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The Problem
The National Marine Fisheries Services Biological Opinion on the Columbia River salmon listed under the Endangered Species Act sets guidelines for salmon recovery. Many of the guidelines address salmon passage issues at hydroelectric dams operated by the U.S. Army Corps of Engineers (COE), because fish passing through turbines experience higher mortality than those that go over the spillway. To meet these guidelines, the COE has undertaken a series of studies to improve downstream passage conditions for juvenile salmonids. There are currently no structural methods employed to divert juvenile fish from turbine entrainment at The Dalles Dam, because the ice-trash sluiceway and spillway have been more effective at this dam than at most others. However, even during periods of 30 to 40% spill, turbine entrainment is often approximately 15% during the night, indicating some type of additional measure is warranted. The most recent such measure has been installation and testing of "J"-design turbine intake occlusion structures. These were used in an effort to reduce turbine entrainment by blocking off the upper half of the turbine intakes. Objectives The objective of this study is to determine the approach pattern and passage locations of juvenile salmonids to assist in planning decisions relative to a behavioral guidance structure at The Dalles Dam. This will be accomplished by comparing estimates of fish, spill and sluiceway passage efficiencies of fish with different approach patterns. The approach patterns will be determined using three in-river telemetry arrays. Methodology This study is based on radio-tagged juvenile chinook salmon (Oncorhynchus tshawytscha) and steelhead (O. mykiss) released approximately 50 km upstream. A series of underwater and aerial antennas connected to data logging telemetry receiving systems will be used to detect the fish as they approach and pass the dam, enabling the proportions of fish passing each route (i.e., turbines, sluiceway, or spillway) to be determined. In FY2002 approximately 3500 yearling chinook salmon, 3500 juvenile steelhead and 7000 subyearling chinook salmon were released upstream this and other studies conducted by the USGS in the vicinity. The overall fish passage efficiency (the proportion of fish passing
Highlights and Key Findings Assessments of juvenile salmonid passage studies at The Dalles Dam were conducted in 1999, 2000, 2001 and 2002. Data from 2000, testing 40% spill and the juvenile pattern, indicated that juvenile chinook salmon had a fish passage efficiency (FPE) of 84.7% and a juvenile steelhead FPE of 91.2%. The spill passage efficiencies (SPE) were 79.3 and 85.4%, respectively. Sluiceway passage efficiencies (SLPE) were 5.5 and 5.8%. The FPE, SPE, and SLPE estimates from subyearling chinook salmon during 2000 were 88, 77, and 11%, respectively. Data from 2001, tests of J-design intake occlusion plates, were inconclusive due to variation from study protocols. Results of the 2002 study testing the occlusion plates indicated reductions in turbine passage of yearling chinook salmon and subyearling chinook salmon, but not wild steelhead. Data collected during 40% spill in 2000 were typically more similar to those collected during 64% than at 30% spill in 1999 (Table 1). Fish passage efficiencies of yearling chinook salmon during 40% spill were intermediate to those during 30% and 64% spill, but those of juvenile steelhead were similar during all spill percentages tested. Spill passage efficiencies during 40% spill were very similar to those during 64% spill and SLPE was lower during 40% spill than during the other treatments. Data from 2002 indicated that overall FPE and SPE were similar to previous years during like spill conditions (Table 1). Data from underwater antennas at the powerhouse indicated turbine passage of yearling and subyearling chinook salmon was significantly lower during the occluded treatment level.
Where Are We Headed In 2003 The approach patterns and subsequent passage locations of juvenile salmonids will be determined in 2003 to provide data regional fishery managers can use to assess the utility of the use of a behavioral guidance structure and The Dalles Dam in the future. Detected fish will also be used in USGS studies of salmon survival. Project Contact John Beeman Email: john_beeman@usgs.gov Publications | ||||
