HomeMy WebLinkAboutWDNR-report-shuffleton-flume-monitoring-final report Jan 2018.pdf
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Summary
To determine if a Washington State Department of Natural Resources restoration project
in south Lake Washington improved juvenile Chinook salmon (Oncorhynchus tshawytscha)
habitat conditions, we monitored fish abundance three years before the project (2011-2013) and
three years after the project (2015-2017). The restoration project involved removing 168 m of an
old metal flume structure and replacing it with open gravel/sand beaches and three engineered
logjams (ELJs). Twice a month from January to June we conducted nighttime snorkeling
transects in shallow water to estimate the abundance of Chinook salmon and other fishes. A
BACI (before-after-control-impact) study design was used to assess changes in fish abundance.
The restoration project appeared to have a strong positive effect on juvenile Chinook salmon
abundance. There were roughly nine times as many Chinook salmon observed along the flume
transect (open gravel/sand beach post-project) after the restoration project than before the
project, while there was little difference in the control sites pre- and post-project. In addition,
Chinook salmon were commonly abundant at the ELJs and their densities from January to April
were substantially higher than a small natural logjam and along the open gravel/sand shorelines.
Warmwater fishes (nonnative centrarchids and percids) were also common at the ELJs but they
were only abundant in May and June, when Chinook salmon numbers at these sites were low. In
conclusion, removal of the flume structure and replacing it with a more natural shoreline
appeared to have improved juvenile Chinook salmon habitat conditions in south Lake
Washington. The restored nearshore area now has a large area of preferred habitat for juvenile
Chinook salmon (shallow water < 1 m deep, primarily sand and gravel substrate, a gentle slope,
and some nearby logjams for refuge).
Introduction
A key component of habitat restoration projects is biological monitoring to establish the
effectiveness of the project to target species. Puget Sound Chinook salmon (Oncorhynchus
tshawytscha) are currently listed as threatened under the Endangered Species Act and many
restoration projects have been designed to improve their habitat conditions in lotic and lentic
environments. The Washington Department of Natural Resources (WDNR) completed a large
restoration project in the south end of Lake Washington to benefit Chinook salmon. Both pre-
and post-project monitoring of this project were needed to determine if shoreline conditions have
been improved for juvenile Chinook salmon. This report presents data from six years of
monitoring (three years of pre-project monitoring and three years of post-project monitoring).
Puget Sound Chinook salmon are primarily “ocean-type” which typically emigrate to the
marine environment as subyearlings. During their three to five month juvenile freshwater phase
they can inhabit a wide range of habitat types including large rivers, small streams, lakes, and
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estuaries (Healey 1991). Ocean-type Chinook salmon commonly have two groups of emigrants;
a group that moves downstream as fry and rears in estuaries, coastal ocean habitats, or lakes and
another group that rears in the natal river system and emigrates as parr or smolts (Healey 1991).
In the Lake Washington system, the major Chinook salmon spawning tributary is the
Cedar River and large numbers of fry emigrate from January to April to rear in the south end of
Lake Washington. These fish prefer shallow, non-armored (no bulkheads or rip rap) shorelines
with sand and gravel substrates that have both open beaches and areas with riparian vegetation
that provide woody debris and overhanging vegetation (Tabor et al. 2011a). However, the Lake
Washington shoreline has been extensively developed and resource managers have looked for
opportunities to improve shoreline habitat conditions. The abundance of juvenile Chinook
salmon is substantially higher at sites close to the mouth of the Cedar River (Tabor et al. 2006).
Therefore, restoration projects close to the Cedar River are likely to have a stronger effect on the
Chinook salmon population than projects located further away.
One good location for a restoration project was the Shuffleton Power Plant flume
structure because it had poor habitat conditions, was relatively large, and was only about a half
of a kilometer from the mouth of the Cedar River. The flume was built to help cool water from
the adjacent power plant that began operation in 1929. The power plant has been torn down and
replaced with apartments and a hotel and thus the flume structure was no longer used. This
restoration site is relatively large in comparison to other potential restoration sites in Lake
Washington. The flume structure was part of a 360-m long shoreline section owned by WDNR.
The flume structure consisted of two parallel, vertical steel walls that resulted in poor habitat
conditions (i.e., little shallow water, no sand or gravel substrates, and little structural complexity)
for juvenile Chinook salmon. Also, the steep walls were likely habitat for predators of juvenile
Chinook salmon such as smallmouth bass (Micropterus dolomieu). The area between the two
walls was usually extremely turbid and likely had poor water quality for juvenile Chinook
salmon. In the summer of 2014, a 168-m long section of the flume structure was removed and
replaced with a gentle-sloping gravel/sand beach (see cover photos) and engineered logjams
(ELJs).
The overall objective of this study was to monitor the abundance of juvenile Chinook
salmon and other fishes at the Shuffleton Power Plant flume structure site before and after the
restoration project, which was completed during the summer of 2014.
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Methods
Standard Snorkel Transects
Night snorkeling was used to monitor the Shuffleton Power Plant flume structure site and
control sites for six years; three pre-project monitoring years (2011-2013) and three post-project
monitoring years (2015-2017). Snorkeling allowed us to effectively survey a variety of habitat
types and no handling of fish was required. Night surveys were undertaken to minimize the
effect the snorkeler had on the behavior of juvenile Chinook salmon. At night, juvenile Chinook
salmon typically are inactive, rest near the bottom, can be easily approached by snorkelers, and
can be accurately counted.
Five standard snorkel transects were established in the south end of Lake Washington
(Table 1; Figure 1); one along the outside edge of the flume wall (see cover photos) and four
other transects that represented a wide-range of habitat conditions in the south end of Lake
Washington. Two of the other transects are also part of the WDNR shoreline and were part of
the restoration project (Figures 1 & 2). The last two transects were in Gene Coulon Park (City of
Renton) and were used as control sites. Length of transects was based on easily recognizable
landmarks (e.g., edge of piers) and obvious changes in habitat type (e.g., edges of logjams and
abrupt changes in substrate size).
Transects were snorkeled twice a month from late January to early June for a total of ten
surveys. Snorkelers swam parallel to the shore along the 0.4-m depth contour for shallow, non-
armored transects. Because the armored transects had a vertical wall, the snorkeler swam
parallel to the vertical wall and approximately 1 m from it so that fish close to the wall could be
easily observed. Because juvenile Chinook salmon typically inhabit water less than 1-m deep
and close to shore (Tabor et al. 2011a), we felt that surveys of both non-armored and armored
shorelines provided a good estimate of the abundance of juvenile Chinook salmon in that general
area. Transect widths were standardized at 2.5 m for shallow, non-armored transects (0.4 m) and
2.0 m for armored, deep transects. Snorkelers visually estimated the transect width and
calibrated their estimation at the beginning of each survey night by viewing a pre-measured staff
underwater.
Snorkeling began shortly after sunset (45 min to 1 h after posted sunset time). Snorkelers
used an underwater flashlight to observe the fish. All fish were counted and identified to species
or lowest taxonomic category that could be determined accurately through snorkeling (e.g.,
cutthroat trout [O. clarkii] and rainbow trout [O. mykiss] were grouped together as trout). We
also recorded separate counts for different life stages (juvenile, subadult, adult). Sculpin (Cottus
spp.) were divided into those less than and greater than 75 mm total length (TL). Sculpin in
Lake Washington consist of two species, coastrange sculpin (C. aleuticus) and prickly sculpin
(C. asper) (Tabor et al. 2007); however, we made no attempt to distinguish the two species.
