Hydroacoustic Assessment of Downstream Migrating Salmonids at Lower Monumental Dam in Spring 1985




bypass, downstream fish passage, hydroacoustics, intake, juvenile, Lower Monumental Dam, salmon, salmonids, spillway, steelhead, survival, vertical distribution


None supplied. From executive summary: The Bonneville Power Administration and the U.S. Army Corps of Engineers are evaluating bypass methods to increase the survival rate of juvenile salmonids and steelhead migrating downstream through Lower Monumental Dam. For these evaluations it is essential to know the migrants' distribution and timing as they approach and pass the dam, including estimates of the relative proportions utilizing spillway and powerhouse passage routes. In this study migrants passing through the dam were monitored using hydroacoustic techniques. The objectives of the study were to estimate: (1) the effectiveness of the spillway for passing migrants; (2) diel variability in passage rates of migrants through the powerhouse and spillway; (3) the daily and cumulative run timing of migrant passage; (4) the proportions of migrants that passed through each turbine intake and spill bay; (5) the vertical distributions of migrants approaching the powerhouse and spillway. The study was conducted from April 22 to May 31, 1985.

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