HomeMy WebLinkAboutSWP272264(16) S E PA
1 c�Py
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1 Riparian and Instream Habitat Report
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1
Maplewood Creek Fish Passage
Channel Project
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1 July 199
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1 Prepared for
1 City of Renton, Washington
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1
Prepared by
HARZA
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1
Riparian and Instream Habitat Report
1
1
Maplewood Creek Fish Passage
1
Channel Project
July 1995
Prepared for
' City of Renton, Washington
1
Prepared by
HARZA
1
Riparian and Instream Habitat Report
TABLE OF CONTENTS
1.0 Introduction............................................................................1
2.0 Existing Conditions................. 1
2.1 Upstream and Downstream Passage .........................................................2
2.2 Hydrologic/Hydraulic Conditions............................................................3
2.3 Habitat Quality ..................................................................................3
3.0 Design Criteria ........................................................................5
4.0 Proposed Enhancement Measures ................................................7
i4.1 Instream Habitat Structures ...................................................................7
4.1.1 Channel A Section.......................................................................7
4.1.2 Channel B Sections ........................... .8
4.1.3 Channel C Sections (Fairway Crossings)............................................8
4.1.4 Channel D Sections (Fish Ladders)...................................................9
4.2 Streambank Plantings...........................................................................9
5.0 Expected Benefits................................................................... 10
5.1 Hydrologic/Hydraulic Conditions.......................................................... 10
5.2 Habitat Quantity and Quality................................................................ 11
6.0 Literature Cited..................................................................... 12
Figures
1. Low-Flow Fish Passage Channel Conceptual Planting Design Plan View
2. Low-Flow Fish Passage Channel Section View of Channel Design
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Riparian and Instream Habitat Report
MAPLEWOOD CREEK FISH PASSAGE
CHANNEL
' Riparian and Instream Habitat Report
1.0 Introduction
The Maplewood Creek Basin Plan ( draft Parametrix, 1989) was developed primarily to
address flood control, water quality, and aquatic habitat concerns. In addition to outlining
' major policy goals, the Plan identified ten specific projects to stabilize streambanks, reduce
erosion and sedimentation, manage stormwater, and enhance habitat for fish and wildlife. The
Maplewood Creek Fish Passage Channel, proposed for the portion of the creek traversing
Maplewood Golf Course, is one of the projects intended to improve flood conveyance and fish
habitat along the main channel of Maplewood Creek.
The Fish Passage Channel is one of three elements aimed at improving conditions on
( Maplewood Creek. The other two elements include a fish ladder recently constructed by the
Washington Department of Transportation (WSDOT) at Maplewood Creek's confluence with
the Cedar River; and improvements to the existing sediment retention basin just upstream of
the Project reach. This report focuses on riparian and instream habitat. Existing conditions
are described and measures for enhancement are proposed. In addition, this report serves as a
basis for the plan to mitigate wetland impacts associated with construction of improvements to
the existing sediment basins, and diversion of water from the existing channel for Maplewood
Creek.
2.0 Existing Conditions
According to the Cedar River Current and Future Conditions Report (King County
1993), coho (Oncorhyncus kisutch) may use Maplewood Creek as far as RM 0.4, and cutthroat
' trout (O. clarki) up to RM 1.0. Sockeye (O. nerka), chinook (O. tshawytscha), steelhead (O.
mykiss), and Dolly Varden (Salvelinus spp.) are present in the Cedar River and were probably
present in the creek, also, prior to construction of the railroad, highway and 72-inch culvert,
and the golf course. Other fish species likely to occur in the Project reach under current
conditions include speckled dace (Rhinichyths osculus), three-spine stickleback (Gasterosteus
' aculeatus) and sculpin (Cottus spp.).
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The principal factors now affecting fish habitat and fish populations in Maplewood
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Creek are: 1) blockages to upstream and downstream fish passage; 2) hydrologic/hydraulic
conditions that cause extreme winter floods and low summer flows; and 3) low-quality aquatic
' habitat lacking structural diversity.
