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and Evermann and Rutter (1895) made collections in the Upper <br />Colorado River Basin in Colorado and Utah, they did not sample in <br />New Mexico. The first known San Juan River collection in New <br />Mexico was at Aztec in 1934, but no rare fishes were taken. In <br />1936, Colorado squawfish and roundtail chub were collected from <br />the San Juan River (U.S. National Museum [USNM 132091]) but <br />these do not have detailed locality data. In 1959, the presence <br />of Colorado squawfish in the New Mexico portion of the San Juan <br />River was confirmed when two specimens were collected near Rosa <br />in Rio Arriba County (Koster 1960). Between 1934 and 1960, less <br />than 20 collections were made in the San Juan River drainage in <br />New Mexico. <br />In 1961, a pre-impoundment study of Navajo Reservoir (a 1.7 <br />million acre-ft mainstream storage reservoir (U.S. Geological <br />Survey 1985]) was conducted (Olson 1962). That study represented <br />the first major attempt to document the ichthyofauna of the New <br />Mexico portion of the drainage. Notable among the fish captured <br />were Colorado squawfish and roundtail chub. Since the closure of <br />the dam and the accompanying fish eradication program, only one <br />additional Colorado squawfish (500-600 mm TL, taken by an angler <br />in the San Juan River near Bloomfield, H.F. Olson, personal <br />communication) has been reported in New Mexico. <br />The only major survey conducted since 1961, as well as the <br />most extensive to date was that by J.E. Sublette (1977) in the <br />summer of 1976. Sublette and his associates collected at 34 <br />stations on the San Juan River and its tributaries from Pagosa <br />Springs, Colorado to the vicinity of Mexican Hat, Utah. The <br />5