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FIGURE 1.— Location of five transects (#’s 1-5) and three logjams (A-C) used to monitor abundance of juvenile
Chinook salmon in the south end of Lake Washington, January-June 2011-2017. Transect numbers correspond to
numbers in Table 1. The land adjacent to transect #’s 1-3 and logjam A-C is WDNR property. The developed
property to the southeast of WDNR property is The Boeing Company property. Transects #’s 4 and 5 are in City of
Renton’s Gene Coulon Park. ELJ = engineered logjam; NLJ = natural logjam.
1
4
5
2
3
ELJ-A
NLJ-B
ELJ-C
Lake
Washington
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FIGURE 2.— Before and after photos of the cove snorkel transects. In the upper photo, part of the cove -cobble
transect is in the foreground, the cove-sand transect is in the upper right, and the flume structure can be seen in the
background. In the lower photo, part of the old cove-sand transect is in the foreground and an engineered logjam
(ELJ-A) can be seen in the background.
Before – Jan. 2013
After – Jan. 2015
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On each survey night, we also took a water temperature (oC) and a Secchi depth (m)
measurement at the boardwalk between transects #’s 4 and 5. Water temperatures were taken at
0.5 m depth near the shoreline. A dive light was used to observe the Secchi disc (0.2-m diameter
disc with alternating black and white quadrants). Preliminary measurements indicated taking
Secchi depth measurements at night with a dive light gave similar results as taking them during
the day.
TABLE 1.— Names and habitat characteristics of five snorkel transects in the south end of Lake Washington,
January-June 2011-2013 and 2015-2017. Transect measurements were taken in 2011 and 2015. Highlighted cells in
yellow indicate changes in 2015-2017 from 2011-2013. GC = Gene Coulon Park (City of Renton). The depth was
taken along the midpoint of each transect. The distance offshore is the distance from the shoreline to the midpoint
of each transect.
Initial habitat information (substrate and slope) was collected in 2011 to help characterize
each transect (Table 1). Habitat conditions did not appear to have changed from 2011 to 2013
and no additional habitat information was collected. In 2015, we measured the flume and cove
transects again to determine how the habitat had changed as a result of the restoration project.
For each transect, we established three to five equal-spaced measurement lines that ran
perpendicular from shore. At each measurement line, water depth was measured every 2 m from
shore until the water depth was 1 m. Also at 0.5 m depth of each measurement line, we
estimated the substrate composition within a 1-m-diameter circle around that point.
Logjam Surveys
Snorkel surveys of logjams (i.e., large woody debris piles) were also conducted in 2016
and 2017. The surveys consisted of a single transect around the outside perimeter of three
logjams. Two of the logjams were engineered logjams (ELJ-A and ELJ-C) with several large
Pre-project 2011-2013
Transect Armored Distance
#Transect name shore?Length (m)Width (m)Depth (m)offshore (m)Substrate
1 Flume Yes 100 2.0 2.5 - 4.7 1 100% steel wall
2 Cove-sand No 45 2.5 0.4 2 - 5 100% sand
3 Cove-cobble No 34 2.5 0.4 4 - 6 88% cobble, 12% gravel
4 GC bulkhead Yes 57 2.0 0.4 - 0.9 1 - 2 10% sand, 26% gravel, 48% cobble, 16% cement wall
5 GC swim beach No 140 2.5 0.4 8 - 12 100% sand
Post-project - 2015-2017
Transect Armored Distance
#Transect name shore?Length (m)Width (m)Depth (m)offshore (m)Substrate
1 Old flume site No 100 2.5 0.4 2 - 3 30% sand, 70% gravel
2 Old cove-sand site No 45 2.5 0.4 2 - 4 30% sand, 70% gravel
3 Old cove-cobble site No 34 2.5 0.4 2 - 3 30% sand, 70% gravel
4 GC bulkhead Yes 57 2 0.4 - 0.9 1 - 2 10% sand, 26% gravel, 48% cobble, 16% cement wall
5 GC swim beach No 140 2.5 0.4 8 - 12 100% sand
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overlapping pieces (Figure 3) while the third logjam was a small natural logjam (NLJ-B)
consisting only of a few pieces of wood. The restoration project also included one additional
ELJ located at the east end of the restoration area but we did not survey this ELJ because water
visibility was consistently poor due to a nearby outflow pipe. Logjam surveys were conducted at
night on the same dates as our standard snorkel transects. We observed fish from the shoreline
on one side of the logjam to the outside edge of the logjam and then back to the shoreline on the
opposite side of the logjam. Maximum depth on the outside edge of the logjam varied from 0.75
to 0.8 m in February and March to 1.2 to 1.4 m in May and June. For each transect, we were
able to effectively observe fish throughout the water column. The length of the logjam transects
varied with lake level: ELJ-A 15 to 26 m, NLJ -B 7 to 14 m, and ELJ-C 32 to 40 m. Transect
width was 2 m. Because of the complexity of the logjams, we were not able to observe the inner
parts of each logjam and we assume our fish counts are an underestimate of the actual number
present.
FIGURE 3.— Photo of a newly constructed engineered logjam (ELJ-A, January 15, 2015). From January to
June, the lake level rises approximately 0.6 m to inundate much of the logjam shown.
Data Analysis
Our basic study design was a BACI (before-after-control-impact) design (Stewart-Oaten
et al. 1986). The difference in Chinook salmon density between a restoration (i.e., impact)
transect and a control transect was determined for each sample night (Stewart-Oaten et al. 1986;
Smith et al. 1993). Mann-Whitney U tests were used to compare Chinook salmon density at
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each set of restoration and control transects (Smith et al. 1993). Additionally we calculated a
combined Chinook salmon density for restoration transects (all three restoration transects pooled
together) and compared it to each control transect as well as a combined control transect. Nights
that had zeros in both the restoration and control transects were not included in the analysis
(Smith et al. 1993).
To compare Chinook salmon abundance between logjams, we used a Friedman two-way
analysis of variance test (a nonparametric repeated measure ANOVA) (Systat 2009). Data from
2016 and 2017 were pooled together to provide an adequate sample size.
Results
Ten nighttime standard snorkel surveys were completed each year except in 2011 and
2013 when only nine surveys were completed (Appendices A-1 to A-5). Poor visibility
conditions in late January 2011 and early May 2013 forced us to skip two surveys. Water
visibility and weather conditions were adequate for conducting snorkel surveys on all other
survey nights; however, we were not only able to do some surveys at the Gene Coulon swim
beach in May or June due to poor visibility conditions (presumably due to human swimming
activity during the day). During 2016 and 2017 surveys, logjam surveys were also conducted
(Appendices B-1 and B-2).
Water temperatures and Secchi depth reading were often variable between years but there
did not appear to be any strong overall difference between pre- and post-project monitoring years
(Figure 4). For water temperature, an ANCOVA (analysis of covariance) and Tukey’s multiple
comparison tests indicated the only comparison that was marginally statistically different was
between two post-project years: 2015 and 2017 (P = 0.06). Secchi readings among years were
not statistically different (one-way ANOVA, P = 0.915).
Juvenile Chinook salmon.— In comparison to the pre-project monitoring years (2011-
2013), substantially more juvenile Chinook salmon were observed along the old flume transect in
the post-project monitoring years 2015-2017 (Figure 5). A total of 791, 1,533, and 1,093
juvenile Chinook salmon were observed along the old flume transect in 2015, 2016 and 2017,
respectively. In comparison, at the same site, only 39 were observed in 2011, 98 in 2012, and
227 in 2013. A peak number of 414 juvenile Chinook salmon (1.66 fish/m2) were observed
along the old flume transect on February 16, 2016. The mean number of juvenile Chinook
salmon observed along the flume transect (January to May) was significantly higher for the years
after the restoration than before (t-test assuming unequal variances, P = 0.048). For the other
four standard snorkel transects, there was no significant difference in the mean number of
juvenile Chinook salmon observed (January to May) among the years before and after the
restoration project.