' 2.1 Upstream and Downstream Passage
In the Project reach, Maplewood Creek has been channelized to run in a straight course
from the existing sediment ponds south through the Maplewood Golf Course to State Route
169. Before the widening of SR 169, the creek crossed south under the highway via a 165-
foot long, 42-inch diameter steel culvert, then turned west and traveled through a 1,000-foot
long, 72-inch diameter RCP culvert buried next to the railroad bed before entering the Cedar
River at RM 3.4. During widening of the highway, the 42-inch diameter culvert was replaced
with two 8-foot by 4-foot box culverts. The creek still uses the 72-inch culvert to reach the
Cedar River. Following construction of the low-flow channel, this system will continue to
handle high flows in the creek that are diverted around the low-flow channel, but baffles
installed to facilitate upstream fish migration within the 72-inch diameter culvert will be
removed. Nominal capacity of this system under current conditions is approximately 150 cfs
(w/baffles removed). Note: with extreme flooding of the Cedar River, the capacity of this
system is probably reduced to approximately 100 cfs.
The culvert system blocks Maplewood Creek to anadromous fish except during periods
of high flow in the Cedar River. The culvert system will be bypassed upon completion of the
Fish Passage Channel, when the new channel will be connected to the new WSDOT fish
ladder by removing ecology blocks that were placed at the structure's headwall.
Fish passage is blocked at the upstream end of the Project reach by the existing
sediment pond and upper concrete dam. These structures will be removed as part of a project
to expand and improve sediment retention capabilities. The sediment basin will be enlarged
and improved by adding a fishway outlet and a flow diversion structure. This project is
described in detail in the Maplewood Creek Sedimentation Basin Reconstruction and
' Improvement Project Phase I Design Report (Harza Northwest 1994). Because fish passage
concerns have already been addressed in other reports, they will not be considered further in
this report.
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2.2 Hydrologic/Hydraulic Conditions
Continuous HSPF simulations of over 42 years (October 1948 - June 1991) of hourly
stream flows in Maplewood Creek were conducted by King County Surface Water
Management staff, to characterize flow regimes under various basin development conditions.
Average annual simulated flows for Maplewood Creek are 3.20 and 3.72 cfs under the current
' and the future basin land use conditions, respectively (King county 1993). Flows are lowest
from July through October and highest from December through March. Modeled daily flows
indicate that flows exceed 20 cfs from 5 to 7 days per year, primarily during the winter (Harza
tNorthwest 1994). The peak flow for the 2-year, 24-hour storm event was 118 cfs and 173 cfs
under the existing and the future land use conditions, respectively.
The existing channel does not provide adequate flood conveyance for flows over
150(±) cfs, and portions of the golf course can be flooded if flows exceed the two- to ten-year
flood magnitude. In addition, Cedar River flooding further reduces the capacity of the existing
system by creating a backwater at the downstream end of the 72-inch culvert. When capacity
of the culvert system is reduced, water from Maplewood Creek may flood the golf course.
Extreme flooding is generally detrimental to production of juvenile salmonids, and production
of coho smolts has been directly correlated to low summer flows of tributary streams in the
Puget Sound region (Baranski 1989).
2.3 Habitat Quality
Habitat quality in the canyon reach of Maplewood Creek, above the existing irrigation
ponds, was surveyed by King County Surface Water Management staff in 1991-1992. The
Cedar River Current and Future Conditions Report (1993) describes habitat on top of the
plateau as being degraded and fragmented by development. The upper portion of the canyon
' reach (RM 0.75-1.38) is described as "heavily affected by channel scour, a naturally unstable
geologic condition, and lateral bank sliding". The pool:riffle ratio was estimated to be 30:70.
The number of pieces of large woody debris per channel width was estimated at 0.7, in
comparison to an average of 2-2.7 in unmanaged small streams (Peterson 1992).
The lower portion of the canyon reach (RM 0.5-0.75) was described as containing
some good habitat, although it is affected by sedimentation and high flows. The pool:riffle
ratio was similar, approximately 30:70, but the number of pieces of large woody debris per
channel width was estimated at 1.7.
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Fish habitat in the stream segment through the golf course was qualitatively surveyed
during site visits on March 4 and April 12, 1995. This reach extends approximately 1,250
feet from the sediment pond to the point at which it enters the 42" culvert. Length of the
culverted segment is approximately 1,000 feet. The culverted segment is assumed to provide
no fish habitat.
