Lake Washington General Investigation
Julie Hall, Seattle Public Utilities
What I’d like to cover today…
• Study purpose
• History
• Accomplishments
• Status
• So what next?
LW GI Purpose
Identify and implement environmental restoration
projects for the Lake Washington system to:
1) improve habitat conditions for salmon and other
wildlife;
2) use water efficiently at the Locks to benefit salmon.
History of the GI
1999:
Chinook
Reconnaissance
listed
1997:
LW GI began
Seattle and
King County
local sponsors
1998:
Reconnaissance
report 905(b)
Feasibility
Split LW GI into 2 phases:
Phase 1 =
King Co.
Project formulation
Feasibility analyses
Phase 2 =
Seattle
Further
studies
LW Chinook
LW
Smolt Flume
Habitat Use Predators
Efficiency
2006:
Discontinued
Locks
Passage
Salmon
Synthesis
Report
Acoustic
Tracking
History of the GI
1999:
Chinook
Reconnaissance
listed
1997:
LW GI
Seattle and
King County
local sponsors
1998:
Reconnaissance
report 905(b)
Feasibility
Split LW GI into 2 phases:
Phase 1 =
King Co.
Project formulation
Feasibility analyses
Phase 2 =
Seattle
Further
studies
LW Chinook
LW
Smolt Flume
Habitat Use Predators
Efficiency
2006:
Discontinued
Locks
Passage
Salmon
Synthesis
Report
Acoustic
Tracking
P.Johnson: Filling
Culvert entrainment
2000-2004
R2: PIT Tagging and
Locks Passage
1998-2008
WDFW/R2: Smolt
Flume Efficiency
2002, 2004
Corps/MIT: Adult
return timing/behavior
2000, 2005-2007
LW GI Studies
USFWS: Chinook
smolt outmigration
2004-2008
USFWS: Chinook
smolt outmigration
2005-2006
WDFW: LW and
Ship Canal predators
2000-2001, 2003
USFWS: Dock
observations
2004-2006
UW: Chinook habitat
preferences
2004-2005
USFWS: Juvenile
Chinook habitat use
2000-2006
Lake Washington
Chinook fry need rearing habitat and “rest stops”
for the 3-5 months they inhabit Lake Washington
February-May
Preferred rearing habitat includes:
•
•
•
•
Shoreline areas with shallow depths (>1 m) and gentle slopes
Fine substrates
Overhanging vegetation/small woody debris
Small creeks: mouths and shallow, low gradient, upstream
portions
Density of juvenile Chinook, relative
to distance from the Cedar River
Density (fish/m2)
March – June
0.6
y = -0.13Ln(x) + 0.33
R2 = 0.79
0.4
0.2
0
0
5
10
15
Distance to Cedar River
20
Small creek mouths = highly used
Chinook / m2
Comparison of Deltas and Lake Shore
(South L.Washington and L. Sammamish)
1
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0.6
0.4
0.2
0
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From "Nearshore Habitat Use by Juvenile Chinook Salmon in Lentic Systems of the Lake Washington Basin".
Annual Report, 2002 by Roger Tabor, US Fish and Wildlife Service
To Avoid Predators, Juvenile Chinook:
Avoid areas with little light,
like under docks
Over-water structures cause
juveniles to detour to deeper
water
Avoid shorelines without shallow water
areas due to bank armoring
Bulk heading and rip rap
provide a refuge for
predators, reduce shallow
water areas, and prevent
bank sloughing (which
supplies fine sediment)
Docks affect how fish move along the
shoreline
May-June
Fish continue to move along the
shoreline, close to shore
After passing under or
around the dock, the
school moves closer to
shore
As the school approaches a
dock, the fish move offshore
into deeper water and pass
under or around the dock
Fish move in schools close to shore
(within a few meters)
Effect of structures:
• Increase distance
traveled
• Force migrating
smolts into deeper
water (increase
predation risk?)
Fish moved back
to shallower water
once beyond the
last structure
direction
of travel
Microacoustic Tracking at Tennis Club
Ship Canal and Lake Union
Tracking System
1. “Listening station”
RECEIVER
Tracking System
2. Get a fish and a tag
Tracking System
3. Track your fish
RECEIVER
Example Chinook smolt
track from Portage Bay
Gas Works 2005
All Chinook combined into one
density plot with each fish weighted
equally.
Gas Works 2005
Acoustic Results
• Behavior very different between Lake
Washington and the Ship Canal/Lake Union
• In Ship Canal, fish are widely distributed and not
just along shoreline
• Chinook smolts use south Lake Union!
• Fish appear to spend longer periods of time in
Lake Union (several days)
• Fish appear to hold/delay in Union Bay
• Predators associated with overwater structures,
steep sloping shorelines, and edge of aquatic
vegetation
Ballard
Locks
Juvenile Salmon at the Locks
Numerous projects and studies have occurred at the
Locks to increase the safety of juvenile fish passage
Removing
barnacles from
the filling culverts
Smolt slides
Pit Tagging studies
Operation of
strobe lights to
deter smolts from
entering the filling
culverts
Fish Passage and Water
Flow
Studying the amount of water needed to pass the
maximum number of smolts through the flumes
Relative Guidance Efficiency (%)
100
90
May 8
80
70
60
May 9
50
At flows > 80cfs,
> 95% of juvenile
salmon used the
flumes to pass
through the
Locks
40
30
20
10
0
0
20
40
60
80
100
120
140
Total Daytime Flume Volume (cfs)
160
180
200
Number of PIT Tagged Fish Detected/Day
Declining Detection Rates & Surface Water
Temperature at the Fremont Bridge
450
400
2001
350
2002
300
2003
250
200
150
100
50
0
11
13
15
17
19
Mean Daily Water Temperature (C)
21
23
Research
Wrap-Up
1. Synthesis report
of research due
end of 2008
2. Microacoustic
tracking report
due in 2009
LW GI Status – Both Phases
Discontinued
• Seattle, similar to King County, discontinuing
participation
– Authority does not go away
• Reasoning:
– Heavy staff and money investment in
bureaucratic process
– Uncertain future return
– Reduced priority federally
– Other avenues more cost-effective
So what is next?
• Other Corps partnership opportunities:
–
–
–
–
Section 206
Section 1135
Puget Sound and Adjacent Waters (PSAW)
Section 22 – Planning Assistance
• Biological Opinion:
Continuing and new
actions at the Locks
Salt water drain
adult excluder
Installed 6/08