Louver Efficiency in Deflecting Downstream Migrant Steelhead Maxwell Ditch, Umatilla River, Oregon

An efficiency of 98 percent was achieved in deflecting young, downstream migrant steelhead trout by employing vertical louvers in Maxwell Ditch, Umatilla River, OR. The depth of the canal precluded an adequate test of horizontal louvers. The principles employed in applying louvers for deflecting fish are explained. The design of the facility in which vertical and horizontal louvers were placed is described. Results are given for tests with several approach and bypass velocities and different louver slat spacings. Discussed are the effectiveness of the louvers in deflecting immature steelhead, fish other than immature steelhead, head loss created by the louver installation, and the deficiencies present at Maxwell Ditch for determining the efficiency of horizontal louvers.