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Differences in the density of Chinook salmon between the flume transect and each of the
control transects as well as the combined control transect were significantly greater after the
restoration project than before (Table 2; Figures 6, 7 & 8), thus indicating a positive effect of the
restoration project. The cove-cobble and the combined restoration transect also showed a
positive effect of the restoration project when compared to the Gene Coulon bulkhead control but
not to the Gene Coulon swim beach control. In contrast, the cove-sand showed a negative effect
of the restoration project when compared to the Gene Coulon swim beach control but not to the
Gene Coulon bulkhead control.
FIGURE 4.— Temperature (oC) and Secchi depth (m) measurements at Gene Coulon Park, January to June 2011-
2013 (dashed lines - pre-project monitoring) and 2015-2017 (solid lines - post-project monitoring). Measurements
were taken on the boardwalk between transects #’s 4 and 5.
0
5
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Te
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FIGURE 5.— Density (fish/m2) of juvenile Chinook salmon at five transects in the south end of Lake
Washington, January-June 2011-2013 and 2015-2017. Restoration transects are dashed lines while control transects
are solid lines. Pre-project monitoring was conducted in 2011-2013 and post-project monitoring in 2015-2017. GC
= Gene Coulon Park.
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During the 2017 surveys, there was a notable outlier when 140 (0.98 fish/m2) juvenile
Chinook salmon were observed along the Gene Coulon bulkhead control transect on February 21
(Figures 5 & 6). This density was roughly 3 to 100 times higher than what was observed at this
transect on other surveys. Why so many juvenile Chinook salmon were present on February 21,
2017 is unclear; however, many were near an outflow pipe from the park and recent heavy rain
events may have attracted them to this area (Tabor et al. 2011b).
TABLE 2.— Results of statistical tests (Mann-Whitney U tests) to compare the differences in Chinook salmon
densities between restoration and control transects, south Lake Washington, January-June 2011-2013 (pre-project)
and 2015-2017 (post-project). Significant P-values (P < 0.05) are in bold. The combined restoration transect is
based on pooled data from the three restoration sites and the combined control transect is based on pooled data from
the two control transects.
Control transect Restoration transect Pre-project Post-project Pre-project Post-project U -statistic P -value
Gene Coulon bulkhead Flume 28 30 502 1,209 744 < 0.001
Gene Coulon bulkhead Cove-cobble 26 29 581 959 524 0.013
Gene Coulon bulkhead Cove-sand 28 30 925.5 785.5 320.5 0.122
Gene Coulon bulkhead Combined 28 30 668 1,043 578 0.014
Gene Coulon swim beach Flume 28 27 546 994 616 < 0.001
Gene Coulon swim beach Cove-cobble 28 27 701 839 461 0.162
Gene Coulon swim beach Cove-sand 28 27 907 633 255 0.038
Gene Coulon swim beach Combined 28 27 695 845 467 0.134
Combined Flume 28 27 531 1,009 631 < 0.001
Combined Cove-cobble 28 27 698 842 464 0.148
Combined Cove-sand 28 27 903 637 259 0.045
Combined Combined 28 27 634 906 528 0.012
Sample size Rank sumsComparison
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FIGURE 6.— Differences in juvenile Chinook salmon densities between restoration transects (including a
combined restoration transect value) and the Gene Coulon bulkhead control transect, January-June 2011-2013 and
2015-2017. Pre-project monitoring was conducted in 2011-2013 (solid symbols) and post-project monitoring in
2015-2017 (open symbols). The combined values are pooled values from the three restoration sites.
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Cove-sand Combined
Date
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FIGURE 7.— Differences in juvenile Chinook salmon densities between restoration transects (including a
combined restoration transect value) and the Gene Coulon swim beach control transect, January-June 2011-2013 and
2015-2017. Pre-project monitoring was conducted in 2011-2013 (solid symbols) and post-project monitoring in
2015-2017 (open symbols). The combined restoration transect values are pooled values from the three restoration
sites.
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FIGURE 8.— Differences in juvenile Chinook salmon densities between restoration transects (including a
combined restoration transect value) and the combined control transect (Gene Coulon swim beach and bulkhead
transects combined), January-June 2011-2013 and 2015-2017. Pre-project monitoring was conducted in 2011-2013
(solid symbols) and post-project monitoring in 2015-2017 (open symbols).
Surveys of logjams indicated the highest densities of juvenile Chinook salmon were from
February to April (Figure 9) and during this period, densities were substantially higher than in
the nearby standard open shoreline transects (Figure 10). Chinook salmon appeared to be
concentrated in the shallow waters (typically in water that was less than 0.5 m deep) on the
perimeter of each logjam (Figure 11). The larger logjams (ELJs A and C) usually had
significantly higher densities of juvenile Chinook salmon than the small logjam NLJ -B (Figure
10; Friedman test, P = 0.005; Freidman multiple comparisons test table: ELJ-A=ELJ-C, ELJ-A
and ELJ-C > NLJ-B). In May and June, densities of juvenile Chinook salmon in the logjams
decreased sharply and were typically less than the densities in the nearby standard open shoreline
transects (Figure 10).
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FIGURE 9.— Density (fish/m2) of juvenile Chinook salmon at three logjams, January-June 2016 and 2017.
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FIGURE 10.— Comparison of the density (fish/m2) of juvenile Chinook salmon along WDNR open beach
transects (old cove-cobble, old cove-sand, and old flume transects combined) and three logjams combined, January-
June 2016 and 2017.
FIGURE 11.— Photo of a group of juvenile Chinook salmon at ELJ -C (March 6, 2017). Although the photo was
taken at night, their behavior resembles more of daytime behavior: active, not closely associated with the substrate,
and displaying some schooling behavior. Artificial lighting from the adjacent Boeing facility was likely affecting
their behavior. See discussion section of this report for more information.
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Threespine stickleback.— For all standard snorkel transects combined, a total of 7,053
threespine stickleback (Gasterosteus aculeatus) were observed during pre-project years;
however, only 251 were observed during post-project years (83 in 2015, 167 in 2016, and 1 in
2017; Figure 12). The peak yearly threespine stickleback count was 4,952 in 2013 whereas only
one was observed in 2017. Because all standard transects displayed the same sharp decline
between pre- and post-restoration years, it would be difficult to detect any restoration effect on
the abundance of threespine stickleback. Few threespine stickleback were usually observed in
January through March; however, in 2013, they were commonly observed in all months. An
additional 61 threespine stickleback were observed while surveying the three logjams in 2016
but none were observed in 2017.
FIGURE 12.— Mean density (fish/m2) of threespine stickleback along five standard snorkel transects in the south
end of Lake Washington, January-June 2011-2013 and 2015-2017. GC = Gene Coulon Park.
Sculpin.- The density of sculpin was generally low in January and February and then
increased in later months as water temperatures rose. Peak abundance usually occurred in May.
Substantially more sculpin were observed along the old flume transect in 2015 through 2017 than
in earlier survey years (Figure 13); however, we likely severely underestimated their abundance
in the earlier surveys because the transect water depth was much deeper and we were usually
unable to observe the bottom.
