Operational and Structual Changes at Two Hydroelectric Dams to Aid in Downstream Juvenile Salmonid Passage Survival on the Mid-Columbia River

Abstract: To meet survival performance standards for out-migrating juvenile salmonids through its two hydroelectric dams (Wanapum and Priest Rapids) that were set by its recently issued Biological Opinion and FERC License, the Public Utility District No. 2 of Grant County, Washington has embarked on a number of structural and operational changes at both of its hydroelectric dams.  These changes have included the design and construction of fish bypasses at each dam; passage behavior and collection efficiency of each bypass has been examined using various juvenile salmonid species; evaluation of smolt survival through the turbines, with an emphasis on optimizing survival; evaluation of powerhouse operations, with an emphasis on the reduction of predation on smolts by piscivorous fish species in the immediate tailraces; new turbine designs (and installation) to increase smolt survival; and also addressing avian predation issues within the reservoirs behind each of the dams.  An overview of these modifications to the dams’ structure and operations, along with their effectiveness to increasing salmonid smolt passage survival through the Priest Rapids Project, will be presented.