Assessing compliance with fish survival standards: a case study at Rock Island Dam, Washington

Safe fish passage through hydroprojects is of paramount importance in the Pacific Northwest of the United States where anadromous runs of salmon smolts pass through as many as nine dams on the Columbia River on their way to the ocean. Minimum survival standards through the dams or hydroprojects (i.e., reservoir and dam) have been established by the 2008 Federal Columbia River Power System (FCRPS) Biological Opinion or by Habitat Conservation Plans (HCPs) in order to protect salmon stocks. These federal requirements have prompted the need to conduct scientifically and statistically rigorous and precise smolt survival studies at federally and publicly operated hydroprojects throughout the Snake-Columbia River Basin. Successful studies have been the cooperative results of regulators, hydro managers, fish biologists, engineers, and biometricians working together to conduct these high value investigations. Rock Island Dam, Washington, is used as a case study where a total of 17 release-recapture studies were conducted over a nine-year period on three salmonid species to assess compliance with HCP survival standards.

► Assessed compliance of a public utility managing a hydro project to meet survival standards for salmonid smolts.
► Habitat Conservation Plan (HCP) requires project passage survival (tailrace to tailrace) equal to or greater than 0.93.
► All 17 trials over 9 years met precision requirements with SEs for estimates of project passage survival less than 0.025.
► Compliance was met with three different fish stocks and at two different operating levels.
► Success was the result of the cooperation between hydro managers, regulatory agencies, and the scientific community.