Gradient through the upper 300 feet of channel is steepest (approximately 10 percent).
The channel is also narrow and confined through this reach, as it traverses the parking lot
adjacent to the clubhouse. In this vicinity, the wetted width is approximately 2 feet. The
substrate is clean gravel from 1/2 to 2" diameter. Habitat consists entirely of runs. No woody
debris or other instream habitat structure is present. Banks are vertical and overgrown with
dense Himalayan blackberry (Rubus discolor). This strip of vegetation, while narrow, does
provide shade and cover along the stream.
Length of the open channel as the stream crosses the golf course is approximately 950
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feet, with a gradient from 2 to 4 percent. This section of the creek was channelized and
straightened in the past, and is disturbed due to excavation, sediment removal, and mowing.
The wetted width varies, with short stretches 2 feet wide, increasing to as much as 12 feet
where gravel deposition has occurred. The substrate is also variable; patches of clean gravel
alternate with areas of silt deposition. Habitat is predominantly riffles and glides, with small
cascades and pools at the downstream ends of culverts installed under cart paths. The
pool:riffle ratio is approximately 20:80. No large woody debris is present in the creek or
along the banks. A few boulders are present. Vegetation along this reach is predominantly
grasses, with scattered soft rush (Juncus effusus), small-fruited bulrush (Scirpus microcarpus),
and patches of smartweed (Polygonum spp.) and creeping buttercup (Ranunculus repens). A
few cottonwood (Populus trichocarpa) seedlings, alder (Alnus rubra) saplings and blackberry
were also noted during site visits. Bank slopes vary from vertical to 3:1 and appear stable
along most of the creek, although small areas of slumping and erosion were noted. Bank soils
appear to be mixed sandy, loam and clay, likely as a result of excavation and grading during
golf course construction and channelization. Quarry spalls and some larger materials (12-18"
angular rip-rap) have been placed as erosion control at several points along the bank; some of
this has fallen into the channel.
Water quality data discussed in the Cedar River Current and Future Conditions Report
(King County 1993) indicate that "significantly high" levels of suspended solids, turbidity,
total phosphorus and fecal coliform bacteria were documented during two storm events.
1 Although data were collected above the irrigation ponds, similar levels could be expected in
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' the golf course reach of Maplewood Creek. Golf course maintenance
g p t nance requires use of
fertilizers, fungicides and pesticides. These are applied according to EPA guidelines, but
could affect overall water quality and nutrient conditions. Although water quality has not been
1 comprehensively studied, the presence of cutthroat in the upper watershed indicates that water
quality is at least adequate (Hughes and Gammon 1987).
In summary, the existing channel may meet the minimum requirements of sockeye,
coho and cutthroat, which tolerate a wider range of environmental conditions than other
' salmonids (Wydoski and Whitney 1979), but it is far from ideal. It has the relatively
featureless characteristics of a ditch, without the instream diversity, substrate, or cover needed
for spawning and rearing. The current hydrologic regime, including scouring flood flows in
the winter, and extremely low flows during the summer, provide poor support for fish
production. These habitat elements can be substantially improved by construction of the Fish
Passage Channel.
3.0 Design Criteria
Design criteria were based primarily on the hydraulic capacity needed to prevent
flooding and the habitat characteristics necessary to promote production of juvenile coho
salmon and cutthroat trout. Golf course maintenance requirements, playability and aesthetics
were also integrated into the plan. For example, riparian vegetation is designed to provide the
stem densities needed to slow flood waters. It will have the added benefits of stabilizing banks
and preventing erosion, provide overhanging shade and cover for fish, and will add texture
and color to the existing landscape. Increasing channel sinuosity will provide a more natural-
appearing stream course than the existing ditch, and will also provide more habitat area and
diversity for fish. Design criteria relating to fish habitat are discussed below.
' Sockeye, coho and cutthroat are the species most likely to utilize Maplewood Creek,
and are most likely to benefit from habitat enhancement measures in the Fish Passage Channel.