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2011 2012 2013 2015 2016 2017
Me
a
n
f
i
s
h
/
m
2
Flume site
Cove-sand site
Cove-cobble site
GC bulkhead
GC swim beach
18
FIGURE 13.— Mean density (fish/m2) of sculpin (prickly sculpin and coastrange sculpin combined) along five
standard snorkel transects in the south end of Lake Washington, January-June 2011-2013 and 2015-2017. GC =
Gene Coulon Park.
Other Fishes.— The total number of sockeye salmon (O. nerka, fry and juveniles) varied
widely among years from 23 in 2016 to 3,487 in 2013. The number of sockeye salmon along the
cove-cobble transect decreased from a total of 1,418 (range, 77-1,131) for pre-project years to a
total of only 12 (range, 2-6) for post-project years; however, the Gene Coulon swim beach
transect showed the same trend albeit not as pronounced (range: pre-project 92-1,777; post-
project 21-71). Small numbers of trout were also observed. Based on other nearshore sampling
in Gene Coulon Park, we assumed trout were most likely cutthroat trout. Most trout were
observed during the May and June surveys and almost half of the observed trout were observed
along the Gene Coulon swim beach transect.
The combined abundance of nonnative centrarchid fishes (pumpkinseed [Lepomis
gibbosus], bluegill [L. macrochirus], rock bass [Ambloplites rupestris], smallmouth bass,
largemouth bass [M. salmoides], and black crappie (Pomoxis nigromaculatus]) in all five
transects was higher in 2015 and 2016 than in other survey years (Figure 14). Most of the
centrarchid fishes were juveniles. The higher abundances in 2015 and 2016 may have been due
in part to higher than average water temperatures (Figure 4). The other nonnative fish species
that was often encountered was yellow perch (Perca flavescens; n = 354).
Abundance of nonnative warmwater fishes (centrarchids and yellow perch) along the
standard and logjam snorkel transects was generally low in February and March but increased in
April through June (Figures 15 and 16) as water temperatures increased. The larger, more
structurally complex ELJs (A and C; Figure 17) had larger populations of nonnative fish when
compared to the smaller and shallower NLJ -B. Most of the subadult and adult warmwater fish
were often observed where the water column depths were > 0.5 m. Additionally, yellow perch
egg masses were occasionally observed on the ELJs in May.
0
0.05
0.1
0.15
0.2
0.25
0.3
2011 2012 2013 2015 2016 2017
Me
a
n
f
i
s
h
/
m
2
Flume site
Cove-sand site
Cover-cobble site
GC bulkhead
GC swim beach
19
FIGURE 14.— Mean density (fish/m2) of three types of nonnative centrarchids at five transects in the south end
of Lake Washington, January-June 2011-2013 and 2015-2017. Sunfish (Lepomis spp.) includes pumpkinseed,
bluegill, and unidentified juvenile sunfish. GC = Gene Coulon Park.
Sunfish (Lepomis spp.)
0
0.01
0.02
0.03
0.04
0.05
Me
a
n
f
i
s
h
/
m
2
0
0.02
0.04
0.06
0.08
0.1
0.12
Me
a
n
f
i
s
h
/
m
2 Flume site
Cove-sand site
Cove-cobble site
GC bulkhead
GC swim beach
Smallmouth Bass
0
0.02
0.04
0.06
0.08
0.1
0.12
2011 2012 2013 2015 2016 2017
Me
a
n
f
i
s
h
/
m
2
Rock Bass
20
FIGURE 15.— Density (fish/m2) of three types of nonnative centrarchids and yellow perch along three logjam
transects (ELJs A and C and NLJ-B), January-June 2016 and 2017. Sunfish (Lepomis spp.) includes
pumpkinseed, bluegill, and unidentified juvenile sunfish.
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Fi
s
h
/
m
2 2016
2017
Sunfish (Lepomis spp.)
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
Fi
s
h
/
m
2
Rock Bass
0
0.05
0.1
0.15
0.2
0.25
Fi
s
h
/
m
2
Smallmouth Bass
0
0.05
0.1
0.15
0.2
0.25
0.3
Fi
s
h
/
m
2
Yellow Perch
Jan Feb Mar Apr May Jun
Month
21
FIGURE 16.— Comparison of the density (fish/m2) of juvenile Chinook salmon along logjam transects and
warmwater fishes along logjam and open shoreline transects (old cove-cobble, old cove-sand, and old flume
transects combined), January-June 2016 and 2017.
0
1
2
3
4
5
6
Fi
s
h
/
m
2
2016
0
1
2
3
Fi
s
h
/
m
2
Month
2017 Chinook salmon - Logjams
Warmwater fishes - Logjams
Warmwater fishes - Open shoreline
Jan Feb Mar Apr May Jun
22
FIGURE 17.— Examples of warmwater fishes observed at logjams (photos A-C; June 2017) and Gene Coulon
bulkhead transect (photo D; June 2012). Photos A and B are of rock bass, photo C is of a smallmouth bass, and
photo D is of a pumpkinseed. All photos were taken at night along snorkel transects.
A
C
B
D
23
Discussion
Because good numbers of juvenile Chinook salmon (i.e., > 40 fish on each survey night
from January to mid-May in 2015-2017) were observed along the flume transect and their
density was similar or higher than control sites, removal of the flume structure and replacing it
with a gravel/sand beach appeared to create valuable habitat for juvenile Chinook salmon. This
site should be particularly valuable for juvenile Chinook salmon because it is close to the mouth
of the Cedar River, the source from which large numbers of Chinook salmon fry emigrate in the
winter and early spring. The old flume wall structure was a good example of a suboptimal
habitat: little shallow water with no sand and gravel substrates (Tabor et al. 2011a).
The abundance of Chinook salmon along the flume transect (outside wall) before the
restoration project was consistently low; however, we were unable to survey the entire flume
structure because of high turbidity and potentially hazardous water quality conditions inside the
structure. We assumed few juvenile Chinook salmon were using this area based on the poor
habitat and water quality conditions. Inside the flume, water was always turbid with a rust color
and looked quite different than surrounding areas. There was more structural complexity inside
the flume than outside but the vertical walls limited the amount of available shallow water
habitat. During our snorkel surveys in this study and other studies (Tabor et al. 2011a), we
generally observed that when juvenile Chinook salmon are present along vertical walls, they are
usually present near the water surface and next to the wall. We commonly conducted surface
observations to look for juvenile Chinook salmon inside the flume and rarely saw any. Even if
we assume the total number of Chinook salmon inside and outside of the flume was two to three
times what we observed outside the wall, the restoration project would still have a positive effect
because there was roughly nine times as many Chinook salmon observed along the flume
transect after the restoration project than before the project. In addition, the overall post-project
estimate would be substantially higher if the large numbers of Chinook salmon present in the
ELJs were added to the total.
Another potential complicating factor in our assessment was artificial nighttime lighting.
Removal of some trees appears to have increased the amount of artificial lighting reaching the
nearshore area from a large, nearby Boeing building. Our initial measurements indicated that
light intensity levels were elevated above ambient conditions at the restoration site; however, the
exact amount of increase from pre-project conditions is unknown because no light measurements
were taken during pre-project monitoring. In addition, Boeing replaced the upper lights (high-
pressure sodium lights to LED lights) on their large, nearby building prior to our 2017 surveys
and the light intensity was increased (Table 3). How much the increased light is affecting the
abundance of juvenile Chinook salmon is also unknown; however, recent light experiments in
Lake Washington and Lake Sammamish have indicated that juvenile Chinook salmon are
attracted to artificial nighttime lighting (Tabor et al. 2017). We did not notice any obvious
difference in Chinook salmon abundance in 2017 from 2016 or 2015 but we did notice a
noticeable change in their behavior. Instead of being inactive, close to the substrate, and not
24
associated with other fish (Figure 18), their behavior resembled more of daytime behavior:
active, not closely associated with the substrate, and displaying some schooling behavior (Figure
11). On one occasion in 2017, we also noticed large numbers of sockeye salmon fry a little
further offshore (where the water depth was 1 to 1.5 m deep) from the flume transect. Sockeye
salmon fry display a strong attraction to artificial nighttime lighting (Tabor et al. 2004; Tabor et
al. 2017).
