Laboratory Studies of Screens for Diverting Juvenile Salmon and Trout from Turbine Intakes

Abstract

Abstract Fish-guiding screens of different porosities were tested with juvenile spring chinook salmon (Oncorhynchus tshawytscha) in a laboratory model that simulated a turbine intake and gatewell (a vertical shaft in a dam that extends from the forebay deck to the ceiling of the intake). The study was part of a program to develop methods for preventing mortality of juvenile salmon and steelhead trout (Salmo gairdneri) in Kaplan turbines of low-head dams on the Columbia and Snake Rivers. If large numbers of juvenile fish could be guided into gatewells, a method of safely bypassing them around turbines might be devised. Three types of screens (wood, and single and double layers of spiral-weave conveyor belt) were attached to the intake ceiling at an angle of 45° to the flow; their lengths were adjusted to intercept one-third or two-thirds of the total flow into the intake. The screen with the greatest porosity (constructed of a single layer of belting) gave the highest guiding efficiency; 87% of the test fi...