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APPENDIX A
DATA SOURCES
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NATURAL SYSTEMS DESIGN | April 28, 2021
DOSEWALLIPS RESILIENCY PLAN: DATA SOURCES APPENDIX
The following data sources were utilized during the development of the Dosewallips Resiliency Plan:
DATA TYPE DATE SOURCE NOTES
Topographic Data
2018 bare-earth LiDAR DEM 2018
WA DNR
LiDAR
portal
Collected on 10/6/2017 and
7/22/2018
2018 highest hit LiDAR DSM 2018
WA DNR
LiDAR
portal
Collected on 10/6/2017 and
7/22/2018
2018 Relative Elevation Model 2018 This study Developed by NSD using 2018
bare-earth Lidar DEM
Aerial Imagery
National Agricultural Imagery Program (NAIP)
2005 NAIP 2005 NRCS data
portal
2011 NAIP 2011 NRCS data
portal
2017 NAIP 2017 NRCS data
portal
2019 NAIP 2019 NRCS data
portal
Other Imagery
1939 Aerial Single Pane 1939 USGS Earth
Explorer
1951 Aerial Single Pane 1951 USGS Earth
Explorer
1968 Aerial Single Pane 1968 USGS Earth
Explorer
1980 imagery 1980 USGS Earth
Explorer
1991 imagery 1991 USGS Earth
Explorer
1994 imagery 1994 USGS Earth
Explorer
Geology/Geomorphology
1:24,000 surface geology WA DNR
Flood and Erosion Risk Assessments
Channel Migration Zone mapping 2004
Jefferson
County GIS
Portal;
Klawon,
2004
Used as comparison for updated
CMZ as part of this study
FEMA Flood zones
2019 Flood
Insurance
Study
FEMA
JEFFERSON COUNTY PUBLIC HEALTH DEPARTMENT DOSEWALLIPS POWERLINES/LAZY C RESILIENCY PLAN – DATA SOURCES APPENDIX
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NATURAL SYSTEMS DESIGN | April 28, 2021
DATA TYPE DATE SOURCE NOTES
Land-use and ownership
Jefferson County Parcel Layer
Jefferson
County GIS
Portal
Fish use
Statewide Washington Integrated
Fish Distribution
Washington
Geospatial
Data Portal
Dosewallips Habitat Assessment
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DOSEWALLIPS RESILIENCY PLAN Habitat Assessment
Prepared for:
Natural Systems Design
Prepared by:
Shelby Burgess and Phil Roni
Cramer Fish Sciences Watershed Sciences Lab 1125 12th Avenue NW, Suite B-1 Issaquah, WA 98027
Report created: November 2020
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List of Figures
Figure 1. Instantaneous flow (cfs) data at USGS Gage 1205400 – Duckabush River near Brinnon, WA
recorded and reported by USGS. No gage data is available for the Dosewallips, but the Duckabush is
located nearby and similar in size and can be used as a proxy for flow information (Labbe et al. 2005). The Dosewallips was surveyed October 9th. .............................................................................. 2
Figure 2. Overview of the Dosewallips River survey area with survey reaches of interest (Labbe et al. 2005) and start and end of survey locations. ......................................................................................... 3
Figure 3. The percent of wetted habitat area by habitat unit, channel type, and reach. Braid and side-
channel habitats were surveyed as time allowed and were not a full census of habitats. ..................... 8
Figure 4. Pool count by pool size, channel type, and reach. Pool size was classified by using wetted area and residual pool depth (Pleus et al. 1999). Braid and side-channel habitats were surveyed as time allowed and were not a full census of habitats. .................................................................................... 8
Figure 5. Pool count by pool forming feature, channel type, and reach. Braid and side-channel habitats
were surveyed as time allowed and were not a full census of habitats. ................................................ 9
Figure 6. Overview of the Lazy C - Upstream Reach with results from CFS habitat surveys. All wetted braids present in this reach were surveyed. There were no side channels in this reach. Adult coho and chum were present in this reach, and one spawning location was documented. ................................ 11
Figure 7. Facing upstream, the small braid surveyed in the Lazy C – Upstream Reach. The braid was
shallow, predominantly plain bed, and lacked instream cover and habitat complexity and therefore does not represent high quality habitat for rearing juveniles. ............................................................. 12
Figure 8. Substrate composition from visual estimates for the Lazy C – Upstream Reach by unit and channel type. ....................................................................................................................................... 12
Figure 9. Overview of The Lazy C - Downstream Reach with results from CFS habitat surveys. All
wetted braid and side channels were surveyed in this reach. Adult coho and chum were present in this reach, and one spawning location was documented..................................................................... 14
Figure 10. Facing downstream, an example of a pool forming log jam adjacent to the Lazy C development at the downstream end of the Lazy C – Downstream Reach. The Lazy C development
confines lateral channel movement on the left bank and the lack of riparian vegetation and eroding
banks do not provide adequate cover or slow water habitats and present a restoration opportunity in this reach. ............................................................................................................................................ 15
Figure 11. Substrate composition from visual estimates for the Lazy C – Downstream Reach by unit and channel type. ....................................................................................................................................... 15
Figure 12. Facing downstream, the surveyed side channel departs on river right. The side channel
provides rearing habitat for juvenile salmonids but lacks stable wood. ............................................. 16
Figure 13. Overview of the Powerlines Reach with the results from the CFS habitat surveys. Braids and side channels were surveyed as time allowed and were not a full census. Mainstem diversion locations of unsurveyed wetted braids and side channels were identified during surveys and general
channel locations were mapped using the aerial imagery in GIS. ...................................................... 18
Figure 14. Facing upstream, an unsurveyed braid on river right and surveyed channel on river left in the Powerlines Reach. This highlights the sinuous and unconfined braids of the Powerlines Reach. ..... 19
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Figure 15. Substrate composition from visual estimates for the Powerlines Reach by unit and channel
type. Braid and side-channel habitats were surveyed as time allowed and were not a full census of habitats. ............................................................................................................................................... 19
Figure 16. Facing downstream, an example of functional log jams in the surveyed side channel in the Powerlines Reach. ............................................................................................................................... 20
List of Tables
Table 1. Pool size classifications derived from Pleus et al. (1999) and used in Labbe et al. (2005), converted to feet. ................................................................................................................................... 4
Table 2. Overview mainstem habitats surveyed in the Dosewallips River Study Area by reach. The count of observed units is n; length (feet) and area (feet2) are totals; width (feet) is the average unit width;
depth is the average unit depth (feet) for all units except for pools for which the average residual pool depth (feet) is reported. Braid and side channel habitats were surveyed as time allowed and were not a full census of habitats. Na indicates the habitat did not exist, (-) indicates the habitat did exist but was not surveyed. ................................................................................................................... 6
Table 3. Pool counts, pool frequency (pools per mile), total pool area, the proportion of area in pools,
pool spacing (channel widths per pool) (Montgomery et al. 1995), and the average residual pool
depth for all channel types and reaches for the Dosewallips River mainstem. Braid and side-channel habitats were surveyed as time allowed and were not a full census of habitats. Na indicates the habitat did not exist, (-) indicates the habitat did exist but was not surveyed. ..................................... 6
Table 4. Percent substrate composition from visible observation for units, channel types, and reaches.
Braid and side-channel habitats were surveyed as time allowed and were not a full census of habitats. Na indicates the habitat did not exist, (-) indicates the habitat did exist but was not surveyed. ............................................................................................................................................... 7
Table 5: Data collected at the habitat unit level for habitat surveys for mainstem habitats. .................... 22
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INTRODUCTION
The Dosewallips River supports nine salmonid and trout species, including the ESA listed Puget Sound
Fall Chinook Oncorhynchus tshawytscha and Hood Canal summer chum O. keta, and thus has been
identified as a restoration priority (Frissell et al. 2000; Labbe et al. 2005; WDFW & NWIFC 2014).
The Dosewallips historically supported large salmon runs and continues to be an important river for
distinct stocks of fall Chinook, summer and fall chum, and coho O. kisutch (Correa 2003). Disturbance in
the lower river below the canyon, from development and logging, has led to simplification, loss, or
degradation of natural habitats, and thus the Dosewallips has been identified for further evaluation and
restoration to benefit these species (Labbe et al. 2005). The runs of interest differ in their life histories and
use of key riverine habitats. Summer chum generally enter the river as adults in August or September,
spawn until October, and fry subsequently emerge in March and April and outmigrate quickly after. While
fall Chinook generally spawn in September through December and eggs incubate until January through
March. Juvenile fall Chinook rear in freshwater for a variable time, typically a few weeks to months, and
outmigrate anywhere between January and August. Coho also enter the river in the fall but generally
spawn in the winter and emerge in spring and rear for a full year. Providing adequate freshwater migration,
spawning, incubation, and rearing habitat is important for all of these species, however Chinook and coho
utilize rearing habitats more than summer chum (Correa 2003; Quinn 2018). All three species require
suitable sized gravel and cobble for spawning and rearing with low levels of fine sediment. Winter floods
which are exacerbated by the straightening and confinement of channels and disconnection from
floodplain habitats can also scour and damage redds and increase infiltration of fine sediment reducing
oxygen levels available to embryos (Quinn 2018). Additionally, salmonid rearing and spawning success
are low if adequate summer flows and water quality, channel complexity, slow water habitat, and off-
channel and floodplain connectivity, and healthy riparian forests providing large wood sources and cover
are not present (Ames et al. 2000). Overwinter rearing habitat is particularly important for juvenile coho
due to their extended stay in freshwater compared to Chinook and chum salmon.
The goal of this assessment was to complete habitat surveys of the Powerlines/Lazy C reach to support
the formation of conceptual designs to improve the channel migration zone function, enhance habitat, and
drive self-sustaining floodplain and in-channel processes for summer chum and Chinook salmon use.
