Spillway Deflectors at Bonneville, John Day and McNary Dams on Columbia River, Oregon-Washington and Ice Harbor, Lower Monumental and Little Goose Dams on Snake River, Washington. Hydraulic Model Investigation

摘要

Highly aerated water flowing over the spillways and plunging into the deep stilling basins of dams increases the nitrogen levels of the rivers to a supersaturated condition hazardous to migrating fish. The report presents data and results of hydraulic model studies conducted in development of spillway deflectors for six projects on the lower Snake and Columbia Rivers. The deflectors prevent the plunging action and cause a more skimming-type flow near the surface of stilling basin resulting in reduced nitrogen saturation levels. The models were used to design the deflector geometries and to assist in evaluating their effect on fishway attraction flow near downstream fishway entrances at each project. Prototype measurements indicate that the deflectors have been effective in reducing nitrogen levels at the projects.