A traveling screen was developed in the Pacific Northwest to divert juvenile Pacific salmon, Oncorhynchus spp., and steelhead trout, Salmo gairdneri, from turbine intakes at Columbia and Snake River Dams. The diverted fish enter gatewells about the intakes and pass through orifices into a central bypass conduit discharging at the tailrace. As envisioned, the system would be capable of diverting up to 90% of the seaward migrants out of the turbine intakes (Ebel et al., 1971), thereby preventing mortalities attributable to passage through the turbines.