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METHODS
Surveys were completed by Cramer Fish Sciences (CFS) and Natural Systems Design (NSD) on October
9th during low flow condition (81 cfs at USGS Gage 1205400 – Duckabush River; Figure 1) on the
mainstem of the Dosewallips River from downstream of the Rocky Brook Creek confluence and canyon
to upstream of Brinnon, Washington (Figure 2). The survey was conducted over one day and mainstem
habitats (main channels, braids, and side channels) connected with surface water flow at the time of the
survey were surveyed as time allowed. Wetted and dry side channels and braids not surveyed were
captured with photos and their diversion point from the mainstem was captured by GPS coordinates.
Figure 1. Instantaneous flow (cfs) data at USGS Gage 1205400 – Duckabush River near Brinnon, WA recorded and reported by USGS. No gage data is available for the Dosewallips, but the Duckabush is located nearby and similar in size and can be used as a proxy for flow information (Labbe et al. 2005). The Dosewallips was surveyed October 9th.
Mainstem surveys were completed moving downstream by boat. Reaches were determined by
geomorphology and land use (Labbe et al. 2005). Channel type was recorded as main channel, braid, or
side channel (Leopold and Wolman 1957). Habitat units were identified as pools (non-turbulent), riffles
(fast-turbulent), or glides (fast non-turbulent) (Bisson et al. 1982; Beechie et al. 2005; CHaMP 2016).
Pool type (e.g., plunge, scour, dam) and pool-forming feature were recorded for pool units (Bisson et al.
1982). Lengths and wetted widths were recorded in meters using a laser rangefinder. Depths were
recorded in meters at twenty-five and seventy-five percent of the unit length for riffle and glide units and
at maximum and tail depth for pool units. Pool size was classified based on residual pool depth and
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wetted pool area as extra small, small, medium, or large (Pleus et al. 1999; Labbe et al. 2005; Table 1).
All metric units were converted to English units in processing. Substrate composition was recorded as a
visual estimate of the percent covered by bedrock, boulders, cobble, gravel, sand, and fines. The GPS
coordinates of the top and the bottom of each dominant unit were recorded, GPS units were also used to
record tracks of the channels surveyed. Recorded data outputs are available in Appendix A.
Figure 2. Overview of the Dosewallips River survey area with survey reaches of interest (Labbe et al. 2005) and start and end of survey locations.
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Table 1. Pool size classifications derived from Pleus et al. (1999) and used in Labbe et al. (2005), converted to
feet.
Pool size class Area (ft2) Residual pool depth (ft)
Extra small - <1.3
Small 108-1066 >1.3
Medium 1067-10,753 >1.3
Large >10,754 >1.3
RESULTS
A total of 2.8 miles of mainstem habitat were surveyed in the Dosewallips River study area. This
included 2.3 miles of main channel, 0.2 miles of braided channel, and 0.4 miles of side-channel habitat
(Table 2). Additional braid and side-channel habitats wetted at the time of the survey were not surveyed
because of time constraints. Braids and side channels were infrequent or absent, respectively, in the
Lazy C – Upstream Reach, but were present in the Lazy – C Downstream and Powerlines reaches
(Figure 2).
Riffle habitat made up 52% of the total surveyed wetted area (Figure 3; Table 2). Pools made up 28% of
the surveyed habitat area and 34% of the channel length. The majority of mainstem pools were in the
large size class (Figure 4). Large wood, including jams and individual pieces, was identified as the most
frequent pool forming feature, followed by bedrock and meanders (Figure 5).
In main channel habitats, the Powerlines Reach had the highest total and proportion pool area of the
sureyed reaches (Figure 3; Table 3). The Lazy C – Upstream Reach had the lowest pool frequency
(pools per mile), as well as the least total and proportional pool area.
Substrate was predominantly composed of gravel or cobble in the mainstem and gravel and sand in the
side channels and braids that were surveyed (Table 4). Fines and bedrock were infrequent or absent
throughout the study area.
The reaches of the Dosewallips study area present a gradient of quality of salmon habitat, with the
Powerlines Reach demonstrating highest quality salmon rearing and spawning habitat with little
confinement, abundant side and braid channel habitat, and a large proportion of pool area, and the Lazy
C - Upstream Reach exhibiting relatively low quality habitat with confined banks, minimal off-channel
habitat, and low habitat complexity. Adult salmonids, including chum and coho, were observed
spawning and migrating throughout the study area, but were most frequent in the Powerlines Reach,
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with adult salmonid spawning activity only being observed in one location in the Lazy C - Downstream
and Upstream reaches respectively (Figure 6; Figure 9; Figure 13). Juvenile salmonids, including coho
were also observed utilizing side channel habitats. Restoration efforts focused on placement of large
wood to create slow water areas, encourage sediment deposition, and provide cover, bank enhancement
to reduce confinement and improve cover and slow water edge habitat, and floodplain reconnection to
create off-channel habitat would benefit rearing of coho and potentially fall Chinook, as well as enhance
spawning habitat for fall Chinook, coho, and chum. The Lazy C - Upstream Reach is the most confined,
contains the least spawning habitat, and appears to be most at risk for flooding and scour events and
therefore presents the most opportunity for restoration, however the Lazy C - Downstream Reach would
also benefit from enhancement actions.
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Table 2. Overview mainstem habitats surveyed in the Dosewallips River Study Area by reach. The count of
observed units is n; length (feet) and area (feet2) are totals; width (feet) is the average unit width; depth is the average unit depth (feet) for all units except for pools for which the average residual pool depth (feet) is reported. Braid and side channel habitats were surveyed as time allowed and were not a full census of habitats. Na indicates
the habitat did not exist, (-) indicates the habitat did exist but was not surveyed.
Main Channel Braid Side Channel
Reach Unit n Length (ft) Area (ft2) Width (ft) Depth (ft) n Length (ft) Area (ft2) Width (ft) Depth (ft) n Length (ft) Area (ft2) Width (ft) Depth (ft)
Lazy C -
Upstream
Glide 4 1,432 45,310 93 1.68 2 186 1,414 21 0.43 na na na na na
Pool 4 705 15,998 81 4.62 1 164 1,644 33 0.98 na na na na na
Riffle 5 2,264 70,899 101 1.38 2 100 832 28 0.26 na na na na na
Total 13 4,402 132,208 91 1.53 5 451 3,890 27 0.34 na na na na na
Lazy C - Downstream
Glide na na na na na 1 72 436 20 1.15 1 96 469 16 1.12
Pool 4 878 20,846 76 4.04 2 133 931 23 1.05 3 364 3,267 29 2.09
Riffle 2 1,460 47,717 105 1.30 1 139 1,291 31 0.79 3 332 1,820 17 1.04
Total 6 2,338 68,563 90 1.30 4 343 2,658 25 0.97 7 791 5,556 21 1.08
Powerlines
Glide 2 783 17,348 76 2.25 - - - - - 3 401 1,850 16 1.33
Pool 9 2,400 48,841 64 4.36 - - - - - 5 458 3,562 24 2.38
Riffle 8 2,062 51,468 77 1.25 - - - - - 4 450 2,713 19 0.82
Total 19 5,244 117,657 72 1.75 - - - - - 12 1,309 8,126 20 1.08
Total 38 11,985 318,427 84 1.57 9 794 6,548 26 0.656 19 2,100 13,682 20 1.08
Table 3. Pool counts, pool frequency (pools per mile), total pool area, the proportion of area in pools, pool
spacing (channel widths per pool) (Montgomery et al. 1995), and the average residual pool depth for all channel types and reaches for the Dosewallips River mainstem. Braid and side-channel habitats were surveyed as time allowed and were not a full census of habitats. Na indicates the habitat did not exist, (-) indicates the habitat did
exist but was not surveyed.
Reach Channel type Total pools Pools per mile Total pool area (ft2) Proportion pool area Pool spacing
Average
residual pool depth (ft)
Lazy C –
Upstream
Main Channel 4 4.8 15,998 0.12 13.7 4.62
Braid 1 11.7 1,644 0.42 13.8 0.98
Side Channel na na na na na na
Lazy C -Downstream
Main Channel 4 9.0 20,846 0.30 7.7 4.04
Braid 2 30.8 931 0.35 7.4 1.05
Side Channel 3 20.0 3,267 0.59 9.2 2.09
Powerlines
Main Channel 9 9.1 48,841 0.42 9.1 4.36
Braid - - - - - -
Side Channel 5 20.2 3,562 0.44 10.8 2.38
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Table 4. Percent substrate composition from visible observation for units, channel types, and reaches. Braid and
side-channel habitats were surveyed as time allowed and were not a full census of habitats. Na indicates the habitat did not exist, (-) indicates the habitat did exist but was not surveyed.
Reach Channel type Unit Bedrock Boulder Cobble Gravel Sand Fines
Lazy C - Upstream
Main Channel Glide 0 13 30 40 18 0 Pool 0 5 15 48 33 0 Riffle 0 18 42 28 12 0
Braid Glide 0 5 30 50 15 0 Pool 0 10 50 30 10 0 Riffle 0 0 35 50 15 0
Side Channel Glide na na na na na na Pool na na na na na na
Riffle na na na na na na
Total 0 8 34 41 17 0
Lazy C - Downstream
Main Channel
Glide na na na na na na
Pool 0 0 20 45 35 0
Riffle 0 5 40 45 10 0
Braid Glide 0 0 10 80 10 0 Pool 0 0 10 15 75 0 Riffle 0 0 20 50 30 0
Side Channel Glide 0 10 30 30 30 0 Pool 0 3 20 30 47 0
Riffle 0 3 13 47 37 0
Total 0 3 20 43 34 0
Powerlines
Main Channel Glide 0 0 40 45 15 0 Pool 2 1 20 40 37 0 Riffle 0 5 39 44 13 0
Braid Glide - - - - - - Pool - - - - - -
Riffle - - - - - -
Side Channel Glide 0 3 27 33 30 7 Pool 0 0 10 48 42 0
Riffle 0 0 43 45 13 0
Total 0 2 30 43 25 1
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Figure 3. The percent of wetted habitat area by habitat unit, channel type, and reach. Braid and side-channel habitats were surveyed as time allowed and were not a full census of habitats.