FIGURE 18.— Photos of juvenile Chinook salmon at night. These fish are displaying typical nighttime behavior:
inactive, close to the substrate, and not associated with other fish. The top left photo was taken in February 2012,
top right in March 2017, and the bottom photo in June 2017. The top two photos were taken at the Gene Coulon
swim beach while the bottom photo was taken at ELJ-A.
The major concern of artificial nighttime lighting for Chinook salmon and other
subyearling salmonids is the potential to increase predation risk (Tabor et al. 2004; Tabor et al.
2017). Of particular concern in Lake Washington is predation by great blue herons (Ardea
herodias). During the 2017 surveys, a great blue heron was often observed near the ELJ at the
east end of the restoration site where large numbers of juvenile Chinook salmon were likely
present. This shoreline-oriented predator has often been seen feeding in other artificially lit areas
in Lake Washington and Lake Sammamish (Tabor et al. 2017). They are a large predator with a
high energetic demand and are capable of consuming large numbers of fish. Any reduction to
25
light intensity levels will likely be beneficial. As the recently planted trees grow, the effect of
artificial nighttime lighting should also be reduced.
TABLE 3.— Light intensity readings taken in 2015, 2016, and 2017. All readings were taken at the water edge .
Transects and locations are listed from west to east. Readings taken in 2015 were taken with an International Light
photometer (model IL 1440A), while those in 2016 and 2017 were taken with an Extech Instrument light meter
(model 104036).
Besides having a strong effect on the number of Chinook salmon using the flume site, the
restoration project also had a moderate effect on the other two transects (cove-cobble and cove-
sand). The restoration project had a positive effect on the cove-cobble transect while a negative
effect on the cove-sand transect. Changes in Chinook salmon use were most likely due to
changes in substrate size. The cove-cobble had a reduction in substrate size (cobble/gravel to
gravel/sand) while the cove-sand site had an increase in substrate size (sand to gravel/sand; Table
1). Previous studies have also found that juvenile Chinook salmon in Lake Washington and
other lentic systems primarily use small substrates (Curet 1993; Johnson et al. 2007; Tabor et al.
2011a).
The strong association of Chinook salmon with sand and gravel may also be related to
slope preference, at least in part, because slope and substrate are usually correlated. Both Tiffan
et al. (2002) and Sergeant and Beauchamp (2006) found juvenile Chinook salmon often select
gentle slopes. The change in substrate size at the cove-cobble and cove-sand sites provided a
good test of the importance of substrate size for juvenile Chinook salmon because it is difficult to
determine if Chinook salmon abundance is related to substrate size and not just due to the slope.
The cove-cobble and the cove-sand sites had the substrate altered while the slope remained about
the same. Results indicated that changing the substrate size to gravel/sand from cobble (cove-
cobble transect) increased the abundance of juvenile Chinook salmon while changing the
Transect Location 8-Apr-15 23-May-16 6-Feb-17 6-Mar-17
ELJ-C West side 0.6 2.1 1.42
ELJ-C East side 1.6 3.4 2.25
NLJ-B Middle 1.6 3.6 2.85
3 Middle of transect 2.9 4.1
3 W 1/3 of transect 2.636 4.03
3 E 1/3 of transect 0.84 3.44
2 W 1/3 of transect 0.537 2.4 2.8 2.4
2 E 1/3 of transect 0.118 0.4 1 1.35
ELJ-A West side 1.42
ELJ-A East side 0.4 1.1 0.95
1 W 1/3 of transect 0.204 0.3 1.4 1.27
1 E 1/3 of transect 0.07 0.1 1.4 1.38
5 Middle of transect 0.1 0.15
Date
26
substrate from sand to gravel/sand (cove-sand transect) decreased the abundance of juvenile
Chinook salmon. While this was not a comprehensive test of this hypothesis, it does provide
additional evidence that substrate size is an important variable in their habitat selection.
Our first assessment of the logjams was completed in 2016. In 2015, we attempted to
assess logjams through daytime snorkeling observations but juvenile Chinook salmon were often
difficult to observe because of poor visibility and it was difficult to see fish inside of the logjam.
In 2016, we switched to nighttime snorkeling observations. Based on previous snorkeling efforts
(Tabor et al. 2011a), we expected juvenile Chinook salmon would move away from the logjams
at night and it would be difficult to determine Chinook salmon use of these structures. However,
it appeared they only moved a short distance away (< 2 m) from the structure and were
concentrated on the outside perimeter.
Nighttime surveys of logjams indicated large numbers of Chinook salmon are often
closely associated with these structures. Based on nighttime surveys in 2016 and 2017, a few
daytime surveys in 2015, and other observations (Tabor et al. 2011a), it appears juvenile
Chinook salmon are primarily in small schools in the middle of the logjam during the day and
then move to the outside perimeter of the logjam at night to rest on the bottom. The degree that
juvenile Chinook salmon forage in the logjam is unknown. Koehler (2002) found that, among
various Lake Washington shoreline types, natural forested shorelines with overhanging
vegetation had the lowest densities of chironomids (the main forage item of juvenile Chinook
salmon); therefore, logjams may not have higher levels of prey abundance than other sites.
There are likely times (e.g., dawn and dusk) when some juvenile Chinook salmon move away
from logjams to forage. Likely, the most important function of logjams is to provide juvenile
Chinook salmon refuge from predators.
Among the logjams, the large ELJs consistently had Chinook salmon densities that were
2 to 10 times higher than the small NLJ-B. The use of large overlapping pieces of woody debris
appears to provide ample structural complexity and overhead cover (Figure 3). Although we
only surveyed one NLJ, our results are consistent with other surveys. In Lake Quinault, the
highest concentrations of juvenile Chinook salmon during the day were directly under large
pieces of woody debris (Tabor et al. 2006). Also, rootwads (similar to NLJ-B in this study) used
at the Chinook Beach Park (City of Seattle park at Rainier Beach) restoration project were not
used extensively by juvenile Chinook salmon (R. Tabor, personal observation). Each of these
rootwads was laid flat on the bottom and there was little overhead cover.
The logjams appeared to provide valuable habitat for juvenile Chinook salmon but may
also provide habitat for nonnative centrarchids including smallmouth bass. However,
centrarchids we observed were mostly juveniles and too small to predate on juvenile Chinook
salmon. The logjams do not extend out into deep water (i.e., > 1.5 m depth) which probably
minimizes the use by subadult and adult smallmouth bass. Also, the abundance of juvenile
Chinook salmon is usually low in May and June when smallmouth bass are common in the
27
logjams. Therefore, the new ELJs likely do not directly affect juvenile Chinook salmon through
predation but could indirectly affect them by enhancing centrarchid populations.
The number of introduced centrarchid fishes (pumpkinseed, bluegill, rock bass,
smallmouth bass, and largemouth bass) observed in shoreline transects appeared to be higher in
2015 and 2016 than in the previous survey years. Several factors could account for this change.
