1. Study Update Tailrace Slough Use by Anadromous Salmonids

2. Goals and Objectives
Identify what anadromous salmonids use the tailrace slough by:
Life Stage (Juvenile, migrating and spawning adults)
Timing
Type of use

3. Study Area
The tailrace slough immediately downstream of the Project tailrace terminus to its confluence with the Cowlitz River
Given that the configuration of the tailrace changes frequently, the area surveyed was within the bankfull channel at the time of the study

4. Study Area Right Channel Left Channel Main Channel Right ChannelX
Right Channel X X X
Right Channel
Tailrace Mouth X
Main Channel
Above Split
Left Channel
Left Channel
Main Channel
X = Study Sites

5. Methods
30 m of every 160 m is snorkeled seasonally for 1 year assessing:
Fish species presence
Life Stage and Approximate Length
Habitat Characteristics
Depths
Velocities
Substrate Composition
Habitat Types

6. Survey Issues
A Spring 2006 survey could not be conducted due to a period of extended high water and extreme turbidity
A fall/winter survey was scheduled for Dec. 10th. High flows and long term turbid water associated with the November, 2006 flood precluded biologists from conducting a survey until January, 2007.
Comprehensive documentation of adult use in the tailrace slough from the Anadromous Spawning Surveys during the period from August to January ( ) was utilized for anadromous fish presence information during the fall/winter period.

7. Survey Dates and Associated Flows
July 27, 2006 (Finished August 2nd, 2006)
Cowlitz River – 925 cfs Tailrace – 94 cfs
(Snorkeled)
January 15, 2007
Cowlitz River – 1370 cfs Tailrace 58 cfs
(Electrofished)
April 26, 2007
Cowlitz River – 1430 cfs Tailrace 44 cfs
June 19, 2007
Cowlitz River – 2030 cfs Tailrace 110 cfs

8. Results from the July, 2006 Survey
A total of five 30 m sites were surveyed
618 coho juveniles were observed in the left side channel
4 Chinook juveniles were observed in the left side channel
50 coho juveniles were observed in the right side channel
200 coho were observed in the channel prior to the split
Other species documented include:
rainbow trout
whitefish
sucker

9. 4 Table 3-1 July, 2006 – Habitat and Fish Observation Information
Habitat Percentages
Depth Range (ft)
Riffle
Run
Glide
Pool
Substrate
Velocity Range (Fps)
Number of Coho Juveniles Observed
Number of Chinook Juveniles Observed
Left Side Channel Study Sites 10 16 74
Cobble/ Gravel
0.35/1/35
0.09/1.39
606 4
Right Side Channel Study Sites
100
Sand
0.85/1.4
0.3/1.01 81
Main Channel Above Split Study Sites
Sand/ Gravel
1.2/3.75
0.1/1.27
472

10. Results from the January, 2007 Survey
The same five 30 m sites were surveyed
Secondary habitat types changed as a result of flooding in November, 2006.
No anadromous species were observed in any of the study sites.
Other species documented include:
rainbow trout
whitefish
sucker

11. Table 3-2 January, 2007 – Habitat and Fish Observation Information
Habitat Percentages
Riffle
Run
Glide
Pool
Substrate
Depth Range (ft)
Velocity Range (Fps)
Number of Coho Juveniles Observed
Left Side Channel Study Sites 67 33
Sand/ Cobble
0.9/1.8
0.01/0.65
Right Side Channel Study Sites 50
Gravel/ Cobble
0.85/1.65
1.18/2.57
Main Channel Above Split Study Sites
100
0.65/3.0
0.97/1.73

12. Results from the April, 2007 Survey
The same five 30 m sites were surveyed
March high water resulted in secondary habitat types being altered at the study sites
301 coho juveniles were observed in the left side channel
1 Chinook juvenile was observed in the right side channel
200 coho juveniles were observed in the main channel before the split
Other species documented include:
rainbow trout
whitefish
sucker

13. 1 Table 3-3 April, 2007 – Habitat and Fish Observation Information
Habitat Percentages
Depth Range (ft)
Riffle
Run
Glide
Pool
Substrate
Velocity Range (Fps)
Number of Coho Juveniles Observed
Number of Chinook Juveniles Observed
Left Side Channel Study Sites 12 88
Gravel/ Cobble
0.2/1.0
0.0/2.33
301
Right Side Channel Study Sites
100
Gravel
0.6/1.4
2.17/3.32 1
Main Channel Above Split Study Sites
Sand/ Gravel
0.3/3.6
0.12/1.6
200

14. Results from the June, 2007 Survey
The same five 30 m study sites were surveyed
High water related to runoff altered secondary habitat types between the April and June surveys
Approximately 1400 coho juveniles were observed in the left side channel
No fish were observed in the right channel
25 coho juveniles were observed in the main channel above the split
Other species documented include:
rainbow trout
whitefish
sucker

15. Anadromous Fish Presence
No Anadromous adults were observed during the surveys
Juvenile presence varied by season and channel
Coho presence dominated the surveys which correlates well with anadromous spawning survey numbers seen in the tailrace slough

17. Habitat Conditions
The left side channel has a higher gradient, varying substrate composition and much higher habitat diversity than the right channel
The right channel consists of uniform habitat with very little suitable habitat for anadromous juveniles or adults
Gravel was transported into the main channel above the split as a result of the November, 2006 and March, 2007 high water events

18. Left Side Channel

19. Right Side Channel

20. Main Channel Above Split

21. Conclusions
The tailrace slough area is a dynamic complex that can go through dramatic hydrologic and habitat alterations as a result of high flows from the Cowlitz River
Throughout these alterations, during ENW studies, the left side channel maintained its high level of spawning and rearing habitat. A majority of coho juveniles and all coho spawners were observed in the left side channel
All gravel and wood that is routed into the area is a product of transport down the Cowlitz River. No wood or gravel is sent down the tailrace into the tailrace slough area.

22. Conclusions No coho were observed during the January, 2007 survey
Emergence typically occurs in April with most coho out-migrating as year 1+ (over wintering) juveniles. Low flows in the late summer months likely push a majority of the juvenile coho into the mainstem Cowlitz River or other perennial side channels downstream for further rearing. This movement of juveniles during the late summer combined with the November, 2006 flood likely explains the lack of coho observations during the January survey.
The largest number of coho juveniles were observed during the June, 2007 survey, (n=1400). Rearing areas in the left side channel are still wetted at this time and there is a large amount of slow moving pocket water still available.
The lack of Chinook and Steelhead in the area is to some degree attributable to the following:
Lower numbers of adult Chinook and steelhead spawners released above mainstem Cowlitz River Dams
Fewer fish associated with an abundance of suitable spawning and rearing habitat in the upper Cowlitz River lowers the likelihood of observations in the tailrace slough
Chinook spawn timing, (late July – September) is consistent with periods of low flow in the tailrace slough, likely precluding spawners from utilizing a majority of the quality habitat

23. Study Report Schedule
Input Please??