Figure 4. Pool count by pool size, channel type, and reach. Pool size was classified by using wetted area and
residual pool depth (Pleus et al. 1999). Braid and side-channel habitats were surveyed as time allowed and were not a full census of habitats.
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Figure 5. Pool count by pool forming feature, channel type, and reach. Braid and side-channel habitats were
surveyed as time allowed and were not a full census of habitats.
Lazy C – Upstream
The Lazy C - Upstream Reach spans from below the canyon and confluence of Rocky Brook Creek to
the upstream end of the Lazy C neighborhood (Figure 6). The left bank is influenced by residential
development and the right bank is confined by the valley wall. No side channels were present in this
reach, but one braid spanning 451 feet was present and surveyed (Figure 7). Riffles were the dominant
mainstem habitat unit and accounted for 53% of the wetted main channel area, followed by glides,
which accounted for 34% of the wetted main channel area (Figure 3; Table 2). Pools were the least
frequent and accounted for the least overall wetted area (12%) in this reach (Figure 4; Table 3), however
the pools that were present were deep and this reach had the highest average residual pool depth. The
Lazy C - Upstream Reach had the highest percentage of boulder substrate observed of the surveyed
reaches, however the reach substrate was predominantly gravel, cobble, and sand (Figure 6; Table 4).
The Lazy C – Upstream Reach had the lowest habitat unit complexity and least amount off-channel
habitat of the surveyed reaches. Adult coho and chum were present in this reach, but only one spawning
location was documented. The left bank adjacent to the Lazy C development has been modified and
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diked to protect residential development and the bank lacks complexity, consistent cover, and slow
water edge habitat (Correa 2003). Additionally, the reach was riffle and glide dominated and lacked off-
channel and mid channel slow water area for coho and fall Chinook rearing. Given the confinement and
lack of floodplain connectivity in this reach, this reach is subject to high winter flow velocities,
especially during spring and fall flooding events, which could scour and damage chum and fall Chinook
redds (Ames et al. 2000). The substrate of this reach was dominated by gravel and cobble, but boulders
were also frequent, which may limit chum and fall Chinook spawning habitat in this reach and is also
indicative of high velocities (Correa 2003). The lack of functional wood in this reach also indicated high
flow velocities and the lack of channel complexity to wrack wood. Stable large wood jams
accumulations were absent but are necessary to form stable pools and slow water areas and provide
cover for fall Chinook and coho rearing and holding, and to stabilize gravel for spawning habitat for
summer chum and other salmonids (Ames et al. 2000; Correa 2003). Many restoration opportunities
exist in this reach, in particular adding stable large wood to create slow water habitat and provide cover
and addressing the lack of off-channel and slow water edge habitat through bank and floodplain
enhancement actions. Floodplain habitat in the lower portion of the reach has largely been isolated due
to residential development, which likely limits potential restoration of floodplain habitat in this reach.
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Figure 6. Overview of the Lazy C - Upstream Reach with results from CFS habitat surveys. All wetted braids present in this reach were surveyed. There were no side channels in this reach. Adult coho and chum were present
in this reach, and one spawning location was documented.
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Figure 7. Facing upstream, the small braid surveyed in the Lazy C – Upstream Reach. The braid was shallow, predominantly plain bed, and lacked instream cover and habitat complexity and therefore does not represent high quality habitat for rearing juveniles.
Figure 8. Substrate composition from visual estimates for the Lazy C – Upstream Reach by unit and channel type.
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Lazy C – Downstream
The Lazy C - Downstream Reach spans the length of the Lazy C development (Figure 9; Table 2). The
left bank is confined by the residential development and a road. In the upper section of the reach, the
right bank is confined by the valley wall, but the lower section is unconfined to channel migration and
flooding. Riffles were the dominant main channel habitat unit in this reach and accounted for 62% of the
total habitat area (Figure 3). No glides were observed in the main channel of the Lazy C – Downstream
Reach. Pools accounted for the other 38% of the wetted channel area. Of the reaches surveyed, pool
spacing was the lowest in the main channel of this reach, with 7.7 channel widths per pool (Table 3).
The average residual pool depth for main channel pools in this reach was less than the other two reaches,
but there were three large pools and one medium pool documented (Figure 4). Mainstem pools were
formed by channel bends, bedrock, LW pieces, and LW jams (Figure 5; Figure 10). Substrate in this
reach was predominantly gravel and sand, however cobble was also observed (Figure 11; Table 4).
Boulders were infrequently observed in this reach.
One side channel spanning 791 feet and one braided channel spanning 343 feet were surveyed in this
reach (Figure 12; Table 2). Another side channel departed from this reach but was included in the
downstream Powerlines Reach (Figure 2). There were two medium pools and one extra small pool
observed in the side channe formed by a meander and a LW piece, accounting for 59% of the side-
channel habitat area (Figure 4). The two pools in the braided channels were both classified as extra small
and were formed by a LW jam.
This reach contained some side channel habitat with braids, however the reach lacked main channel
braid habitats, instream cover, and stable wood. The reach was disconnected from floodplain and off-
channel habitat on the left bank due to the presence of the Lazy C development. The left bank was diked
and modified and therefore did not provide adequate riparian cover or slow water area. The
enhancement of this bank presents a restoration opportunity to create slow water edge habitats and add
riparian and bank cover for rearing fall Chinook and coho. Sand was present throughout this reach
which indicates slower velocities than the Lazy C – Upstream Reach. However, the Lazy C development
likely impacts flood conveyance and increases scour and damage to summer chum and other species
redds during high flows (Correa 2003). Stable wood formations were present on the right bank where
slow water rearing habitat was present, but only one mainstem pool was formed by a stable LW jam.
Additionally, many wood pieces in the braid and side channel were small and did not appear
stable.There appears to be adequate spawning habitat in this reach, but restoration focused on improving
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floodplain connectivity and instream enhancement through large wood placement would benefit both
rearing and spawning for summer chum, fall Chinook, and coho (Ames et al. 2000; Correa 2003).
Figure 9. Overview of The Lazy C - Downstream Reach with results from CFS habitat surveys. All wetted braid and side channels were surveyed in this reach. Adult coho and chum were present in this reach, and one spawning location was documented.
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Figure 10. Facing downstream, an example of a pool forming log jam adjacent to the Lazy C development at the downstream end of the Lazy C – Downstream Reach. The Lazy C development confines lateral channel movement on the left bank and the lack of riparian vegetation and eroding banks do not provide adequate cover or slow water habitats and present a restoration opportunity in this reach.
Figure 11. Substrate composition from visual estimates for the Lazy C – Downstream Reach by unit and channel type.
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Figure 12. Facing downstream, the surveyed side channel departs on river right. The side channel provides rearing habitat for juvenile salmonids but lacks stable wood.
Powerlines
The Powerlines Reach was the least confined and largest reach surveyed (Figure 13). The majority of
both the left and right bank are unconfined and covered by native vegetation. Braid and side channel
habitats were frequent throughout this reach, but due to time constraints, only one side channel,
spanning 1,309 feet was surveyed (Figure 14). Riffles and pools were the predominant habitats, and
made up 44 and 42 percent of the wetted main channel area, respectively (Figure 3; Table 2). Nine pools
were observed in this reach, including five large and four medium sized pools, and the pool frequency
(pools per mile) was highest in this reach. Pool spacing was slightly higher than the Lazy C –
Downstream Reach, at 9.1 channel widths per pool (Figure 4; Table 3). Meanders, including channel
bends and confluences, were the most frequent pool forming feature in main channel pools (Figure 5).
Gravel, cobble, and sand comprised the majority of substrate in this reach, however bedrock was
documented in pool units (Figure 15; Table 4).
In the surveyed side channel, pool habitat accounted for the highest proportion of wetted channel area,
followed by riffle, then glide habitat (Figure 3; Table 2). Large wood was abundant in the side channel,
and large wood was cited as the pool forming feature for four of the five pool units (Figure 16). The
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average residual pool depth was 2.3 feet, and four of the pools were classified as medium size (Figure 4;
Table 3). One small pool was also observed. Substrate in the side channel was similar to the main
channel, however fines were also observed in small proportions (Figure 15; Table 4).
Numerous adult salmon, including chum and coho, were observed utilizing pool habitats and spawning
in this reach and juvenile salmonids were observed using large wood throughout the side channel. The
Powerlines Reach contains the highest quality habitat of the reaches surveyed. Pools were frequent and
deep and made up over 40% of the reach habitat area providing habitat for juvenile rearing and adult
holding for chum, fall Chinook, and coho. Little human disturbance was visible in the reach and
confined and modified banks were essentially absent, except for the powerlines at the downstream end
of the reach. Additionally, off-channel habitat was abundant and numerous braids and side channels
were present for fall Chinook, coho, and summer chum spawning and rearing (Correa 2003). Sand was
present throughout this reach which indicates slow velocities and likely indicates this reach is more
resilient to winter floods and redds in this reach would be less at risk of scour (Ames et al. 2000). Large
wood jams were more frequent in this reach in the channel and along banks than other reaches, which
created pools and slow water edge habitats for rearing coho and fall Chinook.
Dosewallips Habitat Assessment
Cramer Fish Sciences 18
Figure 13. Overview of the Powerlines Reach with the results from the CFS habitat surveys. Braids and side channels were surveyed as time allowed and were not a full census. Mainstem diversion locations of unsurveyed
wetted braids and side channels were identified during surveys and general channel locations were mapped using the aerial imagery in GIS.
Dosewallips Habitat Assessment
Cramer Fish Sciences 19
Figure 14. Facing upstream, an unsurveyed braid on river right and surveyed channel on river left in the Powerlines Reach. This highlights the sinuous and unconfined braids of the Powerlines Reach.
Figure 15. Substrate composition from visual estimates for the Powerlines Reach by unit and channel type. Braid and side-channel habitats were surveyed as time allowed and were not a full census of habitats.
Dosewallips Habitat Assessment
Cramer Fish Sciences 20
Figure 16. Facing downstream, an example of functional log jams in the surveyed side channel in the Powerlines Reach.