First, the flume structure was removed and shallow water habitat is now available for juvenile
centrarchids; however, this would only account for an increase in abundance in one of the five
transects. Secondly, water temperatures were higher in 2015 and 2016 than in other survey years
and our observed centrarchid abundance in May and early June may be typical of their
abundance in late June through August in other years. Many of the centrarchids observed in
2015 were observed during our last survey on June 1. Lastly, observed increases in their
abundance may be an indication of an increase in their population size in south Lake
Washington. This may be particularly true for rock bass and bluegill which were not observed
during snorkel and electrofishing surveys of south Lake Washington in the late 1990’s (R. Tabor,
unpublished data) and may have recently colonized south Lake Washington. There has also been
some evidence of an increase of overall lake temperatures (Arhonditsis et al. 2004), which may
favor warmwater fishes such as centrarchids over cool-water fishes.
In conclusion, removal of the flume structure and replacing it with a more natural
shoreline appeared to have improved juvenile Chinook salmon habitat in Lake Washington. The
restored nearshore habitat now has a large area of shallow water < 1 m deep, primarily sand and
gravel substrate, a gentle slope, and some nearby logjams for refuge.
Acknowledgments
We wish to thank Monica Shoemaker, WDNR for all of her support throughout this
project. We thank U.S. Fish and Wildlife Service (USFWS) employees Alex Bell, Tim Grun,
Kira Mazzi, and Jennifer Fields who assisted with the field work. Kelly Beymer, Dana Appel,
and Leslie Betlach, City of Renton and Dean Torgrude and Nancy Eklund, The Boeing Company
provided logistic support. An earlier draft of this report was reviewed by Pat DeHaan, USFWS
and Monica Shoemaker. Funding for this project was made possible by WDNR and
administered by Monica Shoemaker and Jordanna Black. The findings and conclusions in this
report are those of the authors and do not necessarily reflect the views of the USFWS.
28
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Curet, T. 1993. Habitat use, food habits, and the influence of predation on subyearling Chinook
salmon in Lower Granite and Little Goose Reservoirs, Washington. Master's thesis,
University of Idaho, Moscow, Idaho.
Healey, M. C. 1991. Life history of Chinook salmon (Oncorhynchus tshawytscha). Pages 313-
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Johnson, J. E., S. P. DeWitt, and J. A. Clevenger, Jr. 2007. Causes of variable survival of
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Washington, Seattle.
Sergeant, C. J., and D. A. Beauchamp. 2006. Effects of physical habitat and ontogeny on lentic
habitat preferences of juvenile Chinook salmon. Transactions of the American Fisheries
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lakes in western Washington State. Transactions of the American Fisheries Society
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Tabor, R. A., G. S. Brown, and V. T. Luiting. 2004. The effect of light intensity on sockeye
salmon fry migratory behavior and predation by cottids in the Cedar River, Washington.
North American Journal of Fisheries Management 24:128-145.
29
Tabor, R. A., K. L. Fresh, D. K. Paige, E. J. Warner, and R. J. Peters. 2007. Distribution and
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30
Appendix A-1. Number of fish observed in 2011 along five shoreline transects in the south end
of Lake Washington. GC = Gene Coulon (City of Renton park). Length and area surveyed for
each transect is given in Table 1.
Transect Fish group Species 10-Feb 25-Feb 14-Mar 29-Mar 11-Apr 27-Apr 10-May 26-May 7-Jun Total
Flume Salmonids Chinook salmon 2 6 13 5 2 4 3 3 1 39
Sockeye salmon 42 1 3 46
Trout 1 1
Other native Sucker (juveniles)1 1
Threespine stickleback 2 9 104 53 7 33 208
Sculpin 3 2 1 6
Nonnative Smallmouth bass 1 1 2
Black crappie 1 2 4 7
Sunfish (juveniles)1 1
Cove - sand Salmonids Chinook salmon 8 65 25 56 12 42 130 15 11 364
Sockeye salmon 42 4 23 7 1 77
Trout 1 1
Other native Longfin smelt 4 4
Peamouth 1 1
Sucker (juveniles)1 5 6
Threespine stickleback 8 2 42 22 32 106
Sculpin 14 4 31 37 4 3 30 21 34 178
Nonnative Sunfish (juveniles)1 1
Pumpkinseed 1 1
Yellow perch 5 10 6 21
Cove - cobble Salmonids Chinook salmon 15 2 35 5 3 60
Sockeye salmon 1 21 22
Trout 1 1
Other native Threespine stickleback 2 4 40 15 60 121
Sculpin 10 2 37 44 1 2 25 15 4 140
Nonnative Yellow perch 5 6 5 16
GC bulkhead Salmonids Chinook salmon 1 3 6 1 1 1 3 16
Trout 1 1
Other native Threespine stickleback 23 52 65 88 95 323
Sculpin 8 2 5 24 17 27 38 42 44 207
Nonnative Smallmouth bass 1 1 2
Sunfish (juveniles)1 2 3
Rock bass 1 4 2 2 3 12
Yellow perch 1 1 3 5
GC swim beach Salmonids Chinook salmon 9 8 31 23 8 6 95 81 36 297
Sockeye salmon 11 9 9 19 4 1 3 35 1 92
Trout 2 1 1 2 6
Other native Longfin smelt 2 8 1 11
Peamouth 4 4
Sucker (juveniles)2 2
Threespine stickleback 2 2 41 134 90 125 80 474
Sculpin 25 24 19 15 14 124 111 24 356
Nonnative Smallmouth bass 9 1 10
Sunfish (juveniles)1 1
Pumpkinseed 1 1
Yellow perch 2 21 3 26
Date
31
Appendix A-2. Number of fish observed in 2012 along five shoreline transects in the south
end of Lake Washington. GC = Gene Coulon (City of Renton park). Length and area surveyed
for each transect is given in Table 1.
Transect Fish group Species 26-Jan 6-Feb 21-Feb 14-Mar 27-Mar 9-Apr 23-Apr 15-May 21-May 11-Jun Total
Flume Salmonids Chinook salmon 2 19 24 17 3 11 14 8 98
Sockeye salmon 2 1 3
Other native Longfin smelt 1 1
Peamouth 1 5 6
Threespine stickleback 1 1 180 11 4 4 201
Sculpin 1 6 3 6 1 1 18
Nonnative Smallmouth bass 2 1 2 5
Black crappie 2 2
Sunfish (juveniles)1 1
Rock bass 8 8
Yellow perch 1 1
Cove - sand Salmonids Chinook salmon 36 64 124 44 218 225 111 77 82 13 994
Coho salmon 2 1 3
Sockeye salmon 10 10 143 4 19 20 4 210
Trout 2 1 1 4
Other native Sucker (juveniles)3 3
Threespine stickleback 3 3 115 40 161
Sculpin 6 3 6 32 3 17 12 30 53 105 267
Nonnative Smallmouth bass 1 1
Yellow perch 11 11
Cove - cobble Salmonids Chinook salmon 4 31 14 3 12 12 2 15 9 102
Sockeye salmon 1 5 1 2 9
Trout 3 3
Other native Threespine stickleback 23 92 75 190
Sculpin 2 11 7 3 10 1 25 9 68
Nonnative Smallmouth bass 1 1 2
Sunfish (juveniles)2 2
Rock bass 1 1
Yellow perch 3 3
GC bulkhead Salmonids Chinook salmon 14 9 12 6 14 5 9 15 1 85
Sockeye salmon 4 4
Trout 1 1
Other native Peamouth 3 3
Threespine stickleback 1 9 31 25 48 50 164
Sculpin 9 4 9 6 22 12 17 1 32 52 164
Nonnative Largemouth bass 1 1 2
Smallmouth bass 1 1 1 1 1 1 1 7
Sunfish (juveniles)2 2
Pumpkinseed 1 1
Rock bass 2 1 5 4 12
GC swim beach Salmonids Chinook salmon 1 34 97 93 110 118 187 221 249 4 1,114
Coho salmon 1 1
Sockeye salmon 4 9 50 34 22 4 27 1 151
Trout 6 1 2 9
Other native Threespine stickleback 1 1 2 72 5 29 13 123
Sculpin 16 41 40 28 36 17 44 4 96 24 346
Nonnative Smallmouth bass 1 1 2 1 1 6
Sunfish (juveniles)1 1
Rock bass 1 1
Yellow perch 2 2
Date
32
Appendix A-3. Number of fish observed in 2013 along five shoreline transects in the south
end of Lake Washington. GC = Gene Coulon (City of Renton park). Length and area surveyed
for each transect is given in Table 1.
