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documenting their presence in New Mexico. One year later, three young Colorado squawfish were taken in Utah, at Mexican Hat, by R. R. Miller et al. (Sigler and Miller 1963). t Post 1960 Studies Navajo Reservoir Pre-impoundment Two pre-impoundment fish studies were conducted in the area to be inundated by Navajo Reservoir. A team of researchers from the Department of Anthropology at Utah University was funded by the U.S. Bureau of Reclamation (USBR) to perform ecological studies of the flora and fauna of Navajo Reservoir basin in Colorado and New Mexico. From 28 June to 25 July 1960, data were gathered on the plant community and related fauna of Navajo Reservoir basin for the express purpose of "recording conditions existing in the immediate area before a part of it is submerged by water of the reservoir." The "related fauna" included six fish collections (which contained a total of five roundtail chub) from the Piedra and Los Pinos rivers, Sambrito Creek, and the upstream reaches of the San Juan River (Dean 1961). A more thorough ichthyofaunal survey of the area to be impacted by Navajo Dam and Reservoir was conducted in 1961 by the New Mexico Department of Game and Fish (NMGF)(Olson 1962, Koster 1963). This study was the first major attempt to document the ichthyofauna of the upper portion of the drainage and was the last accomplished before the closure of Navajo Dam. Notable among the fish captured were roundtail chub and Colorado squawfish. Since the closure of Navajo Dam and the accompanying fish eradication program, only one additional Colorado squawfish (taken by an angler in the San Juan River near Bloomfield, H. F. Olson, pers. comm.) has been reported in New Mexico. Navajo Reservoir Post-impoundment Since 1961, there have been several biological surveys in the San Juan River drainage, most in Colorado or New Mexico. The NMGF monitored ichthyofaunal changes in and below Navajo Reservoir through 1968 (Olson 1963, 1967, 1968, Olson and McNall 1965, Graves and Haines 1968, 1969). C. B. Stalnaker and D. Campbell collected fish, including 29 roundtail chub, from the mouth of the Los Pinos River in July 1967 (Fort Collins/ Biological Survey [FC/BS] 2690 to 2700, 2702 to 2719). From 1972 to 1974, an ichthyofaunal survey was conducted in the Rio Blanco and Navajo River (Colorado and New Mexico) as part of a larger study of the San Juan-Chama diversion project (Anonymous 1976). Jensen (1975) reported on the aquatic biota at 10 sites sampled in Navajo Wash and the Mancos and San Juan rivers in Colorado and New Mexico in 1974; Smith (1976) documented the fish, invertebrates, and physico-chemical parameters at sites in the Animas, La Plata, and Mancos river systems (Colorado and New 4