Dosewallips Habitat Assessment
Cramer Fish Sciences 21
References
Ames, J., G. Graves, and C. Weller. 2000. Summer chum salmon conservation initiative. Report to the
Washington Department of Fish and Wildlife and Point-No-Point Treaty Tribes.
Beechie, T. J., M. Liermann, E. M. Beamer, and R. Henderson. 2005. A classification of habitat types in
a large river and their use by juvenile salmonids. Transactions of the American Fisheries Society
134: 717–729.
Bisson, P. A., J. L. Nielsen, R. A. Palmason, and L. E. Grove. 1982. A system of naming habitat types in
small streams, with examples of habitat utilization by salmonids during low stream flow. Pages
62-73 in N. B. Armantrout, editor. Acquisition and salmonid. Environmental Biology of Fishes
8:203-216.
Correa, G. 2003. Salmon and steelhead habitat limiting factors. Water Resource Inventory Area 16
Dosewallips-Skokomish Basin. Final Report to the Washington State Conservation Commission.
CHaMP (Columbia Habitat Monitoring Program). 2016. Scientific protocol for salmonid habitat surveys
within the Columbia Habitat Monitoring Program. Prepared by CHaMP for the Bonneville
Power Administration.
Frissell, C. A., S. B. Adams, and N. H. Hitt. 2000. Identifying priority areas for salmon conservation in Puget
Sound basin. Flathead Lake Biological Station Open File Report, The University of Montana, Polson,
MT. 155 p.
Leopold, L. B. and M. G. Wolman. 1957. River channel patterns: braided, meandering and straight. U.S.
Geological Survey Professional Papers 262B:39-85, Washington, D.C.
Montgomery, D. R., J. M. Buffington, R. D. Smith, K. M. Schmidt, and G. Pess. 1995. Pool spacing in
forest channels. Water Resources Research 31(4): 1097-1105.
Pleus, A. E., D. Schuett-Hames, and L. Bullchild. 1999. Method manual for the habitat unit survey. TFW
Monitoring Program. TFW-AM9-99-003.
Quinn, T. P. 2018. The behavior and ecology of Pacific salmon and trout. University of Washington
Press, Seattle.
WDFW (Washington Department of Fish and Wildlife) and NWIFC (Northwest Indian Fisheries
Commission). 2014. Statewide Washington Integrated Fish Distribution (SWIFD) Schema and
data dictionary. Pages 5 in a. t. N. I. F. C. Washington Department of Fish and Wildlife, editor.
Olympia, Washington.
Dosewallips Habitat Assessment
Cramer Fish Sciences 22
APPENDIX A: HABITAT SUREY DATA COLLECTION
Table 5: Data collected at the habitat unit level for habitat surveys for mainstem habitats.
Units Description Dropdowns Units
fk_Survey Unique Survey Number - -
pk_Units Unique Unit Number - -
DateCreated Date Surveyed - DD/MM/YYYY
DateModified Date Modified - DD/MM/YYYY
GPS_Top_Lat GPS coordinate taken from the Bad Elf GNSS Surveyor - DD
GPS_Top_Long GPS coordinate taken from the Bad Elf GNSS Surveyor - DD
GPS_Top_EPE GPS coordinate taken from the Bad Elf GNSS Surveyor - -
GPS_Bottom_Lat GPS coordinate taken from the Bad Elf GNSS Surveyor - DD
GPS_Bottom_Long GPS coordinate taken from the Bad
Elf GNSS Surveyor
- DD
GPS_Bottom_EPE GPS accuracy taken from Bad Elf GNSS Surveyor - -
ChannelType MS Channel type Main channel, braid, side channel -
UnitNumber Non-unique sequential unit number for survey - -
UnitType_Dominant Unit type as defined by Bouwes et al. 2011, Units must be at least one wetted width in length and occupy 50% of the wetted width.
Pool, riffle, glide, ponded area, backwater -
PoolType Pool type as defined by hydrology (Bisson et al. 1982) Plunge pool, scour pool, trench pool, dammed pool, backwater pool
-
PoolFormingFeature Feature causing scour and pool formation LWD Piece, LWD jam, boulder, bedrock, beaver dam, confluence, channel bend
-
UnitType_SubDominant A subdominant unit must be at least one wetted width in length Pool, riffle, glide, ponded area, end point, backwater -
SubDomUnitPercent Percentage of channel occupied by the subdominant unit - %
UnitLength Total wetted length of unit - m
UnitWidth25 Wetted width at 25% of unit length - m
Dosewallips Habitat Assessment
Cramer Fish Sciences 23
Units Description Dropdowns Units
UnitWidth50 Wetted width at 50% of unit length (taken for pond units) - m
UnitWidth75 Wetted width at 75% of unit length - m
UnitDepth25 Depth at 25% of unit length measured for riffles, glides, and ponded areas
- m
UnitDepth50 Depth at 50% of unit length measured for ponded areas and for maximum depth of pool
- m
UnitDepth75 Depth at 75% of unit length measured for riffles, glides, and ponded areas
- m
PoolTailDepth Depth at tail out of pools - m
Subs_Bedrock Percent of unit substrate composed of bedrock - %
Subs_Boulder Percent of unit substrate composed of boulders - %
Subs_Cobble Percent of unit substrate composed of cobble - %
Subs_Gravel Percent of unit substrate composed
of gravel
- %
Subs_Sand Percent of unit substrate composed of sand - %
Subs_Fines Percent of unit substrate composed of fines - %
Well_sorted Substrate well sorted - %
Comments - - -
NoJamsPresent - Y/N - NoLWDPiecesPresent - Y/N -
APPENDIX C
DATA GAPS SUMMARY MEMO
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NATURAL SYSTEMS DESIGN | September 9, 2020
To: Tami Pokorny – Jefferson County Public Health Department
From: Scott Katz, John Soden, Tim Abbe, and Torrey Luiting, Natural Systems Design Inc.
Date: September 9, 2020
Re: Dosewallips Powerlines/Lazy C Resiliency Plan – Background Data Review, Data Gaps, and
Field Plan
INTRODUCTION
The Jefferson County Public Health department has contracted with Natural Systems Design (NSD) to undertake
a project to characterize the geomorphology and salmon habitat, develop a hydraulic model and conceptual
restoration designs, and develop a resiliency plan on the Lazy C and Powerlines reaches of the Dosewallips River
near Brinnon, Washington. The project area is located between river miles (RM) 1.0 and 2.6 and encompasses
the entirety of the Lazy C housing development as well as publicly held aquatic lands.
As part of the initial project development, NSD reviewed publicly available background information and acquired
publicly available geospatial data. Through this, NSD identified data gaps which it used to inform the
development of a field plan to guide field work in late September 2020. This memo outlines the findings from
the initial background data review, data gaps identification, and field plan development activities.
BACKGROUND DOCUMENT REVIEW
NSD reviewed several reports that focused on the habitat, geomorphic, and flooding conditions of the project
area. The following section presents a summary of the relevant findings of each report.
Salmon and Steelhead Habitat Limiting Factors – WRIA 16 – Dosewallips-
Skokomish Basin – Correa, 2003
This study reports a detailed assessment of habitat limiting factors within the Dosewallips River. The analysis
groups the project area within a larger analysis reach that extends downstream to the river mouth. Therefore,
all findings may not be applicable to the Lazy C and Powerlines reaches included in this study.
The study represents a broad assessment of conditions within the project area. However, this data was further
refined in later studies (such as Labbe et al., 2005). The limiting factors information will be used to evaluate
general watershed conditions.
The habitat condition ratings stated by the Correa 2003 report are presented in Table 1.
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Table 1. Limiting factors and habitat condition ratings for the project presented in the WRIA 16 Salmon and
Steelhead Habitat Limiting Factors Analysis (Correa, 2003). Note that the project area was included in a larger
analysis area that extended downstream to the mouth of the Dosewallips River.
Limiting Factor Habitat Condition
Rating
Notes
Fish Access Good
Floodplain Connectivity Poor The report states that floodplain connectivity is “intact” within the Powerlines reach,
but that dikes along the left bank of the Lazy C reach prevent floodplain connectivity
Floodplain Habitat Good
Large Wood Poor These findings were further refined in the Labbe et al., 2005 study described below
Fine Sediment Data Gap
% Pools Data Gap This data was presented in the Labbe et al., 2005 study described below
Pool Frequency Data Gap /
Good This data was presented in the Labbe et al., 2005 study described below
Pool Quality Poor This data was presented in the Labbe et al., 2005 study described below
Bank Stability Poor
Sediment Supply Poor
Mass Wasting Good
Road Density Good
Riparian Condition Poor
Water Temperature Fair
Dissolved Oxygen Data Gap
Hydrologic Maturity Data Gap
% Impervious Good
Nutrients Poor
Channel Migration Zone Study, Jefferson County, Washington – Duckabush,
Dosewallips, Big Quilcene, and Little Quilcene Rivers - Klawon, 2004
This study delineated a channel migration zone (CMZ) within the study area using historical aerial imagery and
field work to document characteristics of the alluvium within the study reach (Figure 1). The project area was
assessed as two separate reaches (Lazy C and Powerlines). In the Powerlines Reach (Reach D of the study) the
erosion hazard area was defined by seven channel migration measurements from 1970-2002 which yielded an
erosion hazard area (EHA) with a width of approximately 400 ft. The authors state that the meander sequence
within the Powerlines Reach appears to have a growth/cut-off cycle of approximately 20 years based on their
analysis. In the Lazy C Reach (Reach E of the study). the channel was relatively stable during their analysis period
and did not “migrate more than one channel width along the entire reach”. Because of this, the EHA was
defined by an average channel width of 67 feet. At the boundary of the reaches, the EHA transitions to a width
of 230 feet which is the average width of reaches D and E.
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Figure 1. Channel Migration Zone Delineation for the project area as presented in Klawon, 2004 and
modified slightly to indicate current project area.
