Hydroacoustic evaluation of fish passage through a prototype surface bypass collector at Rocky Reach Dam
bypass, fish passage, prototype, surface bypass, salmon, steelhead, Columbia River, hydroelectric, hydroelectric dams, dams, juvenile, salmonids, entrance, horizontal, horizontal distribution, vertical distribution
Innivations in Fish Passage Technolgy
American Fisheries Society
Salmon and steelhead runs on the Columbia River and its tributaries have been indecline due to several factors, including the operation of hydro-electric dams. In 1995, aprototype surface collector (PSC) was constructed at Rocky Reach Dam to bypass fish aroundthe turbine units. The PSC uses considerably less flow than a turbine unit and passes fish withminimal stress. Juvenile salmonids were monitored using hydroacoustic methods, whichpermitted efficient, nonobtrusive sampling of the fish. Sapling was conducted at the site in 1995and 1996 to estimate the proportion of juvenile fish detected in front of the PSC using acombination f single-beam and split-beam hydroacoustic techniques. For the two years ofoperation, the proportion of fish travelling toward the PSC entrance as a function of depth variedfrom 76% in 1995 to 70% in 1996. The horizontal distribution of fish passage across the damshowed that most fish were detected in the vicinity of the PSC for both study years. The verticaldistribution of the fish detected in front of the PSC was normally distributed throughout the watercolumn. In summary, hydroacoustic studies in 1995 and 1996 showed that the PSC providedefficient bypass route for downstream migrating juvenile salmonids at Rocky Reach Dam.