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Osmundson (2000) believed that river water temperatures could be used to predict upstream distribution for adult Colorado pikeminnow in the Upper Colorado River upstream from their current known distribution which is the Price-Stubb Dam (Osmundson and Kaeding 1989; Burdick 1999). Osmundson (1999) suggested that in the Upper Colorado River, aduh Colorado pikeminnow should be able to establish home ranges upstream as far as the head of Debeque Canyon near Debeque which is about 14 miles upstream from the 15-mile reach (RMs 171.0-185.3), once passage is established at Price-Stubb and Government Highline Diversion dams. Osmundson believed that individuals of this species would likely establish yeaz-round home ranges in the Upper Colorado River as far upstream as Debeque, if given the opportunity. He also predicted limited use by this species in reaches upstream from Debeque. Osmundson made this prediction based on his analysis of adult Colorado pikeminnow distribution in the Yampa River, where adults have unrestricted upstream access, with a comparison between the thermal regime there and that in the Upper Colorado River. Osmundson also believed that given the present temperature regime of the Upper Colorado River and the temperature requirements of the Colorado p~eminnow, the upper most end of the 15-mile reach appears to be located near the upstream limits of the optimal range for this species. On the contrary, if Colorado pilceminnow re-colonize and do spawn in these upstream reaches, then stocking fish in this reach may not be necessary. The translocation of large sub- adult and young adult Colorado pikeminnow was designed to provide some initial answers to these questions, assist in determining if further Colorado pikeminnow stocking is needed, and help direct other management activities for this reach. Purpose and Objectives The purpose of the study was to evaluate if translocated, wild and domestic-reazed sub- adult and adult Colorado pikeminnow implanted with radio tags remain in the immediate vicinity of stocking, or move up- or downstream from the stocking site in the Upper Colorado River from Rifle to Palisade. Specific objectives of this study were to: 1. Determine the extent of up- and downstream movements of translocated Colorado pdceminnow following release upstream of the Government Highlme Diversion Dam. 2. Determine if translocated, wild or hatchery-reazed Colorado p~lceminnow will remain and establish residency in stream reaches upstream of the Government Highline Diversion Dam; document the duration that fish remain in upstream reaches. 4