Northwest Fisheries Science Center

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Document Type: Contract Report
Center: NWFSC
Document ID: 6527
Title: Effects of turbines operating at two different discharge levels on survival and condition of yearling Chinook salmon at McNary Dam, 2002
Author/Editor: R. F. Absolon, M. B. Eppard, Benjamin P. Sandford, Gordon A. Axel, Eric E. Hockersmith, John W. Ferguson
Publication Year: 2003
Publisher: National Marine Fisheries Service
Contracting Agency: U.S. Army Corps of Engineers. Walla Walla, Washington
Contract Number: W68SBV20655422
Pages: 26
Date: 12/01/2003

This study had two objectives.  The first was to evaluate fish condition after exposure to the gatewell environment at McNary Dam at an operational load above the 1% peak efficiency band (flows of 16,400 ft3/sec) vs. an operational load within the 1% of peak efficiency (11,200 ft3/sec).  The second was to estimate relative survival between fish released at an operating load within 1% peak efficiency (flows of 11,200 ft3/sec) and fish released at the higher load, with flows of 16,400 ft3/sec.

For the first evaluation we used yearling chinook salmon Oncorhynchus tshawytscha obtained from Leavenworth National Fish Hatchery.  Four replicates of 300 fish per group were tagged with passive integrated transponder (PIT) tags, and paired releases of tagged fish were made into gatewell slots 9B and 8B.  Turbine Unit 9 was operated at 16,400 ft3/sec, while Turbine Unit 8 was operated at 11,200 ft3/sec.  No differences in fish condition were found between fish released to the two gatewell environments.

For the second evaluations, we used radiotelemetry tags to evaluate relative survival for run of river yearling Chinook salmon passing through Turbine Unit 9 under operating conditions of 11,200 vs. 16,400 ft3/sec.  Study fish were collected at the McNary Dam juvenile fish facility, held for 24 h, and surgically implanted with both a radio and PIT tag.  Fish were held for an additional 24 h after tagging to monitor post-tagging mortality and tag loss.

Three telemetry receivers and air antenna transects were used to detect radio tagged fish as they migrated downstream.  Transects were located at Irrigon, East Crow Butte, and West Crow Butte, and were approximately 15, 41, and 46 km downstream from McNary Dam, respectively.  PIT tag detections of radio tagged fish at John Day and Bonneville Dams provided additional information.

For each operating condition, we estimated relative survival between fish released through the turbine vs. those released from a site 2 km downstream from the tailrace of McNary Dam.  Point estimates of relative survival were 85.5% (SE = 0.011) at a discharge rate of 16,400 ft3/sec and 87.3% (SE = 0.013) at a rate of 11,200 ft3/sec.  There was no significant difference in survival through Turbine Unit 9 between operational flows of 16,400 vs. 11,200 ft3/sec.