Project: Summary of Adult Steelhead Passage and Conversion in the Federal Columbia River Power System
Client: USACE – Walla Walla District
Location: Lower Columbia and Snake RiversColumbia and Snake River summer steelhead often have complex, multi-stage pre-spawn homing migrations followed by rapid post-spawn ‘kelt’ migrations. Their extended freshwater migration and residency periods, as well as use of habitats outside of their direct migration route, create a variety of concerns for management of the Federal Columbia River Power System (FCRPS) including potential need for surface-flow (i.e., non-turbine) downstream passage routes at dams during traditional non-spill periods. This is especially an issue in winter and spring when many adult steelhead are present in the FCRPS and can be overwintering (holding by pre-spawn fish), migrating upstream (post-overwintering pre-spawn fish), or moving downstream (post-spawn kelts and pre-spawn adults that ‘overshoot’ their natal tributary).
This study summarized available data on these behaviors and evaluated their effects on survival through the FCRPS. We summarized available data and identified remaining sources of uncertainty associated with year-round adult steelhead passage and survival through the FCRPS including: (1) timing, location, duration, and survival during overwintering; (2) dam, reservoir, and tributary passage behaviors and timing; (3) downstream fallback locations, frequency, timing, routes, and associated survival for both pre-spawn adults and post-spawn kelts; (4) location, timing, and frequency of natal tributary ‘overshoot’ and associated permanent straying; and (5) estimation of dam-to-dam and multi-dam reach conversion rates.
Project was conducted with University of Idaho and Blue Leaf Environmental and required close coordination and collaboration with the Corps and NOAA Fisheries, as well as multiple Federal, State, and Tribal stakeholders.