.Their habitat preferences for adults are similar (Wydoski and Whitney 1979). All three
species require riffle habitat for spawning, with a gravel substrate that is clean, stable, and
well-oxygenated. Pools provide cover for spawning fish and feeding and rearing areas for
juvenile coho and cutthroat fish. Consequently, it is important for pools and riffles to be
adjacent for them to function best for fish.
Sockeye and coho salmon generally spawn from September through December, burying
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their eggs in streambed gravel, often in pool tailouts and riffles. Sockeye fry emerge from the
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gravel between February and May and then immediately outmigrate to Lake Washington.
Coho fry emerge from the gravel in April or May and remain in the freshwater stream for at
least one year before outmigrating to saltwater. Coho juveniles congregate in slow pools,
' feeding primarily on aquatic insects such as caddisflies, mayflies, and stoneflies. Other prey
items include worms, fish eggs, terrestrial insects, and smaller fish.
Cutthroat trout migrate into spawning areas during October, November, and
December, but do not spawn until January, February, and March. Fry emerge in June or
' July. Unlike coho and sockeye, cutthroat trout may remain in freshwater streams their entire
life, or may outmigrate to larger water bodies (e.g. Lake Washington or the ocean) for periods
of several months and then return to their "home" stream for spawning. Juveniles and adults
feed primarily on aquatic insects, but also eat terrestrial insects, crayfish, salamanders, fish
eggs, and smaller fish.
Habitat suitabilitycriteria in terms of water depth and velocity is not well defined for
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streams as small as Maplewood Creek, so the following descriptions are general in nature and
relate to the size of fish most likely to access and use this particular stream. For spawning,
sockeye and coho salmon use gravel 1/4 to 3 inches in diameter located in water depths of 0.5
to 2.0 ft with relatively fast velocity of 1 to 3 feet per second (fps). They also require pools
deeper than 1 ft to hold in prior to spawning. Cutthroat trout are smaller than adult coho and
1 sockeye, and spawn in smaller gravel with less depth (0.3 to 1.0 ft) and velocity (0.5 to 1.5
fps).
Juvenile coho salmon rear in scoured stream margins and pools with depths of 0.5 to
5.0 feet and water velocity of 0.1 to 1.0 fps. They frequently rear in ponds, and require
refuge habitats (e.g. eddies created by boulders and logs, ponds, and alcove pools) to survive
winter floods. Juvenile and adult cutthroat trout use a variety of habitats with water depths 0.5
to 5.0 ft deep and velocities of 0.5 to 2 fps.
Both coho and cutthroat species require riffles to produce the aquatic insects they prey
on. Consequently, a pattern of adjacent riffles and pools is beneficial, with open canopy over
riffles allowing sunlight to increase production and overhanging canopy over pools to provide
cover from sunlight and predators. Summer water temperatures of 12 to 16 degrees C with
dissolved oxygen concentration of 5 mg/l or greater is best for production of both species.
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4.0 Proposed Enhancement Measures
The Fish Passage Channel will be excavated through the golf course and designed to
replicate a natural stream channel as closely as possible (Figure 1). It will contain all flow
' from Maplewood Creek up to 20 cfs, and will be designed for a maximum flow of 45 cfs.
Higher flows during runoff and flood conditions will be directed to the existing ditch or a
' reconfigured high-flow channel.
The channel design includes three typical cross-sections (Figure 2): 1) trapezoidal
streambed with log-drop structures, 2) trapezoidal streambed with overbank floodway, and 3)
half-round culvert. In addition, two reaches of the channel which are 5-10 percent gradient
will require laddering to allow upstream movement of fish. In reaches that are from 2-5
percent gradient, the cross-section will be trapezoidal in shape and provided with log-drop
structures (Channel A). This section will pass high flows during the winter, while maintaining
as much depth as possible during low flows in the summer. No overbank floodway is needed
at this slope. In the lower-gradient reaches (0-2 percent gradient), the channel cross-section
will be generally trapezoidal with overbank floodway (Channel B) to provide adequate water
depth for fish during the summer, and flood conveyance during high-flow events. In places
where the channel crosses golf course fairways and/or utilities, the channel cross section will
consist of a 1/2 round culvert (Channel C), to minimize the width of the cut and maximize the
stability of the crossing. Sections of fish ladder will be rectangular in shape. Intermittent
bridge crossings (up to 7) will be constructed over the channel to facilitate the circulation of
golfers and maintenance vehicles around the golf course.