Transect Fish group Species 28-Jan 11-Feb 25-Feb 11-Mar 25-Mar 8-Apr 22-Apr 22-May 3-Jun Total
Flume Salmonids Chinook salmon 40 26 52 17 35 26 26 5 227
Coho salmon 9 9
Sockeye salmon 50 20 270 47 6 2 395
Other native Threespine stickleback 48 120 15 35 52 16 36 187 150 659
Sculpin 3 1 4
Cove - sand Salmonids Chinook salmon 65 76 220 113 125 182 42 1 2 826
Coho salmon 106 106
Sockeye salmon 38 3 76 160 800 30 24 1,131
Other native Longfin smelt 1 1
Peamouth 30 6 36
Sucker 6 4 10
Threespine stickleback 2 29 25 52 42 72 10 110 150 492
Sculpin 4 8 17 4 6 44 12 19 114
Nonnative Smallmouth bass 1 1 2
Sunfish (juveniles)3 3
Yellow perch 1 2 1 2 10 15 31
Cove - cobble Salmonids Chinook salmon 0 14 74 72 30 50 4 244
Sockeye salmon 28 57 15 15 2 117
Other native Threespine stickleback 2 27 33 59 67 39 20 73 75 395
Sculpin 10 8 5 18 3 2 46
Nonnative Black crappie 1 1
Yellow perch 4 4
GC bulkhead Salmonids Chinook salmon 1 12 4 28 19 8 9 12 93
Sockeye salmon 1 12 3 20 27 3 1 67
Other native Threespine stickleback 80 108 42 55 157 107 57 238 300 1,144
Sculpin 2 11 3 4 1 11 7 11 15 65
Nonnative Smallmouth bass 7 4 2 8 9 4 5 2 41
Sunfish (juveniles)2 2
Rock bass 2 5 4 3 11 9 8 8 6 56
Yellow perch 3 3
GC swim beach Salmonids Chinook salmon 24 31 78 214 166 72 47 35 45 712
Coho salmon 1 4 5
Sockeye salmon 6 73 25 741 870 27 13 10 12 1,777
Trout 1 4 5
Other native Longfin smelt 1 3 4
Peamouth 1 1
Sucker 2 2
Threespine stickleback 215 172 602 740 167 56 235 75 2,262
Sculpin 35 5 27 40 40 55 32 16 17 267
Nonnative Smallmouth bass 2 2 4
Rock bass 1 1
Yellow perch 3 5 2 8 9 27
Date
33
Appendix A-4. Number of fish observed in 2015 along five shoreline transects in the south
end of Lake Washington. Length and area surveyed for each transect is given in Table 1.
Transect Fish group Species 22-Jan 9-Feb 19-Feb 9-Mar 23-Mar 8-Apr 20-Apr 6-May 18-May 1-Jun Total
Old flume Salmonids Chinook salmon 47 104 146 98 141 89 60 46 60 791
Coho salmon 3 4 2 9
Sockeye salmon 1 2 3
Trout 2 2 4
Other native Peamouth 1 1
Threespine stickleback 1 1 7 11 2 2 4 28
Sculpin 3 6 8 1 24 44 39 38 40 66 269
Nonnative Largemouth bass 3 1 4
Smallmouth bass 1 2 1 3 1 21 29
Rock bass 1 1 2 21 25 83 120 253
Sunfish (juveniles)54 7 16 2 5 1 5 6 59 120 275
Pumpkinseed 3 3
Yellow perch 1 1 2 4 4 12
Old cove-sand Salmonids Chinook salmon 42 56 96 30 104 50 32 23 18 4 455
Coho salmon 6 1 7
Sockeye salmon 2 1 2 1 6
Trout 1 2 3
Other native Threespine stickleback 2 6 2 10
Sculpin 2 5 5 3 6 33 42 26 122
Nonnative Largemouth bass 2 2
Smallmouth bass 1 1 2 2 9 15
Rock bass 1 16 17
Sunfish (juveniles)1 1 14 16
Bluegill 1 1 2
Pumpkinseed 1 1
Yellow perch 1 2 2 5
Old cove-cobble Salmonids Chinook salmon 38 68 84 12 31 25 25 21 38 342
Coho salmon 5 5
Sockeye salmon 1 1 2 4
Trout 1 1
Other native Threespine stickleback 1 2 1 4
Sculpin 4 2 9 10 30 10 65
Nonnative Rock bass 1 1 2
Sunfish (juveniles)13 13
Pumpkinseed 4 4
Black crappie 3 3
Yellow perch 1 1 4 6
GC bulkhead Salmonids Chinook salmon 3 24 1 4 4 4 40
Trout 3 2 1 6
Other native Threespine stickleback 4 1 9 6 1 21
Sucker 1 1
Sculpin 1 3 5 14 29 30 17 9 7 20 135
Nonnative Largemouth bass 2 2 2 1 7
Smallmouth bass 8 4 3 7 3 1 1 6 33
Rock bass 3 3 13 1 9 12 9 8 6 25 89
Sunfish (juveniles)1 1 4 5 1 40 52
Bluegill 4 3 12 19
Pumpkinseed 1 6 10 17
Yellow perch 1 2 3 1 7
GC swim beach Salmonids Chinook salmon 16 41 18 34 65 45 9 35 6 2 271
Coho salmon 2 2
Sockeye salmon 3 2 2 7 6 3 11 1 35
Trout 6 1 1 4 1 1 14
Other native Peamouth 2 2 4
Threespine stickleback 2 2 12 1 2 1 20
Sculpin 16 7 26 13 25 25 22 32 38 31 235
Nonnative Bullhead 1 1
Largemouth bass 1 2 3
Smallmouth bass 2 1 4 2 2 11 8 16 46
Rock bass 1 3 12 9 45 70
Sunfish (juveniles)1 26 27
Bluegill 1 1
Pumpkinseed 5 6 11
Yellow perch 1 2 2 10 9 24
Date
34
Appendix A-5. Number of fish observed in 2016 along five shoreline transects in the south
end of Lake Washington. Length and area surveyed for each transect is given in Table 1. ND =
no data (i.e., too turbid to survey).
