Northwest Fisheries Science Center

Display All Information

Document Type: Contract Report
Center: NWFSC
Document ID: 8856
Title: Research at McNary Dam to improve fish guiding efficiency of yearling and subyearling Chinook salmon, 1987
Author/Editor: Dean A. Brege, William T. Norman, George A. Swan, John G. Williams
Publication Year: 1988
Publisher: National Marine Fisheries Service
Contracting Agency: U.S. Army Corps of Engineers. Portland, Oregon

McNary Dam on the Columbia River was completed in 1954 without specific provisions for juvenile fish passage.  All downstream migrants either passed through the turbines or over the spillway.  Research in ensuing years found that turbine passage and migration through reservoirs were detrimental to salmon survival.   Upon development of a means to intercept fish passing through turbines, the U.S. Army Corps of Engineers constructed a juvenile collection system at McNary Dam with submersible traveling screens to collect fish and transport them to a release site below the hydrosystem.

Evaluations of these screens during the spring migration found fish guiding efficiencies (FGE) of over 70% for yearling spring chinook salmon Oncorhynchus tshawytscha, coho salmon O. kisutch, and steelhead O. mykiss.  Studies of subyearling chinook salmon during the summers of 1982 and 1984 yielded FGEs of 33 60%.

In 1987, we continued research at McNary Dam to assess increases in FGE obtained by using a lowered submersible traveling screen, raised operating gate, and trash-rack deflector with both yearling spring and subyearling fall chinook salmon.  From tests in 1987, we arrived at the following conclusions:

  1. The trashrack deflector and lowered STS provided no statistically significant increase in FGE during 1987 tests.
  2. During daylight hours, FGE (under the conditions tested) was higher than during hours of darkness.  This was consistent with findings in 1986. However, in general, only about 15% of the fish pass the project during the day.
  3. Rates of FGE rise and fall with theoretical FGE.  Under normal conditions, with the equipment configurations we tested, average FGEs of 86% for spring chinook salmon, 83% for steelhead, and 25-50% for subyearling chinook salmon are obtainable.
  4. Future FGE and vertical distribution studies should be done in separate turbine units.  Vertical distribution studies would ideally be done with no STSs in adjacent slots.