4.1 Instream Habitat Structures
4.1.1 Channel A Section
Approximately 430 feet of the new channel will have a 2-5 percent gradient. Log drop
1 structures will be placed at 20- to 45-foot intervals through this reach. Log drop structures are
intended to reduce water velocities, create slow pools, stabilize riffles, and provide cover and
resting habitat for fish moving upstream. Logs should be sufficient in length to span the
stream and be well-anchored into both banks. A 1- to 2-foot layer of rip-rap with cobble or
quarry spall bedding should be placed as protective backfill for anchor protection on each
bank. Logs should be 24 inches in diameter; if smaller-diameter logs are used, two logs
should be cabled together. A notch 4 inches deep and 12 inches wide should be cut into the
top log to concentrate flow during low-flow periods of the year. Clay lining or geomembrane
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fabric will be provided for channel sections A and B, forming an impervious underbedding for
1 the stream to minimize seepage losses during low flows. Cobble or quarry spalls should also
be placed just below each log drop to protect the clay lining as scour pools form. Immediately
upstream of log-drop structures, washed gravel of 1/4 to 6 inches in diameter will be added so
that the depth of gravel is about 1 foot, suitable for coho and sockeye salmon spawning. Log-
drop structures will be placed in relatively straight sections of stream to avoid bank erosion
from resulting flow patterns.
4.1.2 Channel B Sections
Approximately 1,000 feet of the new channel will have a trapezoidal cross-section.
Overall gradients will be from 0 to 2 percent. Log-drop weirs and triangle wing deflectors
will be installed in this channel type at about 12 sites about 100 feet apart to increase pool
depth, provide structural cover, and increase low-flow thalweg depth. Because of the low
gradient, washed gravel added to the upstream side of log-drop structures will be small (1/4 to
3 inches in diameter) to create optimum riffles for spawning and aquatic insect production. In
addition, single boulders 12 to 24 inches in diameter will be placed at about 30 sites in the
channel to provide islands of in-channel cover.
Wing deflectors will be placed immediately upstream of several of the bends in the
channel so that the thalweg is directed into the scour pool at the apex of the bend. Deflectors
will be built in the plan-view shape of a solid triangle to minimize back-cutting during high
flows, using boulders 1 to 3 ft in diameter and cobbles 6 to 12 inches in diameter. The
opposite bank will be stabilized with vegetation, boulder bank revetments, or log cover
structures as necessary.
4.1.3 Channel C Sections (Fairway Crossings)
These sections comprise a total of about 260 feet of channel located in three places.
' Where the stream crosses each fairway, lengths of 4-foot diameter half-round CMP culvert
will be installed to contain the flow, prevent stream meandering, and reduce the width of the
cross-sections so that interference with golf course play and/or underground utilities is
minimized. Washed gravel 1/2 to 2-inch-diameter will be added to provide a natural substrate
in the culverts. Culvert slope will be less than 2 percent so that water velocity will be
negotiable by juvenile fish.
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4.1 4 Channel D Sections (Fish Ladders)
' Two short reaches of the creek will be steep enough in gradient (approximately 10
percent) to require laddering. Immediately below the sediment pond, a length of channel
approximately 90 feet long will be laddered. A second length of channel 50 feet long,
adjacent to the existing clubhouse, will also be laddered. The pool and weir design will be
' constructed of concrete, with v-shaped 8" deep weirs at 6-8' intervals through each of these
reaches. Pools will be 3.5 feet deep between the weirs at normal flows. Construction design
will be similar to plans, sections and details for the WSDOT fish ladders and the fishway
outlet shown in the Maplewood Creek Sedimentation Basin Reconstruction and Improvement
Project Phase 1 Design Report (Harza Northwest 1994).