The author’s state that the river appears to be incised through the Lazy C Reach - a finding that is based on
geomorphic evidence in early photographs and LiDAR that shows numerous channels have existed on the
surface (now Lazy C development) in the past. They state that because of the historical incision, they excluded
the upstream portion of the Lazy C development from the Avulsion Hazard Zone (AHZ) and only included the
lowest portion due to recent aggradation. They also state that “further work could determine the rate of
sedimentation to assess whether aggradation could progress at a rate upstream to a level that might cause an
avulsion hazard.” The report also states that recent large flows have inundated the margins of the Lazy C
surface, particularly at the upstream end.
A re-evaluation of the CMZ through the project area using updated aerial imagery and field data will be
conducted as part of this project. The CMZ analysis will also focus on the current avulsion hazard risk through
the Lazy C and assess the status of channel aggradation as noted by Klawon, 2004.
Dosewallips River Habitat Assessment – Labbe et al., 2005
The study was conducted to collect, analyze, and report aquatic habitat data within the Dosewallips River to
guide aquatic habitat protection and restoration efforts in the watershed. The study relied heavily on geospatial
data which was supplemented by field surveys. The entire project area was included in the study as two
separate reaches – Lazy C and Powerlines.
The study describes historical human activities that occurred within the project area and have contributed to the
degradation of aquatic habitat. The study states that the project area was highly impacted by splash dam
operations that occurred at the upstream end of the canyon and that the incision noted by Klawon, 2004 may be
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due in part to historical splash dam operations between 1917-1926. In discussing changes to aquatic landforms
and hydrologic patterns within the Lazy C, the report notes that “early settler accounts [of the project area]
mention a ‘slough backwater’ from the river fed by a creek descending the north valley sidewall by the Lazy C
development entry road.” Even though the slough no longer exists, the authors noted that there is evidence in
the 1939 aerial imagery and 1958 water right application that confirm the sloughs location. They also speculate
that the ground was re-graded and the creek ditched against the north valley wall during development of the
Lazy C. Resident interviews also corroborated the information about the slough, describing “lake-like” conditions
during the wintertime at Lazy C. Residents also mentioned floodplain filling, active channelization, and wood
removal. The report also states that a left bank road at the downstream end of the Lazy C development had
been built by 1973 and at least 6 homes were present. Most of the road was washed out by 1982 and by 1994
the homes had been abandoned. These parcels can still be seen on the Jefferson County parcel map and are
now within the river corridor (Figure 2).
Figure 2. Mapped parcels that are currently in the river corridor at the downstream end of the Lazy C
development. Labbe et al., 2005 noted that these properties were eroded by the river between 1973-1994.
The figure shows 2020 Jefferson County parcel data and the 2017 NAIP aerial image.
The Labbe et. al. study also describes the habitat conditions within the project area, focusing on the presence
and frequency of pools and large wood (Figure 3). It notes that large wood and pools are sparse within the Lazy
C reach and that when present, most pools were formed against scour resistant banks. In contrast, the pool and
large wood frequency within the Powerlines Reach were the highest measured in any mainstem reach of the
study. In the Powerlines Reach, 70% of the pools were formed by large wood. The report also states that the
reach is “fully connected to its floodplain,” however they do not base that finding on hydraulic modeling results.
The Powerlines Reach also contained 503 meters of perennial side channels and over 270 m of fish accessible
JEFFERSON COUNTY PUBLIC HEALTH DEPARTMENT DOSEWALLIPS POWERLINES/LAZY C RESILIENCY PLAN
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tributary habitat during the time of the study. Two of the side channels in the reach – the Powerlines and Lazy C
side channels – appeared to be heavily modified by wood removal, channelization, and riparian forest removal.
The current project will re-evaluate the habitat within the project reaches under current (2020) conditions and
compare the findings with those from the Labbe et al., 2005 study.
Figure 3. Results from the habitat assessment for the project area presented in the Labbe et al., 2005 study
as Figure A 3. Note the lack of wood and pools within the Lazy C reach and the presence of the Lazy C and
Powerlines side channels within the Powerlines Reach.
Duckabush and Dosewallips Comprehensive Flood Hazard Management
Plan – Jefferson County Department of Community Development and
HDR, 2009
The study was conducted to evaluate the existing flood risks within the Duckabush and Dosewallips Rivers and
to identify flood hazard management alternatives to reduce those risks. The study conducted basic hydrologic
analyses based on gage data (from the Duckabush) and assessed the existing land use and infrastructure within
the study area. It also conducted interviews of valley residents and discussed the history of flooding within the
watersheds. The current project area is represented by reaches D and E in the flood study (Figure 4).
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Figure 4. Reach boundaries used for the Duckabush and Dosewallips Comprehensive Flood Management
Plan. The current project reach lies within Reach D and Reach E of the 2009 study.
The study notes that the initial intent for the Lazy C development began in 1933 and that almost the entire
development lies within mapped floodplain (supported by existing FEMA maps) which has caused it to
experience flooding several times in recent history. The study states that the major flooding problems within
the Lazy C are caused by over-bank flooding that originates from a low-lying area at the upstream end of the
development, as well as bank erosion. It describes that some “streambank erosion measures” were installed
along the left bank of the river throughout the length of the development and that the measures have had
mixed effectiveness. These erosion measures include projects conducted in the mid-1990’s by Jefferson County
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Public Works which included placing and anchoring logs and stumps. The study does not describe the flood risks
within the Powerlines Reach.
The current project will re-evaluate the flood risks within the project area using a 2-dimensional hydraulic
model. This will allow for specific flood risks to be quantified and described on maps of the project area – a task
that was not conducted in the 2009 study.
GEOSPATIAL DATA ACQUISTION
As part of this task, NSD acquired the publicly available geospatial data to support the project. The data acquired
to date is presented in Table 2. As part of this task, NSD also compiled the Jefferson County parcel layer to map
existing land ownership and zoning/land use within the project reach (Figures 5 and 6 attached); these data will
help inform potential project opportunities and constraints.
Table 2. Geospatial data of the Dosewallips River project area
DATA TYPE DATE SOURCE NOTES
Topographic Data
2002 bare-earth LiDAR DEM 2002 Puget Sound LiDAR consortium Collected between 1/1/02-3/31/02 (Specific collection date unknown)
2002 highest hit LiDAR DSM 2002 Puget Sound LiDAR consortium Collected between 1/1/02-3/31/02 (Specific collection date unknown)
2018 bare-earth LiDAR DEM 2018 WA DNR LiDAR portal Inquiry into specific data collection date needed
2018 highest hit LiDAR DSM 2018 WA DNR LiDAR portal Inquiry into specific data collection date needed
Aerial Imagery
National Agricultural Imagery Program (NAIP)
2005 NAIP 2005 NRCS data portal
2009 NAIP 2009 NRCS data portal
2011 NAIP 2011 NRCS data portal
2013 NAIP 2013 NRCS data portal
2015 NAIP 2015 NRCS data portal
2017 NAIP 2017 NRCS data portal
2019 NAIP 2019 NRCS data portal
Other Imagery
1939 Aerial Single Pane 8/7/1939 USGS Earth Explorer Georeferencing needed
1939 Aerial Single Pane 10/12/1939 USGS Earth Explorer Georeferencing needed
1951 Aerial Single Pane 9/1/1951 USGS Earth Explorer Georeferencing needed
1968 Aerial Single Pane 9/4/1968 USGS Earth Explorer Georeferencing needed
1972 Aerial Single Pane 7/20/1972 USGS Earth Explorer Georeferencing needed
1979 Aerial Single Pane 7/1/1979 USGS Earth Explorer Georeferencing needed
1980 imagery 7/29/1980 USGS Earth Explorer Georeferencing needed
1991 imagery 7/31/1991 USGS Earth Explorer Georeferencing needed
1994 imagery 6/20/1994 USGS Earth Explorer Georeferencing needed
Geology/Geomorphology
1:24,000 surface geology WA DNR
JEFFERSON COUNTY PUBLIC HEALTH DEPARTMENT DOSEWALLIPS POWERLINES/LAZY C RESILIENCY PLAN
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DATA TYPE DATE SOURCE NOTES
Flood and Erosion Risk Assessments
Channel Migration Zone
mapping
2004 Jefferson County GIS Portal;
Klawon, 2004
FEMA Flood zones Unknown FEMA
Landslide Hazards Jefferson County GIS Portal
Erosion Hazards Jefferson County GIS Portal
Land-use and ownership
Jefferson County Parcel Layer
Jefferson County GIS Portal Land ownership and land use/zoning is presented on attached figures
Fish use
Statewide Washington Integrated Fish Distribution
Washington Geospatial Data Portal
DATA GAPS ANALYSIS
NSD reviewed the background documents and geospatial data to identify potential gaps in the data necessary to
conduct the current project. Table 3 presents the results of the data gap analysis.
Table 3. Identified Data Gaps
DATA GAP NOTES OFFICE
ANALYSIS
FIELD
ANALYSIS PLAN TO FILL DATA GAP
Bathymetric data
A bathymetric survey of the
project area has not been
conducted
N/A N/A
This task is not included under the current scope of work. Bathymetric LiDAR may be collected in the future depending on funding.
Relative
Elevation
Model (REM)
A final REM has not been developed for the project site using the most recent
topographic information
Yes No
The REM developed by NSD for the
project proposal will be updated and
refined using the 2018 LiDAR DEM.
Channel
Migration
Zone (CMZ)
The CMZ presented in Klawon, 2004 does not
include recent channel
migration rates and channel
locations. The avlusion
hazard areas may not have
been adequately analyzed in
Klawon, 2004 as well
Yes Yes
An update to the CMZ will be
conducted using recent aerial imagery
and topography. This will include a
detailed evaluation of the avulsion
hazard risk through the Lazy C.
Landslide
hazards
The Landslide Hazard layer
from the Jefferson County
GIS data portal does not
incorporate field
observations nor recent
LiDAR data to refine the
conclusions reached by the
solely geospatial analysis.
