1. Eightmile Creek Barrier Assessment

2. Agenda Intro Fish Size and Stream Flows Data Collection and Modeling
Passage Analysis
Conceptual Designs

3. Objective Fish Passage Analysis Lower 2 miles of Eightmile Creek
Species Steelhead and Bull Trout
October 6, 2009 Field Reconn
Sites: RM 1.87 and RM 0.72

4. RM 1.87
RM 0.72

5. RM 1.87 Falls 1

6. RM 1.87 Falls 2

11. Falls RM 0.72

14. Fish Size, Migration Timing
WDFW data of Steelhead collected at Wells Dam
USGS tagging studies from the Chewauk River
Observations by USFS Biologists of Bull Trout in Eightmile Creek
Bull Trout and Steelhead sizes used for the Mill Creek, Walla Walla River - Fish Passage Assessment Report (Powers, 2009).

15. Stream Flows Stream Gage Measured Flows of 16, 32, 100 and 141 cfs
Regression model developed by Orsborn (2002), for the Methow-Chelan basins.
Eightmile Creek basin area 46.6 square miles, mean annual precipitation is 35 in/yr

16. Regression Model Two Year Peak flow = 414 cfs
Mean annual flow = 42 cfs
Two Year Peak flow = 414 cfs
100 Year Peak Flow = 1665 cfs
2 Year 7 Day low flow = 7.4 cfs

18. Fish Size (inches) Species Timing in Eightmile Cr Stream Flows
10%/50%/90%
(cfs)
Primary source
Range
10%
50%
90%
Steel-head
32 – 24 24 27 30
February - May
93/43/18
WDFW
Bull trout
5 -26 7 9 17
June - October
108/44/18
USGS

19. Data Collection Topographic Survey with total station
Water levels at higher flows tied to survey vertical datum and station
Photos
Random velocity measurments
Observations of passage routes, turbulence

22. RM 1.87 Data Collection

23. RM 1.87 measured ground and water surface profiles at 16, 100 and 141 cfs.

24. HEC RAS Model at 16 cfs

26. HEC RAS Model at 141 cfs

27. EDF
EDF = 16 * Q * H/V
Q = flow (cfs), H = drop (ft), V = Pool Volume (cu ft)
Unit: ft lbs/sec/cu ft water

30. Energy Dissipation Factor (EDF)
Flow (cfs)
Energy Dissipation Factor (EDF)
RM 1.87
RM 0.72
Falls 1
Falls 2 18 4 6 44 7 10
108 16

31. Conceptual Model of a Falls

32. Example of Leaping Angle

33. Fish Passage Calculations
Fish passage success is calculated by comparing fish leaping and/or swimming abilities to the geometry and hydraulics of the falls.
Threshold gradient for leaping versus swimming analysis is 35%.
The passage index for a species is a sum of the individual calculations for each combination of fish size, stream flow and passability

34. RM 1.87 Falls 1
16 cfs
32 cfs
141 cfs
RM 1.87 Falls 2

35. Passage Analysis RM 1.87

36. Falls RM cfs

37. Passage Analysis RM 0.72 Bull Trout (2% Passage) Stream Flow (cfs) 18
Fish Size (inches)
Stream Flow (cfs) 18 44
108 7
Barrier - Height 9 17
Passable
Barrier – Height/EDF
Steelhead (86% Passage) 24
Barrier- EDF 27 30

38. Calculated Versus Observed Passage
Sept 22, 2009 USFS ,conducted a bull trout redd survey from the bridge at FS Road 5130 to the mouth. Three redds were located downstream of the bridge (Humling)…………fish size 15 to 18”?
During survey of the falls at 16 cfs, a small trout (6 to 8”) was observed leaping at Falls 2 but not passing (Powers)
Recently a 11 inch Bull Trout was found upstream at RM 6.2 (Gene)

39. Conceptual Designs
Falls RM 0.72 – Natural Falls, Log Spanning Creek, Fish Less than 15” can’t pass.
RM reach overall slope 9.4 percent
Falls 1: Height, Distance and EDF Barrier – Break into two drops
Falls 2: EDF and Velocity Barrier – Widen Channel 15 to 20 feet
Overall Correction 10% Step/Pool Channel with large boulders, 2 to 3 foot drops over 20 to 30 foot spacings