Eightmile Creek Barrier Assessment

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

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

RM 1.87 RM 0.72

RM 1.87 Falls 1

RM 1.87 Falls 2

Falls RM 0.72

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).

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

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

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

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

RM 1.87 Data Collection

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

HEC RAS Model at 16 cfs

HEC RAS Model at 141 cfs

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

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

Conceptual Model of a Falls

Example of Leaping Angle

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

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

Passage Analysis RM 1.87

Falls RM 0.72 141 cfs

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

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)

Conceptual Designs Falls RM 0.72 – Natural Falls, Log Spanning Creek, Fish Less than 15” can’t pass. RM 1.87 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