Hydraulic evaluation of fish attraction potential at Merwin Dam fish collection facilities

This paper discussed a 1:24 scale physical model constructed to optimize a proposed fish trap entrance for a hydroelectric project located on the Lewis River in Washington state. The fish trap entrance will be placed at the Merwin dam, which is located at the furthest point downstream of the main project. The new adult fish passage facilities will collect, sort, and transport adult fish migrating upstream from the ocean. The physical model was used to confirm the preliminary entrance locations as well as to evaluate attraction flows and optimize entrance weir designs. A pump station intake arrangement was also designed to supply fishway attraction flow. It was concluded that the model will also be used to document tailrace flow patterns in order to assist with future studies of fish behavior and dams. 5 figs.