Yes Yes
A qualitative landslide hazard analysis
will be conducted using recent LiDAR
data, recent geologic maps, and field
observations
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DATA GAP NOTES OFFICE
ANALYSIS
FIELD
ANALYSIS PLAN TO FILL DATA GAP
Hydrologic
peak flow data
There has not been a gage
on the Dosewallips river
since 1968. Hydrology
information used in other
projects has been based on
the historical gage as well as
the existing gage on the
Duckabush River
Yes No
Flood recurrence intervals (peak flows)
will be estimated using recent
observations on nearby gages, the
historical gage record, and StreamStats
and be supported by the findings in
background documents
Hydraulic
patterns,
inundation
extents, and
flood risk
A 2-dimensional hydraulic model that estimates the
hydraulic patterns,
inundation extents, and
flood risk of the project
reach has not been
developed
Yes No
A hydraulic model will be developed as part of this project and be based on
updated hydrology and 2018 LiDAR
topography. Estimates of depth,
velocity, and inundation extent will be
mapped and used to develop flood risk
zone delineations.
Aquatic
habitat -
Channel types
Channel types (mainstem,
braid, side-channel) have
not been mapped for
current conditions
Yes Yes Data will be collected as part of this
project
Aquatic
habitat -
Coarse channel
units
Coarse channel units (pools,
riffles, glides) have not been
mapped for current
conditions
Yes Yes Data will be collected as part of this
project
Streambank
condition
Detailed descriptions of
bank material and existing
condition have not been
collected
No Yes Data will be collected as part of this
project
Bank armoring
A spatial dataset of existing
bank armoring (e.g. rip-rap,
dikes, cabled wood, etc.) has
not been created
No Yes Data will be collected as part of this
project
Stable large
wood jams
The most recent large wood
data was presented in Labbe
et al,. 2005
Yes Yes Data will be collected as part of this
project
Dominate substrate class and distribution
Data of the current
substrate size distribution
has not been collected
No Yes Data will be collected as part of this project
FIELD PLAN
NSD and Cramer Fish Sciences will conduct a 1-day field survey of the project reach on September 23, 2020 to fill
the data gaps noted for field collection in Table 3 and to develop a more holistic understanding of the project
reach. The field survey will specifically focus on collecting the data presented in Table 4.
JEFFERSON COUNTY PUBLIC HEALTH DEPARTMENT DOSEWALLIPS POWERLINES/LAZY C RESILIENCY PLAN
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NATURAL SYSTEMS DESIGN | September 9, 2020
Table 4. Field Data Collection Plan
FEATURE CLASS ATTRIBUTES TO BE RECORDED FEATURE TYPE TO
BE COLLECTED
General observations
Location
Feature
Notes
Photograph
Point
Reach description
Location Channel type (pool-riffle, plane bed) Morphology (confinement, presence of point bars, mid-channel bars) General observations Upstream and Downstream photographs (taken of as much of stream as possible)
Point
Infrastructure (culverts,
bridges, any other constraints)
Location
Description
Photograph
Point
Channel types
Location
Description
Channel type (mainstem, braid, side-channel)
Photograph
Polygon
Coarse channel units
Location Description Unit type (e.g. pool, riffle, glide) Formative mechanism (if pool- e.g. wood, bedrock, meander) Width and depth (when feasible)
Polygon
Stable log jams
Location
Description
Longitudinal Depth (ft)
Height (ft)
Width (ft)
% wood of space (volume) jam occupies
Photograph
Polygon
Dominant substrate class
Patch delineation or location of pebble count % size class composition (sand, gravel, cobble, etc.) Surface pebble count ID (if time allows) Photograph
Polygon
Stream bank mapping
Location
Stratigraphy (cobble, gravel, sand layers and elevations
contacts)
Land cover description (Forested, Pasture, Infrastructure, other)
Evidence of recent erosion (Y/n)
Failure mechanism (i.e. slumping, block erosion, etc.)
Photograph
Line
JEFFERSON COUNTY PUBLIC HEALTH DEPARTMENT DOSEWALLIPS POWERLINES/LAZY C RESILIENCY PLAN
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NATURAL SYSTEMS DESIGN | September 9, 2020
FEATURE CLASS ATTRIBUTES TO BE RECORDED FEATURE TYPE TO BE COLLECTED
Bank armoring
Location
Description
Material
Condition
Photograph
Line
High water marks
Location
Description
Approximate height above bank (ft)
Photograph
Point
Potential landslide hazards
Location
Description
Photograph
Polygon
Riparian community
(Qualitative Description)
Location
Description
Dominant tree and shrub species
Invasive species present (species description)
Approximate DBH of largest trees
Photograph
Point
Design notes
Location
Description
Photograph
Design intent
Structure location? (Y/N)
Point
G
G
G
G
G
G
1
2
1,126,615 264,572
264,572Author: NSD Staff Date: 9/9/2020 Path: N:\Projects\Jefferson County\Dosewallips Powerlines Lazy C Resiliency Plan\GIS\maps\mxd\Dosewallips_Land_Ownership.mxd¹Dosewallips Resiliency Plan
Figure 5. Land Ownership
Lambert conformal conic projection, NAD 1983 State Plane Coordinate System (WA North Zone). Land Ownership Data source: Jefferson County Public Parcel DataAerial Imagery: 2017 NAIP
0 250 500Feet
Vicinity Map
¹0 1,250 2,500Feet
Land Ownership
PRIVATE
POPE RESOURCES
AMERICAN TIMBER RESOURCE LLC
TOWN OF BRINNON
JEFFERSON COUNTY
WA DNR
WASHINGTON STATE PARKS
OLYMPIC NAT'L FOREST
G River Mile (USGS)
G
G
G
G
G
G
1
2
1,126,615 264,572
264,572Author: NSD Staff Date: 9/9/2020 Path: N:\Projects\Jefferson County\Dosewallips Powerlines Lazy C Resiliency Plan\GIS\maps\mxd\Dosewallips_Land_Use.mxd¹Dosewallips Resiliency Plan
Figure 6. Land Use / Zoning
Lambert conformal conic projection, NAD 1983 State Plane Coordinate System (WA North Zone). Land Ownership Data source: Jefferson County Public Parcel DataAerial Imagery: 2017 NAIP
0 250 500Feet
Vicinity Map
¹0 1,250 2,500Feet
Land Use / Zoning
RR-20 - Rural Residential
RR-5 - Rural Residential
CF-80 - Commercial Forest
RF-40 - Rural Forest
IF-20 - Inholding Forest
AL-20 - Local Agriculture
PPR - Parks, Preserves, and Recreation
G River Mile (USGS)
APPENDIX D
HYDRAULIC MODEL DEVELOPMENT
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NATURAL SYSTEMS DESIGN | April 28, 2021
DOSEWALLIPS RESILIENCY PLAN: HYDRAULIC MODEL
DEVELOPMENT APPENDIX
HYDRAULIC MODEL DEVELOPMENT
A hydraulic model of the Dosewallips River was developed using Hydronia’s RiverFlow-2D Plus GPU and Aquaveo
SMS v13.0 computer software. RiverFlow-2D is a two-dimensional finite volume computer model that provides
depth averaged hydraulic parameters at centroids within a triangular mesh model domain.
Mesh Development and Roughness Categories
The model domain encompasses 2 river miles, with the upper boundaries just upstream of river mile (RM) 3, and
the lower boundary at RM 1 where the floodplain narrows into a bedrock canyon. The topographic data is from
LiDAR collected in 2017/2018 (Quantum Spatial, 2019).
The model mesh was created with fine mesh spacing in the channel and in floodplain channels, with expanded
mesh spacing in less topographically complex areas further from the stream, using criteria for mesh spacing
shown in Table 1.
Table 1. Mesh Spacing Guidelines for Breakline Categories
LOCATION VERTEX SPACING (FT)
Road 10
Bank 10
Floodplain channels 10
Boundary 15
Hydraulic resistance is characterized in the model by polygons representing differing surface roughness types
such as main channel, pasture, or paved road. The full list of roughness categories and their associated
Manning’s n values is in Table 3. Roughness categories were manually delineated using 2017 aerial imagery.
Table 2. Calibrated Manning's n roughness values for each roughness category.
CATEGORY MANNING'S N VALUE
Active Channel 0.035
Side Channel 0.045
Forested Gravel Bar 0.08
Bare Earth 0.03
Pasture 0.03
Forest 0.08
Road 0.015
Natural Logjam 0.15
Building 0.99
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Hydrology and Model Boundary Conditions
The model was run for a series of three representative flow scenarios – the 1-year, 10-year, and 100-year floods
– to evaluate hydraulic parameters at the project site. To develop estimated inflows for the Dosewallips model,
NSD performed a hydrologic analysis of the region. This analysis focused on two USGS gages: USGS gage
#12053000, Dosewallips River near Brinnon, WA (henceforth referred to as the Dosewallips gage) and USGS
gage #120454000, Duckabush River near Brinnon, WA (henceforth the Duckabush gage) (Figure 1). Accurately
representing the magnitude of peak flows within the project reach is challenging because the Dosewallips gage
only operated from 1930-1951, and so offers only a small and out-of-date period of record from which to
extrapolate. No other gage with a greater period of record was available on the Dosewallips River. To account
for this, the Duckabush gage was identified as a possible surrogate to streamflow conditions on the Dosewallips
River. The Duckabush River watershed is south of and directly adjacent to the Dosewallips River watershed and
has similar characteristics of slope, relief, precipitation, and land use (Table 3).
Figure 1. Map of Dosewallips and Duckabush Basins showing locations of USGS gages.
12053000
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Table 3 Basin characteristics for the Dosewallips and Duckabush Rivers. Data downloaded from Stream
Stats (USGS 2016).