Transect Fish group Species 25-Jan 16-Feb 22-Feb 7-Mar 21-Mar 4-Apr 18-Apr 10-May 23-May 6-Jun Total
Old flume Salmonids Chinook salmon 170 414 140 190 229 162 160 55 13 1,533
Trout 1 2 5 2 10
Other native Threespine stickleback 5 12 4 2 2 25
Sculpin 6 2 5 16 36 34 73 30 202
Nonnative Largemouth bass 1 2 3
Smallmouth bass 1 1 4 1 3 4 5 9 28
Rock bass 1 6 4 10 21
Sunfish (juveniles)75 12 11 1 19 48 61 82 86 113 508
Yellow perch 1 1 4 14 4 24
Old cove-sand Salmonids Chinook salmon 158 170 42 87 67 90 40 19 9 1 683
Sockeye salmon 2 2
Other native Threespine stickleback 55 22 1 78
Sculpin 3 5 37 40 30 115
Nonnative Smallmouth bass 3 2 1 6
Sunfish (juveniles)1 2 1 29 6 20 11 70
Yellow perch 1 1 10 2 9 23
Old cove-cobble Salmonids Chinook salmon 33 29 12 35 21 36 15 19 16 1 217
Coho salmon 1 1
Trout 1 1
Other native Threespine stickleback 10 8 2 20
Sculpin 2 2 23 15 6 48
Nonnative Largemouth bass 1 1
Smallmouth bass 2 3 5
Rock bass 3 1 4
Sunfish (juveniles)10 8 13 3 34
Yellow perch 2 2 1 1 5 8 39 58
GC bulkhead Salmonids Chinook salmon 19 52 24 4 11 3 5 118
Trout 1 1
Other native Threespine stickleback 4 5 1 10
Sculpin 2 1 4 21 10 14 11 7 8 6 84
Nonnative Bullhead 1 1 2
Largemouth bass 1 1 2 3 7
Smallmouth bass 8 4 6 1 7 2 1 1 1 31
Rock bass 2 19 22 6 15 64
Sunfish (juveniles)2 8 2 1 7 26 76 34 51 43 250
Yellow perch 2 2 5 2 11
GC swim beach Salmonids Chinook salmon 136 240 442 281 270 118 166 16 3 ND 1,672
Trout 7 2 3 2 ND 14
Sockeye salmon 3 3 2 3 9 1 ND 21
Other native Peamouth 1 ND 1
Threespine stickleback 1 3 28 1 1 ND 34
Sculpin 7 5 3 8 8 19 5 6 27 ND 88
Yellow perch 1 ND 1
Nonnative Largemouth bass 1 ND 1
Smallmouth bass 4 3 3 3 ND 13
Rock bass 1 1 2 2 ND 6
Sunfish (juveniles)3 4 6 3 21 ND 37
Pumpkinseed 1 ND 1
Yellow perch 2 1 3 1 ND 7
Date
35
Appendix A-6. Number of fish observed in 2017 along five shoreline transects in the south
end of Lake Washington. Length and area surveyed for each transect is given in Table 1. ND =
no data (i.e., too turbid to survey).
Transect Fish group Species 25-Jan 6-Feb 21-Feb 6-Mar 20-Mar 3-Apr 17-Apr 8-May 22-May 5-Jun Total
Old flume Salmonids Chinook salmon 216 221 118 26 63 66 66 140 125 52 1,093
Coho salmon 1 1
Trout 2 7 9
Sockeye salmon 15 34 49
Other native Sculpin 3 1 1 3 11 15 26 20 80
Nonnative Smallmouth bass 1 2 3
Rock bass 1 1
Sunfish (juveniles)1 1 2 10 14
Yellow perch 8 4 12
Old cove-sand Salmonids Chinook salmon 44 40 35 42 34 92 65 29 82 5 468
Trout 1 4 5
Sockeye salmon 3 1 4
Other native Sculpin 1 2 10 6 3 22
Sucker 1 1
Nonnative Sunfish (juveniles)6 6
Yellow perch 4 2 6
Old cove-cobble Salmonids Chinook salmon 24 17 3 30 72 64 58 16 13 4 301
Trout 1 1 2
Sockeye salmon 1 3 4
Other native Threespine stickleback 1 1
Sculpin 1 1 2 3 7
Nonnative Yellow perch 2 2
GC bulkhead Salmonids Chinook salmon 3 52 140 18 25 3 3 1 3 1 249
Trout 1 1 1 3
Sockeye salmon 4 1 5
Other native Sculpin 3 3 3 4 9 7 33 13 3 3 81
Nonnative Brown bullhead 2 2
Largemouth bass 4 2 6
Smallmouth bass 1 3 4
Rock bass 1 8 9 17 35
Sunfish (juveniles)4 1 2 1 2 5 21 27 63
Pumpkinseed 4 4
Bluegill 1 1
GC swim beach Salmonids Chinook salmon 206 98 295 146 165 54 192 88 ND ND 1,244
Trout 1 ND ND 1
Sockeye salmon 8 8 17 17 17 4 ND ND 71
Other native Sculpin 2 2 3 3 19 8 17 53 ND ND 107
Nonnative Rock bass 1 ND ND 1
Yellow perch 3 1 ND ND 4
Date
36
Appendix B-1. Number of fish observed in 2016 along the outside perimeter of three
logjams in the south end of Lake Washington. ND = no data.
Logjam Fish group Species 16-Feb 22-Feb 7-Mar 21-Mar 4-Apr 18-Apr 10-May 23-May 6-Jun Total
ELJ-A Salmonids Chinook salmon 331 144 222 253 94 37 7 1 1,089
Trout 1 1
Other native Threespine stickleback 4 7 5 5 1 22
Sculpin 1 1 2 7 17 5 12 41 11 97
Nonnative Largemouth bass 1 1 2
Smallmouth bass 1 4 7 7 24 43
Rock bass 3 3 35 30 25 33 129
Sunfish (juveniles)8 6 10 22 48 81 89 64 36 364
Pumpkinseed 1 1
Crappie 1 1
Yellow perch 1 2 14 3 1 21
NLJ-B Salmonids Chinook salmon ND 5 25 24 16 5 3 78
Trout ND 1 2 3
Other native Threespine stickleback ND 9 1 5 4 1 20
Sculpin ND 1 1 4 3 8 4 21
Nonnative Largemouth bass ND 1 1
Smallmouth bass ND 1 1 2 3 7
Rock bass ND 1 5 6
Sunfish (juveniles)ND 3 3 4 8 18
Bluegill ND 1 1
Yellow perch ND 1 10 3 2 16
ELJ-C Salmonids Chinook salmon ND 178 294 327 129 8 936
Other native Threespine stickleback ND 4 5 6 4 19
Sculpin ND 2 5 2 10 17 11 47
Nonnative Smallmouth bass ND 1 5 4 10
Rock bass ND 3 9 8 20
Sunfish (juveniles)ND 2 2 1 11 30 17 63
Yellow perch ND 4 16 1 3 24
Date
37
Appendix B-2. Number of fish observed in 2017 along the outside perimeter of three
logjams in the south end of Lake Washington.
Logjam Fish group Species 25-Jan 6-Feb 21-Feb 6-Mar 20-Mar 3-Apr 17-Apr 8-May 22-May 5-Jun Total
ELJ-A Salmonids Chinook salmon 41 74 67 82 75 79 96 24 16 5 559
Coho salmon 1 16 6 23
Sockeye salmon 3 3
Other native Sculpin 5 2 3 25 8 13 7 63
Nonnative Oriental weatherfish 1 1
Largemouth bass 1 1
Smallmouth bass 1 2 3
Rock bass 1 2 5 6 26 40
Sunfish (juveniles)3 2 1 1 6 9 25 51 98
Yellow perch 21 5 26
NLJ-B Salmonids Chinook salmon 2 3 45 6 5 8 2 71
Other native Sculpin 1 1 2 4 8
Nonnative Rock bass 1 3 4
Yellow perch 7 4 11
ELJ-C Salmonids Chinook salmon 31 39 24 184 16 95 115 13 4 521
Trout 1 1
Other native Sculpin 1 1 1 8 1 5 8 25
Nonnative Smallmouth bass 2 2
Rock bass 2 10 12
Yellow perch 3 7 10
Date