hydrology criterion. Primary and
secondary indicators observed during this delineation are recorded on the wetland delineation
data forms in Appendix C.
2.0 REFERENCES
Cogger, C.G. 2010. Estimating soil texture flowchart. Washington State University Puyallup
Research Center, Puyallup, Washington.
Corps (U.S. Army Corps of Engineers). 1987. Corps of Engineers Wetlands Delineation Manual.
Corps Environmental Laboratory, Waterways Experiment Station, Technical Report Y-87-1,
Vicksburg, Mississippi.
More Hydric Soils Definitions
(adapted from Corps 2010)
Matrix: the dominant soil volume in a
given soil layer
Depleted Matrix: the volume of a soil
horizon in which soil processes have
removed or transformed iron, creating
colors of low chroma and high value,
specifically:
Value ≥5, chroma = 1, with or
without redoximorphic features
Value ≥6, chroma = 1 or 2, with
or without redoximorphic
features
Value of 4 or 5, chroma =2, ≥2%
distinct or prominent
redoximorphic features
Value of 4, chroma =1, ≥2%
distinct or prominent
redoximorphic features
Distinct: readily seen, but
contrasting* moderately with
comparison color
Prominent: readily seen and
contrasting* greatly with comparison
color
*See Corps 2010, Table A1, page 130 for full
key on contrast determinations.
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Corps. 2010. Regional Supplement to the Corps of Engineers Wetland Delineation Manual:
Western Mountains, Valleys, and Coast Region. U.S. Army Engineer Research and
Development Center, ERDC/EL TR-08-13, Vicksburg, Mississippi.
FGDC (Federal Geographic Data Committee). 2013. Classification of wetlands and deepwater
habitats of the United States. Second Edition. Wetlands Subcommittee, Federal Data
Committee and U.S. Fish and Wildlife Service, Publication FGDC-STD-004-2013,
Washington, D.C.
Hruby, T. 2014. Washington State wetland rating system for western Washington, 2014 update.
Washington State Department of Ecology, Publication #14-06-029, Olympia, Washington.
Lichvar, R.W., D.L. Banks, W.N. Kirchner, and N.C. Melvin. 2016. The national wetland plant
list: 2016 wetland ratings. Phytoneuron 2016-30:1–17.
NRCS (National Resources Conservation Service). 2020. Web soil survey [online database]. U.S.
Department of Agriculture, NRCS, Soil Science Division, Washington D.C. Available at:
http://websoilsurvey.nrcs.usda.gov/app/HomePage.htm (accessed on February 24, 2020).
NRCS (National Resources Conservation Service). 2020. The PLANTS database [online
database]. U.S. Department of Agriculture, NRCS, National Plant Data Team, Greensboro,
North Carolina. Available at: https://plants.sc.egov.usda.gov/java/ (accessed on February 24,
2020).
USDA (U.S. Department of Agriculture) Soil Conservation Service. 1994. Changes in hydric soils
of the United States. Federal Register 59(133): 35680-35681, July 13, 1994.
USFWS (U.S. Fish and Wildlife Service). 2020. National wetlands inventory wetlands mapper
[online database]. U.S. Department of the Interior, Fish and Wildlife Service, Washington,
D.C. Available at: https://www.fws.gov/wetlands/Data/Mapper.html (accessed on February
24, 2020).
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