4.2 Streambank Plantings
The upper end of the Project area below the proposed sediment pond and adjacent to
the existing clubhouse marks a transition in both topography and landscaping. Above the
' project, hillslopes are naturally vegetated. Within the golf course, and along the project
reaches, the site is developed for recreation and intensive human activity. A mix of native
trees and tall shrubs will be planted along the channel which will provide a visual transition
from the steep, forested hillside to the gently-sloping turf of the fairways. Live-staking the
' channel banks with cuttings of native willow (Salix lasiandra, S. scouleri) and red-osier
dogwood (Cornus stolonifera) is recommended in this vicinity, and could also be used between
Fairways 1 and 2, where vegetation height is not a concern. These species are well-adapted to
local conditions, start well from cuttings, and require little or no maintenance. Willow and
dogwood provide attractive color year-round. Other benefits include shallow, laterally-
spreading root systems that hold soils well, growth forms that provide overhanging shade and
cover for fish, and low cost of planting. Plantings will be concentrated in areas of log and
boulder structures and the pools they create. Cuttings may be available at low cost through
King County SWM salvage projects or on city-owned lands in the Cedar River basin.
Hydroseeding with a mix of low-growing grass and wildflowers will provide rapid soil
coverage and reduce erosion while the cuttings are starting out.
Low-growing native and hybrid willows (Salix brachycarpa, S. caprea) and hybrid
species of dogwood (Cornus sericea 'Baileyi', Cornus alba 'Siberica') and pyramid spirea
(Spiraea x pyramidata) are recommended along Channel A and Channel B sections in areas
where golf course design criteria make spreading trees or tall shrubs unacceptable. These
species reach only 2-6 feet in height, and would be compatible with the existing landscaping
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and maintenance. With taller species being planted below the existing ground level, they
would not obstruct views along the fairways and greens, and will also help to provide shade
and bank stability. Species selected for planting will depend, in part, on availability. They
are not always available as cuttings, and may be planted as 18"-24" rootstock on 3' centers.
Plantings along the laddered sections of the channel must be tolerant of drier conditions
' than those species listed above. Suggested native plants include groupings of vine maple (Ater
circinatum), Oregon grape (Berberis nervosa) and salal (Gaultheria shallon), and groupings of
Pacific ninebark (Physocarpus capitatus), mock orange (Philadelphus lewisii) and black
twinberry (Lonicera involucrata) planted as 34' rooted stock on 3' centers. The taller of
these species will provide overhanging shade, while dense plantings of lower-growing species
will help to isolate the fishway from golf course play and from the view of golfers.
Turf grasses are recommended for the margins of Channel C Typical Cross-Sections, to
minimize the visual impact of the fish channel across the fairways. Use of turf grasses will
' also simplify maintenance of the fairways.
Final selection of species and locations and density of plantings will be closely
' coordinated with landscaping that is currently underway at the golf course. Existing cedar,
locust and fir trees will be retained. Some small-diameter fir trees may be moved to allow
construction, and replanted where they will provide shade to the stream.
5.0 Expected Benefits
Construction of the Fish Passage Channel is expected to significantly improve habitat
for fish in Maplewood Creek. Benefits are difficult to quantify, however, because of the
number of variables involved, including upstream water uses, annual weather patterns, and
' escapement of spawners to utilize the new habitat. Consequently, the benefits are described
generally in terms of changes to physical channel features.
' 5.1 H drolo ic/H draulic Conditions
y g y
The Fish Passage Channel will be capable of passing up to 45 cfs, which will improve
flood conveyance through the golf course. Routing of higher flows through the existing
channel will protect the Fish Passage Channel from scouring floods. In the new channel, the
increased length and reduced gradient will result in slower overall water velocity and reduced
energy of water, consequently erosion potential will be reduced. In-channel structures will
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help to concentrate the summer low flow such that surface flow should remain continuous. In
' addition, these structures will provide a diversity of water velocities throughout the channel to
accommodate all lifestages of salmonids and produce aesthetically pleasing pools and riffles
' and a natural-looking streamcourse. Vegetation will also serve to reduce stream energy,
stabilize banks, and add to the natural appearance of the channel.
' 5.2 Habitat Quantity and Quality
Construction of the new low-flow channel, together with the WSDOT ladder at the
Cedar River and planned passage facilities at the sedimentation pond will open approximately
' 3.4 miles of Maplewood Creek that are currently blocked to anadromous fish, and add
approximately 0.4 miles of habitat through the golf course.