Parameter Dosewallips River
at USGS Gage
Dosewallips River at
Lazy C
Duckabush River at
USGS Gage
Drainage Area (mi2) 93 113 66
Basin average annual
precipitation (in) 96 90 110
Mean basin slope (%) 62% 60% 63%
Canopy Cover (%) 60% 63% 65%
Mean basin elevation (ft) 4140 3740 3530 Maximum basin elevation (ft) 7770 7770 6750 Minimum basin elevation (ft) 306 65 271
Relief (ft) 7460 7700 6480
To estimate discharge values on the mainstem, a peak flow analysis of both the Dosewallips gage and the
Duckabush gage was performed using Log-Pearson schedule 3b methodology. For the Dosewallips gage, the
resulting 10-year and 100-year flows were then scaled to the project site using the USGS drainage-area ratio
method for ungaged sites, which involves a weighted average of the USGS regional regression equation results
with the drainage-area-scaled results of the gage analysis. For the Duckabush gage, since the drainage area ratio
of the ungaged site to the gage was over 1.5, the USGS regional regression equation results and the drainage-
area-scaled results of the gage analysis were given equal weight and the reported 10-year and 100-year results
are a simple average of the two. The 1-year flow was scaled from each gage using a simple drainage area ratio,
as the USGS does not provide coefficients for its regional regression equations for this recurrence interval.
To identify discharge estimates for each recurrence interval, the results of the above analysis of the Duckabush
and Dosewallips were compared. Since the Duckabush gage has a greater and more current period of record,
the 10-year and 100-year floods scaled from the Duckabush gage were used as the estimated discharge values
for the hydraulic model. The 1-year flood used for the hydraulic model is an average of the discharge value
scaled from the Duckabush and the Dosewallips gage, since there was no USGS regional regression equation
available for this recurrence interval and therefore the estimates are less certain. Table 4 shows the scaled
results of the gage analyses as well as the final estimated discharge values for the project site.
The hydraulic model was built using 2019 LiDAR that was collected on on 10/6/17 and 7/22/18 and does not
contain bathymetry data. Average discharge on these days was 50 cfs and 140 cfs on the Duckabush gage
respectively. Since it is unknown which day the project area was captured, 50 cfs was adopted as the LiDAR flow
to be conservative. This flow was determined to be low enough in comparison to the scale of the flood flows
being modeled that it would not affect the results. Therefore since the models are run on top of a water surface
that corresponds to a discharge of 50 cfs, 50 cfs was subtracted from each of the discharge values shown in
Table 4 to arrive at the final model inflow values.
The models were run in a simulated steady state; i.e., the inflow hydrographs look like stair steps, with each
peak flow of interest running long enough for the model to equilibrate before jumping to the next flow of
interest. The model has only one outflow boundary, which was set to uniform flow outflow with a slope of
0.0003 ft/ft.
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Table 4. Estimated Discharge Values
RECURRENCE
INTERVAL
DISCHARGE AT PROJECT
SITE SCALED FROM
DOSEWALLIPS GAGE
(CFS)
DISCHARGE AT
PROJECT SITE SCALED
FROM DUCKABUSH
GAGE (CFS)
FINAL DISCHARGE
ESTIMATE AT
PROJECT SITE
(CFS)
1-year 1,620 2,570 2,100
10-year 9,180 11,420 11,420
100-year 15,900 17,120 17,120
Climate Change Estimates
Once peak flows were determined for the project site, it was necessary to estimate the impact that climate
change would have on these flows in order to understand and model future floods. The Columbia Basin Climate
Change Scenarios (CBCCS) project summarizes climate change projections for many watersheds, the closest to
the Dosewallips being the Skokomish River (Hamlet 2010). For each basin the CBCCS projects the 20-year, 50-
year, and 100-year recurrence interval floods into the future to estimate their magnitude in the years 2070-2099
based on one of two climate change scenarios. For this project the A1B climate change scenario was used, which
is the higher of the two scenarios and the closest to current climate change projections.
Data were downloaded from the Columbia Basin Climate Change Scenarios Project website at
http://warm.atmos.washington.edu/2860/. These materials were produced by the Climate Impacts Group at the
University of Washington in collaboration with the WA State Department of Ecology, Bonneville Power
Administration, Northwest Power and Conservation Council, Oregon Water Resources Department, and the B.C.
Ministry of the Environment. The percent change in the Skokomish River floods from 2020 to 2070-2099 as
estimated by the CBCCS was determined and then applied as a multiplier to the Dosewallips floods to estimate
climate change flows (Table 5). Note that the lowest flood for which the CBCCS makes estimates is the 20-year
flood; therefore, the multiplier applied to the Dosewallips 1-year and 10-year floods is the CBCCS-estimated 20-
year flood percent increase. These are likely conservative estimates as the relative impact of climate change
would be expected to decrease with the frequency of the flood.
Table 5. The magnitude of future peak flows projected with climate change impacts for 2070-2099.
RECURRENCE
INTERVAL
PRESENT DISCHARGE
ESTIMATE AT LAZY C
(CFS)
PERCENT INCREASE DUE
TO CLIMATE CHANGE
FUTURE (2070-2099)
DISCHARGE
ESTIMATE AT LAZY C
(CFS)
1-year 2,100 18% 2,480
10-year 11,420 18% 13,480
100-year 17,120 23% 21,060
Validation
To ensure that the model accurately reflects real world conditions, data provided by the community regarding
locations, depths, and timings of flooding was compared to model results.
The first point of comparison was provided by a picture taken of flooding on the intersection of Appaloosa Dr
and Mustang Lane on December 11, 2014 at 10:40 am, and a picture of the same location the following day after
the flood had receded (Figure 2). By comparing the stop sign in the two pictures, it is possible to estimate that
the depth of water during flooding in the location was approximately 2 ft. Flow at the Duckabush gage at this
date and time was around 2,500 cfs, which tells us that flow at the project site was approximately 4,200 cfs
when the flow is scaled by drainage area. The magnitude of this flow falls in between the modeled 1-year and
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10-year recurrence intervals floods; however, the model has a brief ramp-up period in which discharge increases
from the 1-year magnitude to the 10-year magnitude during which results at intermediate flows can be seen. At
the 1-year flood, when discharge is 2,100 cfs, this intersection is not inundated, and at the 10-year flood when
discharge is 11,420 cfs, this intersection is under 0.5-2.5 ft of water. Intermediate results are less reliable as the
model is not given time to equilibrate at intermediate flows, but the model shows that this intersection begins
to partially inundate when mainstem flow is approximately 4,300 cfs, at which point the depth is up to 1.8 ft,
and is fully inundated when mainstem flow reaches approximately 6,700 cfs.
Given the uncertainties surrounding flow estimates on the day of the photo (since the estimate must be based
on a different basin, see Hydrology section), as well as the approximate nature of the depth estimate from the
photo, an exact match from the model should not be expected. This photo therefore validates the model – both
show inundation of approximately 2 ft at this intersection when flow is between 4,000 cfs and 4,500 cfs. The
model does not show full inundation of the intersection until 6,700 cfs , while the photo shows full inundation at
what was estimated to be 4,200 cfs, but as mentioned above the intermediate results between the 1-year and
10-year floods are not given time to equilibrate in the model so this discrepancy may simply be a result of the
model being focused on different flood sizes.
Figure 2. Picture of 2014 flooding at the intersection of Appaloosa Dr and Mustang Ln (left) compared to a
picture of the same intersection the following day (right).
The second point of comparison is a parcel map marked up by landowners to illustrate the flow path that floods
typically take through the Lacy C development based on their experience (Figure 3). This is not associated with
any particular discharge or depth but can be compared to the flowpath that the model shows floodwaters
following when they first enter the Lazy C development. Figure 4 shows the model results in the same area at
approximately 5,400 cfs, as floodwaters are just entering the Lazy C development. The flowpath in Figure 4
mirrors that drawn by landowners in Figure 3 – the crossing of Appaloosa Dr is at the same place, and
floodwaters come up through parcels 29 and 30 in the model as drawn. Between Appaloosa Drive and Mustang
Lane there is some deviation due to the complexity of topography, but the general pattern of flow from parcel
159 to the intersection of Appaloosa Dr and Mustang Lane is the same.
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Figure 3. Parcel map marked up by landowners in red to illustrate typically flood flow path.
Figure 4. Hydraulic model results at approximately 5,400 cfs overlaid on the parcel map, showing the flow
path of floodwaters as they enter the Lazy C development.
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REFERENCES
Hamlet, A.F., P. Carrasco, J. Deems, M.M. Elsner, T. Kamstra, C. Lee, S-Y Lee, G. Mauger, E. P. Salathe, I. Tohver,
L. Whitely Binder, 2010, Final Project Report for the Columbia Basin Climate Change Scenarios Project,
http://warm.atmos.washington.edu/2860/report/.
Mastin, M.C., Konrad, C.P., Veilleux, A.G., and Tecca, A.E., 2016, Magnitude, frequency, and trends of floods at
gaged and ungaged sites in Washington, based on data through water year 2014 (ver 1.2, November
2017): U.S. Geological Survey Scientific Investigations Report 2016–5118, 70 p.,
http://dx.doi.org/10.3133/sir20165118.
Quantum Spatial, 2019. Olympic Peninsula, Washington 3DEP Lidar – Area 1 Technical Data Report. Project
conducted on behalf of the U.S. Geological Survey.
U.S. Geological Survey, 2016, The StreamStats program, online at http://streamstats.usgs.gov, accessed on
2/14/2021.
APPENDIX E
SUMMARY OF IMPAIRMENTS
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NATURAL SYSTEMS DESIGN | April 28, 2021
RESILIENCY PLAN – SUMMARY OF IMPAIRMENTS
Lazy C Upstream Reach
PROCESS IMPAIRMENTS POTENTIAL DESIGN ACTIONS
Channel and Floodplain
formation
(sedimentation,
erosion)
River confined to straight entrenched channel along southside of
valley with no right bank floodplain; little left bank floodplain
engagement.
Floodplain development limits potential for channel & floodplain
formation.
Increase large wood loading to encourage complex channel and
floodplain formation.
Excavate floodplain benches along left bank to spread out flow and
reduce in-channel velocities.
Acquire floodplain properties on left bank to provide space necessary to
restore natural processes.
Floodplain connectivity Incised and confined channel limits floodplain connectivity.
Localized bank protection along left bank is inhibiting formation of
an inset floodplain.
Floodplain development limits potential for improving floodplain
connectivity.
Increase large wood loading to encourage channel and floodplain
engagement.
