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I I I I I I I I I I I I I I I I I I I 66 different macroinvertebrate forms inhabited the Green River between the site of Flaming Gorge Dam and Ouray, Utah (Table 3) (Binns 1965). After closure of the dam, 52 invertebrate taxa were recorded in the same study area between 1962 and 1965 (Table 3)~ Thirty-eight of these taxa were found both above and be 1 ow the conf 1 uence of the Green and Yampa ri vers. Seven taxa were found only above the confl uence and seven taxa were found only below the confluence. Pearson et ale (1968) indicated that the macroinvertebrate community had not been markedly altered below the mouth of Lodore Canyon (65 MBD), though profound changes occurred in its composition near the dam. Little data is available on macroinvertebrate populations in the Green River since 1965. However, a study by Pearson in 1967 on benthic composition at Little Hole indicated considerable changes in macroinver- tebrate populations since 1965 (Table 3). The number of samples taken in 1967 was only 13, therefore, the invertebrate community may not have been adequately sampled. Fishes The Green River, prior to Flaming Gorge Dam, was inhabited with the normal complement of Colorado basin large river fishes and several exo- tics (Bosley 1960; Smith 1960; McDonald and Dotson 1960; Vanicek, Kramer, and Franklin 1970) (Table 4). Most of the pre-impoundment stu- dies (before 1962) were "not as thorough as was the post-impoundment study of Vanicek, Kramer, and Franklin (1970) and other more recent stu- dies (Holden and Stalnaker 1975; Seethaler, McAda, and Wydoski 1976). -13-