Lake Washington General InvestigationJulie Hall, Seattle Public Utilities

What I’d like to cover today…

• Study purpose

• History

• Accomplishments

• Status

• So what next?

LW GI PurposeIdentify 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

1997:LW GI beganSeattle and King County local sponsors

Reconnaissance

1998: Reconnaissance

report 905(b)

Feasibility

Split LW GI into 2 phases:

1999: Chinook

listed

2006: Discontinued

Phase 1 =King Co.

Project formulationFeasibility analyses

Phase 2 =Seattle

Further studies

LW Chinook Habitat Use

LW Predators

Smolt Flume Efficiency

Locks Passage

Acoustic Tracking

Salmon Synthesis

Report

History of the GI

1997:LW GISeattle and King County local sponsors

Reconnaissance

1998: Reconnaissance

report 905(b)

Feasibility

Split LW GI into 2 phases:

1999: Chinook

listed

2006: Discontinued

Phase 1 =King Co.

Project formulationFeasibility analyses

Phase 2 =Seattle

Further studies

LW Chinook Habitat Use

LW Predators

Smolt Flume Efficiency

Locks Passage

Acoustic Tracking

Salmon Synthesis

Report

USFWS: Juvenile Chinook habitat use2000-2006

USFWS: Chinook smolt outmigration2005-2006

LW GI Studies

WDFW: LW and Ship Canal predators2000-2001, 2003

UW: Chinook habitat preferences2004-2005

USFWS: Dock observations2004-2006

USFWS: Chinook smolt outmigration2004-2008

WDFW/R2: Smolt Flume Efficiency2002, 2004

P.Johnson: Filling Culvert entrainment2000-2004

R2: PIT Tagging and Locks Passage1998-2008

Corps/MIT: Adult return timing/behavior2000, 2005-2007

Lake Washington

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

Chinook fry need rearing habitat and “rest stops” for the 3-5 months they inhabit Lake Washington

February-May

Density of juvenile Chinook, relative to distance from the Cedar River

March – June

y = -0.13Ln(x) + 0.33

R2 = 0.79

0

0.2

0.4

0.6

0 5 10 15 20

Distance to Cedar River

Den

sity

(fis

h/m

2 )

Small creek mouths = highly used Comparison of Deltas and Lake Shore

(South L.Washington and L. Sammamish)

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

00.20.40.60.8

1

Ch

ino

ok

/ m2

Lake shore

Delta

To Avoid Predators, Juvenile Chinook:Avoid areas with little light,

like under docks

Over-water structures cause juveniles to detour to deeper water

Bulk heading and rip rap provide a refuge for

predators, reduce shallow water areas, and prevent

bank sloughing (which supplies fine sediment)

Avoid shorelines without shallow water areas due to bank armoring

Docks affect how fish move along the shoreline

Fish move in schools close to shore (within a few meters)

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 continue to move along the shoreline, close to shore

May-June

direction of travel

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

Microacoustic Tracking at Tennis Club

Ship Canal and Lake Union

Tracking System

RECEIVER

1. “Listening station”

2. Get a fish and a tag

Tracking System

RECEIVER

3. Track your fish

Tracking System

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

Smolt slidesPit Tagging studies

Removing barnacles from the filling culverts

Operation of strobe lights to deter

smolts from entering the filling

culverts

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180 200

Total Daytime Flume Volume (cfs)

Rel

ativ

e G

uid

ance

Eff

icie

ncy

(%

)

May 8

May 9

Fish Passage and Water Flow

Studying the amount of water needed to pass the maximum number of smolts through the flumes

At flows > 80cfs, > 95% of juvenile salmon used the flumes to pass through the Locks

Declining Detection Rates & Surface Water Temperature at the Fremont Bridge

0

50

100

150

200

250

300

350

400

450

11 13 15 17 19 21 23Mean Daily Water Temperature (C)

Nu

mb

er o

f P

IT T

agg

ed F

ish

Det

ecte

d/D

ay

2001

2002

2003

1.Synthesis report of research due end of 2008

2.Microacoustic tracking report due in 2009

Research Wrap-Up

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

Salt water drain adult excluder Installed 6/08

• Biological Opinion: Continuing and new actions at the Locks