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• <br /> <br />ABSTRACT <br />Distribution of Macroinvertebrates in the Green River <br />Below Flaming Gorge Dam, 1963-1965 <br />by <br />William D. Pearson, Master of Science <br />Utah State University, 1967 <br />Major Professor: Dr. Robert H. Kramer <br />Department: Wildlife Resources <br />This study was undertaken to determine the effects of rotenone <br />applied during a fish control operation in September 1962 and the in- <br />stallation of Flaming Gorge Dam in November 1962 upon the distribution <br />of invertebrates in the Green River. Since these two events, the <br />river has changed from a warm, turbid stream to a cold, clear trout.., <br />stream for about 45 miles below the dam. Totals of 234 bottom <br />11 <br />samples and 394 drift samples were collected between the dam and <br />Ouray, Utah (166 miles below the dam). The species composition of <br />the fauna above Carr Ranch was much simpler during 1964-65 4han the <br />reported pre-impoundment composition. Below Carr Ranch the species <br />composition of the invertebrate fauna has changed little. Bottom- <br />fauna densities were highest near the dam (max. 6347/ft.2) and de- <br />creased with increasing distance below the dam. Population densi- <br />ties below Carr Ranch (42.7 miles below the dam) appeared to be <br />similar to reported pre-impoundment densities. Drift rates of Baetis <br />nymphs and Simuliidae larvae were highest near the dam. Illumination, <br />population density.of other organisms, and water temperature had