Excavate floodplain benches along left bank to spread out flow and
reduce in-channel velocities.
Acquire floodplain properties on left bank to provide space necessary to
restore natural processes.
Sediment transport /
bed mobility
Channel confinement increases sediment transport capacity and
limits gravel retention and bar formation.
Increase large wood loading to partition shear stress and aggrade
sediment.
Acquire floodplain properties on left bank to provide space necessary to
restore natural processes.
Channel migration Channel confinement limits sediment deposition which reduces
channel migration rates.
Ongoing and historical clearing of in-stream wood limits channel
migration.
Localized bank protection limits channel migration.
Increase large wood loading to encourage channel migration.
Increase large wood loading within floodplain and on edges of
floodplain benches to allow for channel migration while floodplain is
occupied by existing development.
Acquire floodplain properties on left bank to provide space necessary to restore natural processes.
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PROCESS IMPAIRMENTS POTENTIAL DESIGN ACTIONS
Large wood Lack of channel migration limits wood recruitment.
Ongoing and historical clearing of in-stream wood reduce quantity of
instream large wood.
Increase large wood loading.
Acquire floodplain properties on left bank to provide space necessary to
restore natural processes.
Restore conifers to riparian zone to provide future sources of large
wood.
Riparian and Wetland
Habitat Formation
Lack of overbank flooding limits formation of floodplain wetlands.
Deciduous trees dominate riparian zone due to historic forest
clearing.
Increase large wood loading for floodplain connectivity and wetland
habitat formation.
Excavate floodplain benches to increase quantity of floodplain and
wetland habitat.
Acquire floodplain properties on left bank to provide space necessary to
restore natural processes.
Restore conifers to riparian zone to provide future sources of large
wood.
Aquatic Habitat
Formation
Formation of complex aquatic habitat limited by lack of large wood,
channel confinement, and low degree of floodplain connectivity.
Increase large wood loading to increase channel migration, sediment
retention, and aquatic habitat formation (e.g., pools and cover).
Excavate floodplain benches to increase quantity of off-channel habitat.
Acquire floodplain properties on left bank to provide space necessary to
restore natural processes.
Restore conifers to riparian zone to provide future sources of large
wood.
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Lazy C Downstream
PROCESS IMPAIRMENTS POTENTIAL DESIGN ACTIONS
Channel and Floodplain
formation
(sedimentation, erosion)
Floodplain development limits potential for channel & floodplain
formation.
Increase large wood loading to encourage complex channel and
floodplain formation.
Acquire floodplain properties on left bank to provide space
necessary to restore natural processes.
Floodplain connectivity Localized left bank protection is inhibiting formation of an inset
floodplain.
Floodplain development limits potential for improving floodplain
connectivity.
Acquire floodplain properties on left bank to provide space
necessary to restore natural processes.
Sediment transport / bed
mobility
Development is inhibiting natural recovery of gravel retention, bar
formation, and bank erosion.
Acquire floodplain properties on left bank to provide space
necessary to restore natural processes.
Channel migration Localized bank protection and floodplain development limit up-valley
channel migration.
Channel migration rates are increased above historical levels due to
aggradation in Powerlines reach and clearing of riparian vegetation.
Strategically place large wood to slow channel migration rates closer
to historical levels, to buy time for property acquisition and
relocation, and to allow restoration of riparian forest.
Acquire floodplain properties on left bank to provide space
necessary to restore natural processes.
Large wood Clearing of left bank riparian forest limits wood recruitment.
Reduction in channel migration rates due to floodplain development
and bank armoring limits wood recruitment.
Increase large wood loading.
Acquire floodplain properties on left bank to provide space
necessary to restore natural processes.
Restore conifers to riparian zone to provide future sources of large
wood.
Riparian and Wetland Habitat Formation Development and lack of overbank flooding limits formation of floodplain wetlands.
Deciduous trees and immature riparian vegetation due to historical
forest clearing.
Restore conifers to riparian zone to provide future sources of large wood.
Acquire floodplain properties on left bank to provide space
necessary to restore natural processes.
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PROCESS IMPAIRMENTS POTENTIAL DESIGN ACTIONS
Aquatic Habitat
Formation
Formation of complex aquatic habitat limited by lack of large wood,
channel confinement, and low degree of floodplain connectivity.
Increase large wood loading to encourage formation of complex
aquatic habitat, create pools, and provide cover.
Acquire floodplain properties on left bank to provide space
necessary to restore natural processes.
Restore conifers to riparian zone to provide future sources of large
wood.
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Powerlines
PROCESS IMPAIRMENTS POTENTIAL DESIGN ACTIONS
Channel and Floodplain
formation
(sedimentation, erosion)
Upstream channel confinement (e.g., Lazy C, Wolcotts Flats etc.)
increased sediment supply to this sub-reach.
Aggradation coupled with historical forest clearing has transformed
sub-reach from anabranching forested island morphology to a braided wide channel.
Increase large wood loading to encourage forested island
development and stable channel formation as well as narrow
widened channel segments.
Acquire floodplain properties to provide space necessary to restore natural processes.
Floodplain connectivity None Acquire floodplain properties to provide space necessary to restore
natural processes.
Sediment transport / bed
mobility
Frequent bed mobilization and sediment deposition in braided
sections negatively impacts salmon redds.
Increase large wood loading to partition shear stress and reduce bed
mobilization frequency within braided channel sections.
Acquire floodplain properties to provide space necessary to restore
natural processes.
Channel migration Historical forest clearing and low levels of stable large wood increased
channel migration rates above likely historical levels.
High channel migration rates increase risk of avulsion through side
channels which would decrease the amount of in-channel and side-
channel habitat.
Increase large wood loading within main-channel and side-channels
to reduce channel migration rates and avulsion risk and promote
development of forested islands.
Acquire floodplain properties to provide space necessary to restore
natural processes.
Large wood Historical forest clearing and instream wood removal have reduced
levels of stable large wood in the main channel and side channels.
Increase large wood loading throughout the reach.
Acquire floodplain properties on left bank to provide space
necessary to restore natural processes.
Restore conifers to riparian zone to provide future sources of large
wood.
Riparian and Wetland Habitat Formation Channel migration rates greater than historical levels are limiting ability of riparian vegetation to mature. Increase large wood loading to slow channel migration rates closer to historical levels.
Restore conifers to riparian zone to provide future sources of large
wood.
Acquire floodplain properties to provide space necessary to restore
natural processes.
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PROCESS IMPAIRMENTS POTENTIAL DESIGN ACTIONS
Aquatic Habitat
Formation
Increased sedimentation due to upstream channel confinement is
encouraging the formation of unstable morphologies (braided
channels) which negatively impact salmonid habitat.
Increase large wood loading to increase stability of braided channel
habitats, encourage formation of complex habitats, and increase
quantity of pools with cover.
Acquire floodplain properties to provide space necessary to restore
natural processes.
Restore conifers to riparian zone to provide future sources of large
wood.
APPENDIX F
CONCEPTUAL CONSTRUCTION COST ESTIMATES
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Construction Cost Estimate - Lazy C Reach
Natural Systems Design
Analyst:J. Smith
Latest Revision:6/7/2021
Project: Dosewallips Resiliency Plan
Client: Jefferson County Public Health Project No: JEFFCO-005 Allowance for Indeterminates Included in Bid Items:50%
Inflation to 2023 included in Item Cost:6%
Construction
ITEM #ITEM DESCRIPTION WSDOT REF QTY UNIT UNIT COST ITEM COST
1 MOBILIZATION 1 LS 219,901.34$ 219,901.34$ 2 EROSION/ WATER POLLUTION CONTROL MEASURES 1 LS 27,370.00$ 27,370.00$ 3 SITE ISOLATION 1 LS 117,300.00$ 117,300.00$ 4 ACCESS & STAGING 1 LS 39,100.00$ 39,100.00$ 5 APEX JAM 3 EA 46,920.00$ 140,760.00$ 6 LARGE DEFLECTOR 3 EA 70,380.00$ 211,140.00$ 7 SMALL DEFLECTOR 11 EA 46,920.00$ 516,120.00$ 8 LOW PROFILE JAM 8 EA 23,460.00$ 187,680.00$ 9 HABIAT JAMS 1 LS 23,460.00$ 23,460.00$ 10 RIPARIAN RESTORATION 1 AC 3,128.00$ 3,753.60$
Subtotal 1,486,585$ Taxes (as % of Construction Sub-Total)9.1%135,279$
Total (Construction)1,621,864$
Construction Cost Estimate - Powerlines Reach
Natural Systems Design
Analyst:J. Smith
Latest Revision:6/7/2021
Project: Dosewallips Resiliency Plan
Client: Jefferson County Public Health
Project No: JEFFCO-005 Allowance for Indeterminates Included in Bid Items:50%
Inflation to 2023 included in Item Cost:6%
Construction
ITEM #ITEM DESCRIPTION WSDOT REF QTY UNIT UNIT COST ITEM COST
1 MOBILIZATION 1 LS 540,834.03$ 540,834.03$
2 EROSION/ WATER POLLUTION CONTROL MEASURES 1 LS 31,905.60$ 31,905.60$
3 SITE ISOLATION 1 LS 239,292.00$ 239,292.00$
4 ACCESS & STAGING 1 LS 119,646.00$ 119,646.00$
5 LARGE APEX JAM 8 EA 70,380.00$ 563,040.00$
6 APEX JAM 17 EA 46,920.00$ 797,640.00$
7 LARGE DEFLECTOR 2 EA 70,380.00$ 140,760.00$
8 LOW PROFILE JAM 24 EA 23,460.00$ 563,040.00$
9 HABIAT JAMS 1 LS 62,560.00$ 62,560.00$
10 FLOODPLAIN ROUGHNESS JAMS 33 EA 15,640.00$ 516,120.00$
11 RIPARIAN RESTORATION 26 AC 3,128.00$ 81,328.00$
Subtotal 3,656,166$
Taxes (as % of Construction Sub-Total)9.1%332,711$
Total (Construction)3,988,877$