Great Lakes Environmental Center researchers investigated turbine passage and possible mortality of fish at a hydroelectric power project and proposed fish diversion strategies for fish protection. Mitigative techniques were evaluated for their effectiveness to prevent or minimize turbine passage and mortality. A study was conducted in northeastern Michigan from May of 1992 through April of 1993 to determine the extent of turbine passage. That information was used to develop tentative fish diversion and exclusion strategies for the overall operational plan for the facility. During the spring of 1994 and 1995, we conducted pilot fish diversion demonstration studies using behavioral fish deterrent systems. Underwater strobe lighting and fine bubble air curtain technologies were used to deter fish away from turbine forebay areas. Strobe lighting, air curtain and a combination of the two treatments were alternated with no treatment (control) to determine the effectiveness of each treatment. We compared the data for significant differences (p0.05) using non-parametric (Wilcoxon Signed Rank Test) and parametric (ANOVA) procedures and also determined effectiveness indices and percent reduction in turbine passage with each treatment. Our data indicated that strobe lighting and a combination of fine air bubble curtain and strobe lighting were successful as fish diversion/exclusion techniques (77 and 80 percent reductions, respectively). Air bubble curtains alone did not deter significant numbers of fish. These techniques significantly reduced turbine passage and consequently will help reduce potential mitigative costs for fish losses.
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