Northwest Fisheries Science Center

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Document Type: Contract Report
Center: NWFSC
Document ID: 8852
Title: Evaluation of the rehabilitated juvenile salmonid collection and passage system at John Day Dam—1986
Author/Editor: Dean A. Brege, David R. Miller, Richard D. Ledgerwood
Publication Year: 1987
Publisher: National Marine Fisheries Service
Contracting Agency: U.S. Army Corps of Engineers. Portland, Oregon

Improvement of the juvenile salmonid collection and bypass system at John Day Dam on the Columbia River (rkm 347) began in 1984 and continues to date.  The fish collection portion of the system consists of submersible traveling screens (STSs) installed in the gatewell slots to intercept fish passing into the power-generating turbines and guide the fish up into the gatewell slots.  The bypass system consists of 12-inch diameter orifices leading from the gatewells into the bypass gallery and a transportation channel to carry fish from the gallery to a release area approximately 0.25 miles downstream from the dam.  A juvenile fish sampling and handling facility was constructed on the lower portion of the transportation channel for evaluation of fish after they had passed through the system. 

In 1985, personnel of the National Marine Fisheries Service, under contract to the U.S. Army Corps of Engineers, began a series of studies to evaluate the new fish passage system and sampling facilities at John Day Dam.  In 1985, construction was completed in nine of the 16 total turbine units.  The fish guiding efficiencies of the STSs were estimated for all salmonid species and found to be acceptable (>70%) for yearling chinook salmon, Oncorhynchus tshawytscha, and steelhead, Salmo gairdneri, but disturbingly low (21%) for subyearling chinook salmon.  In 1985, orifice passage efficiencies for all juvenile salmonids were greater than 70%.  However, with only nine units completed, orifice head was 5.8 ft, considerably higher than the 3.7 ft expected when all turbine units are connected to the new bypass.  There is a distinct possibility that a decrease in head may result in decreased orifice passage efficiency.  Fish sampling facilities located on the transportation channel were incomplete in 1985, so only preliminary evaluations were possible.