SALMONID SMOLT SURVIVAL RELATIVE TO TURBINE EFFICIENCY AND ENTRAINMENT DEPTH IN HYDROELECTRIC POWER GENERATION

At the Lower Granite Dam on the Snake River near Almota, WA, where intake guidance screens divert salmon upward into vertical bulkhead slots in the dam, salmonid smolt survival was examined relative to turbine efficiency and entrainment depth. A tag recapture technique was employed. No significant correlation was found between the highest fish survival and the peak turbine operating efficiency, as highest survival occurred at the lowest turbine operating efficiency. Entrainment depth did not appear to affect fish survival markedly, and the extended-length guidance screens did not reduce survival. The injury rate generally paralleled the survival trend, although the data suggested that deeper entrained fish in turbines equipped with extended-length screens suffered greater shear- and pressure-related injuries.