Large numbers of shad also impede salmon passage through adult fishways. Fish Counts: The majority of adult salmon are counted at dams by real-time human observations, which are prone to errors. The current objective of the Corps of Engineers is to count only 80% of the adult run, with the majority of counts occurring during daytime hours. Adult fish returning from the ocean to their spawning grounds pass the dams through fish ladders. Snake River chinook and steelhead go through 8 dams (Bonneville to Lower Granite) and Upper Columbia chinook and steelhead go through 4 federal dams (Bonneville to McNary). Upper Columbia stocks also go through public utility-owned dams above McNary.
Fremont Weir Adult Fish Passage Modification Project In , Reclamation and the California Department of Water Resources (DWR) began the Fremont Weir Adult Fish Passage Modification Project to improve adult fish passage at the Fremont Weir and along the Tule Canal in the Yolo Bypass. Photo Courtesy of Dennis Schwartz US Army Corps of Engineers Photo of The Dalles Dam Spillwall March Fish Passage Plan Corps of Engineers Projects.
More information about adult fish passage and migration is provided in the Adult Salmon Passage recommendation and in the new technical recommendation Predation. The diversion dam is just three miles downstream from the Howard Hanson Dam, and has already been improved with a trap for adult fish passage. Fish captured in the trap will be trucked above the.