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<br />INTRODUCTION <br /> <br />Historic flows of the Yampa River, largest tributary of the Green <br />River, have not yet been altered by dams. However, a number of water <br />development projects are planned which may significantly impact flows, <br />and consequently, the endangeredfi sh fauna. The Yampa Ri ver and the <br />upper Green River in Dinosaur National" Monument (DNM) are important for <br />endangered fishes, including the Colorado squawfish (Ptychocheilus <br />lucius), and the humpback chub (Gila cypha) (Miller et al.1982). <br />Because of potential conflicts between proposed water projects and the <br />survival of endangered fishes, the Fish and Wildlife Service (FWS) and <br />the National Park Service (NPS) proposed a study of the Yampa River in <br />1980. The goal of this study was to supply the FWS with information for <br />Section 7 of the Endangered Species Act, and to provide FWS and NPS with <br />information needed for planning purposes. The FWS and NPS signed a <br />cooperative agreement in the spring of 1981 to study fishes of the Yampa <br />and upper Green rivers within DNM. The Colorado Division of Wildlife <br />(CDOW) also cooperated in this study and continued an ongoing fish <br />monitoring program in the Yampa River. In addition, FWS initiated <br />studies on the upper Yampa, above DNM, with funds provided by Congress. <br />The results of the198~ study, published in part in 1982 (Miller et al. <br />1982), and 1983 (Miller et al. 1983), documented spawning of Colorado <br />squawfi sh in the lower 20 mil es (32 km) of the Yampa Ri ver and provi ded <br />other information about endangered fishes in DNM. NPS-CDOW and FWS also <br />conducted radiotelemetry field investigations in DNM in 1982, and \~ick <br />et al (1983) provided data that supported the Colorado squawfish spaw- <br />ning and movement data obtained by FWS in 1981. <br /> <br />In the spring of 1983, NPS took the lead in initiating several <br />studies (physical and biological) for DNM. Two divisions of the FWS, <br />the Division of Ecological Services (ES) and the Colorado River Fishery <br />Project (CRFP) participated in this interagency effort. This report <br />prov; des data obtained by the CRFPStudy in 1983, and also summari zes <br />1981 and 1982 FWS studies in DNM. CRFP study Objectives included . <br />locating 1983 spawning areas for Colorado squawfish, obtaining habitat <br />preference data using radiotelemetry, and demonstrating spawning success <br />by collecting Colorado squawfish larvae. <br /> <br />DESCRIPTION OF STUDY AREA <br /> <br />The.Colorado River Basin is further separated into upper and lower <br />basins at Lee Ferry, Arizona. The upper basin is subdivided into three <br />major river systems or hydrologic subbasins: the Green, Upper Mainstem, <br />and the San Juan (Figure 1). The Yampa River, with an average annual <br />discharge of 1.5 million acre feet, is the largest tributary to the <br />Green River. Arising on the western slope of the Rocky Mountains near <br />