A Fisheries Evaluation of the Westside Ditch and Town Canal Fish Screening Facilities, Spring 1990.

The Pacific Northwest Laboratory (PNL) evaluated the effectiveness of new fish screening facilities in the Westside Ditch and Town Canal, near Ellensburg, in south-central Washington State. At the Town Canal, we estimated that 0.3% of steelhead Oncorhynchus mykiss smolts released during tests were significantly descaled. The time required for 50% of the fish in the two steelhead test groups to exit from the Town Screens forebay ranged from 12 h to >85 h. Integrity tests at the Town Screens indicated that none of the rainbow trout fry released in front of the rotary drum screens passed through the screens, although 8.5% of the native zero-age chinook salmon fry diverted from the river into the screening facility were lost through the screens. At the Westside Screens, 16.8% of native zero-age chinook salmon fry passed through the screens. Most of the chinook salmon lost through the screens were small, <36 mm long. The methods used in 1990 were first used at the Sunnyside Screens in 1985. These methods were used again in subsequent years in tests at the Richland, Toppenish/Satus, Wapato, and Toppenish Creek screens. The methods used from 1985 through 1989 have been reviewed by the Washington State Department of Fisheries,more » US Fish and Wildlife Service, National Marine Fisheries Service, Northwest Power Planning Council, and Yakima Indian Nation. 14 refs., 12 figs., 7 tabs.« less