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EXECUTIVE SUMMARY <br />Non-native fish removal was conducted in the Green River, Utah and Colorado, <br />downstream of Flaming Gorge Dam in Browns Park, Lodore and Whirlpool canyons, and Island- <br />Rainbow Park. Non-native fish abundance and fish community responses in the reach were <br />evaluated relative to non-native fish removal as well to different flow and temperature regimes <br />that are influenced by Flaming Gorge Dam. We place emphasis on comparisons between the <br />1994 to 1996, 2002 to 2004, and 2005 to 2006 periods. We also make recommendations for <br />attempting to understand non-native predator abundance and fish community change in relation <br />to multiple potential driving variables including fish removal and Flaming Gorge flow and <br />temperature regimes. <br />Four major dam-related events affected physical habitat and the fish community of the <br />upper Green River: dam installation in 1962, penstock modification in 1978, flow re-regulation <br />beginning in 1992, and higher peak flows, and lower base flows, and drought events since 2000. <br />The impacts of construction and operation of Flaming Gorge Dam on physical habitat in the <br />highly regulated reach of the Green River from the dam downstream to the Yampa River and in <br />Whirlpool Canyon downstream of the Yampa River included lowering peak flows, increasing <br />base flows, lowering summer water temperatures, and reducing sediment transport and turbidity. <br />Regulation effects were partially remediated by thermal modifications implemented in 1978, <br />discharge re-regulation in 1992, and 2002 to 2006 drought-period changes to base flow levels <br />and patterns. Relatively higher releases in 1997, 1999, 2005, and 2006, and drought-induced <br />high water temperatures created conditions that more closely resembled pre-dam conditions. <br />Peak flows were lower in most other years and at the relatively low power plant capacity <br />including those from 2002 to 2004. Flows in the 2002 to 2006 study period also had a more <br />stable, albeit slightly higher than historical, summer-winter base flow pattern because power <br />iv <br />