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The need to provide passage and protective screens at irrigation diversions has always been a necessary part of the Columbia River Basin Fish and Wildlife Program (NPPC 1984, 1987, 1994). From 1985 through 1990, fish protection facilities in large irrigation diversions throughout the Columbia Basin, especially in the Yakima Basin, were updated. After 1990, fish protection efforts turned to installation of new facilities on unscreened diversions and to repair and upgrade of older facilities. The screening program also includes funds to monitor and evaluate the facilities. The screen evaluations indicate they are an effective means for protecting juvenile fish larger than 40 mm in length. As state and federal agencies change screening criteria to protect smaller fish (e.g., bull trout fry), the physical barrier may not always be effective. Screen mesh small enough to protect fish may be vulnerable to frequent plugging. Gap tolerances on side and bottom seals may be difficult to install and maintain. Physical barrier screens can be enhanced with behavioral barriers that cause fish to avoid a hazard. Behavioral barriers may consist of sound generator, strobe lights, bubble curtains, or electrical barriers. State of Oregon House Bill 3112 states that "Standards and criteria shall address the overall level of protection necessary at a given water diversion and shall not favor one technology or technique over another." Additionally, it goes on to say, "Screening device means a fish screen or behavior barrier." Other Northwest states, in particular Washington, have taken a comprehensive program to install barriers at all unscreened diversions by 1999. Protecting all fish at all water withdrawals will probably require both physical and behavioral barriers. The purpose of this study is to evaluate the effectiveness of using an underwater sound-generator as a behavioral barrier for possible use at fish diversion facilities. This study did not include engineering and economic evaluations needed to produce, deploy or install sound equipment at existing or planned fish screening facilities. The focus of this study is to determine if fish, specifically juvenile salmonids, can be guided by sound

Evaluation of Low and High Frequency Sound for Enhancing Fish Screening Facilities to Protect Outmigrating Salmonids.