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I I I I I I I I I I I I I I I I I I I Vanicek, Kramer, and Franklin (1970) studied the distribution of fishes in the Green River below the dam from 1963 to 1966. Their study showed that several native species, notably Colorado squawfish, were not found above the mouth of the Yampa River, except for the 1-2 miles imme- di ate ly above the Yampa I s mouth (unpub 1 i shed data sheets, Utah Coop. Fish Unit). They indicated that reproduction of all native species was doubtful, in this area, except in 1963 and 1965 (Table 4) when flows were low and temperatures high. Below the mouth of the Yampa River, native fish reproduction, including Colorado squawfish, was similar to before the dam, prompting Vanicek, Kramer, and Franklin (1970) to conclude that the dam had not affected native fishes below that point. Studies conducted from 1969-1971 found no young-of-the-year Colorado squawfish in the Green River from Echo Park to Jensen (Holden and Stalnaker 1975), an indication of failure to reproduce successfully. Seethaler, McAda, and Wydoski (1976) supported this observation in the mid-1970's. Both of these recent studies concentrated in the area below the mouth of the Yampa River. There is little data available for the Green River above the mouth of the Yampa River for the period 1967-1977. Comparison of 1967-77 flow and temperature data for this area, with that of the 1963-66 information (Table 1), would suggest that fish presence would have been similar to what Vanicek, Kramer, and Franklin (1970) found, but that reproduction of native fishes above the mouth of the Yampa probably did not occur because of cold temperatures. Therefore, the 1967-77 portion of Table 4 was left blank and data from the field portion of this study will be used to fill in this gap. -17-