Hydroacoustic Evaluation of Juvenile Salmonid Passage at Lookout Point Dam

We conducted an evaluation of juvenile salmonid downstream passage at Lookout Point dam on the Willamette River in 2010.   The study was conducted for the U.S. Army Corps of Engineers, Portland District (ACOE).  The goal of this study was to provide information on fish passage rates and distribution at the dam to support decisions on long-term measures and operations to enhance dam passage conditions.  The study period was from February 1, 2010 to January 31, 2011.  The objective was to estimate total number, and seasonal, daily, and diel distribution of juvenile salmonid passage through the dam.  We obtained passage data using fixed-location hydroacoustics. This study is still in the data collection and analysis phase.  However, we submitted two in-season reports with preliminary fish passage data to the ACOE; one in August and one in November.  For the August report, we presented raw data of fish passage at the turbines, regulating outlets, and vertical distribution at the dam face for the course of three days in June and 4 days in July.  From June 8 – 10, two juvenile targets passed the turbines and two passed the regulating outlets.  Vertical distribution data show a large number of candidate targets were found in the first 5 meters of the pool and few targets were found at deeper depths.  From July 15 – 18, two juvenile targets passed the turbines.  Vertical distribution data indicated large numbers of targets were found in the upper layer of the water column between the surface and 15 meters deep. For the November report, fish passage data were analyzed for August and September for the turbines and forebay vertical distribution.  These months were chosen because they include a portion of the late summer outmigration of juvenile salmon.  Preliminary estimates of candidate targets show a total of 2,693 juvenile salmon sized fish passed the turbines.  Fish passage began on August 5 and continued throughout August and September.  Run timing peaked on August 20. Vertical distribution data show a large number of fish were found in the upper 10 meters of the pool. Data for the entire study period will be analyzed and presented at the AFS annual Meeting.  Expected results include run timing and passage rates and distribution of juvenile salmonids at the dam.