Yakima River Basin Phase II Fish Screen Evaluations, 2001.

In the summer and fall of 2001 the Pacific Northwest National Laboratory (PNNL) evaluated 23 Phase II fish screen sites in the Yakima River Basin as part of a multi-year study for the Bonneville Power Administration (BPA) on the effectiveness of fish screening devices. Data were collected to determine if velocities in front of the screens and in the bypasses met current National Marine Fisheries Service (NMFS) criteria to promote safe and timely fish passage and whether bypass outfall conditions allowed fish to safely return to the river. Based on our studies in 2001, we concluded that: in general, water velocity conditions at the screen sites met fish passage criteria set forth by the NMFS; most facilities efficiently protected juvenile fish from entrainment, impingement, or migration delay; automated cleaning brushes generally functioned properly; chains and other moving parts were well greased and operative; and removal of sediment build-up and accumulated leafy and woody debris are areas that continue to improve. Continued periodic screen evaluations will increase the effectiveness of screen operation and maintenance practices by confirming the effectiveness (or ineffectiveness) of screen operating procedures at individual sites. Where procedures are being followed and problems still occur, evaluation results can be used to suggest means to better protect fish at screening facilities. There has been a progressive improvement in the maintenance and effectiveness of fish screen facilities in the Yakima River Basin during the last several years, in part, as a result of regular screen evaluations and the rapid feedback of information necessary to improve operations and design of these important fish protection devices. Continued periodic screen evaluations will increase the effectiveness of screen operation and maintenance practices by confirming the effectiveness (or ineffectiveness) of screen operating procedures at individual sites. Where procedures are being followed and problems still occur, evaluation results can be used to suggest means to better protect fish at screening facilities. There has been a progressive improvement in the maintenance and effectiveness of fish screen facilities in the Yakima River Basin during the last several years, in part, as a result of regular screen evaluations and the rapid feedback of information necessary to improve operations and design of these important fish protection devices