Downstream Fish Passage at Cushman Hydro Project

Tacoma Power owns and operates the Cushman Hydroelectric Project on the Skokomish River in Northwest Washington. The Project is a nearly 90 year old two dam complex. Cushman Dam No. 2, built in 1930 is the most downstream dam in the Project. Prior to 2015, there were no viable routes of passage for downstream migrating fish from Lake Cushman. In 2010 the Cushman Settlement agreement was finalized and design began on the Floating Surface Collector. Construction is scheduled for completion in April of 2015. The collector is a 250 cfs surface collector. In May and June of 2015 Tacoma will release PIT tagged groups of coho to evaluate System Survival from near the head of the reservoir. Additionally, groups of PIT and acoustically tagged fish will be released approximately 0.25 miles upstream from the collector to assess Fish Capture Efficiency by determining the number of fish that enter the hydraulic zone of influence and are subsequently captured. Behavior of fish entering the hydraulic zone of influence will be characterized in 3-dimentions. Preliminary results of the first season will be related to environmental and operational covariates in this presentation.