' The increased sinuosity and length of open channel will provide more habitat area for
fish and aquatic organisms (Ministry of Environment 1980). In-channel features and the
' resulting pools, riffles, and cover components will greatly increase the quality of habitat for all
stream dwelling life stages of sockeye and coho salmon and cutthroat trout.
Addition of gravel will increase the amount of suitable spawning habitat and the
production of periphyton and aquatic insects. In addition to increasing the diversity of the
benthic community, periphyton are also important in reducing phosphorus levels in streams
(Davis et al. 1990). The compressed thalweg will increase the depth of water during low flow
conditions to facilitate movement of adult and juvenile fish. Vegetation will stabilize the banks
from erosion during high flows, filter suspended sediments, provide shade to moderate stream
temperatures and light levels, add nutrients to the stream in the form of leaf litter and
terrestrial insects, and provide cover for fish from predators (Bisson et al. 1992).
' Accurate estimates of production or population potential require intensive study of
individual streams. No investigations of this type have been conducted in the Maplewood
' system. As an indicator of coho production, studies of coho in 10 Pacific Northwest streams
showed mean annual production of coho smolts as 0.31/m (Baranski 1989). Numbers of
cutthroat (all ages) in one Olympic Peninsula stream were estimated five times in a two-year
' period, and averaged 0.30/m2 (June 1981); however no coho were present in the study stream.
In situations where both coho and cutthroat are present, cutthroat numbers may be somewhat
lower. Sockeye production is estimated in terms of fry outmigrating from the stream, and
would be several hundred sockeye fry per spawning pair.
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6.0 Literature Cited
' Baranski, C. 1989. Coho smolt production in ten Puget Sound streams. Technical Report
99, Washington Dept. of Fisheries. 29pp.
' Bisson, P.A., Quinn, T.P., Reeves, G.H. and S.V. Gregory. 1992. Best management
practices, cumulative effects, and long-terms trends in fish abundance in Pacific
Northwest river systems. Pages 189-232 in: Naiman, R.J., ed. Watershed
Management: Balancing Sustainability and Environmental Change. Springer-Verlag,
' New York, New York.
City of Renton. 1989. Comprehensive Stormwater Plan. Maplewood Creek Basin Plan.
Public Works Department, Stormwater Utility Division.
Davis, L.S., J.P. Hoffman and P.W. Cook. 1990. Production and nutrient accumulation by
periphyton in a wastewater treatment facility. J. Phycol. 26:617-623.
Gray, D.H. and A.T. Leiser. 1982. Biotechnical Slope Protection and Erosion Control. Van
Nostrand Rheinhold, New York.
Hughes, R.M. and J.R. Gammon. 1987. Longitudinal changes in fish assemblages and water
quality in the Willamette River, Oregon. Trans. Am. Fish. Society. 116:196-209.
June, J.A. 1981. Life history and habitat utilization of cutthroat trout (Salmo clarki) in a
headwater stream on the Olympic Peninsula, Washington. M.S. Thesis, University of
Washington.
King County Department of Public Works. 1993. Cedar River Current and Future
Conditions Report. Surface Water Management Division.
eKing County Department of Public Works. 1993b. Guidelines for Bank Stabilization
Projects. Surface Water Management Division.
' Ministry of Environment. 1980. Stream Enhancement Guide. Government of Canada,
Fisheries and Oceans and Province of British Columbia, Ministry of Environment.
Wydoski, R.S. and R.R. Whitney. 1979. Inland Fishes of Washington. University of
Washington Press, Seattle and London.
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' Maplewood Creek Fish Passage Channel Page t2
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Riparian and Instream Habitat Report
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Seamen Porto I
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Figure 1
Low-Flow Fish Passage Channel
Conceptual Planting Design Plan View
Maplewood Creek Fish Passage Channel
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Riparian and Instream Habitat Report
EXIST GRADE
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Figure 2
Low-Flow Fish Passage Channel
Section View of Channel Design
Maplewood Creek Fish Passage Channel
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