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of a strategic plan to remove or reduce existing populations of nonnative fish species from habitat used by the endangered Colorado River fishes (Tyus and Saunders 1996). One of the highest priorities in the Recovery Program's strategic plan for control of nonnative fishes is prevention of chronic escapement of nonnative fish species from off-channel ponds along the Upper Colorado and Gunnison rivers that could further exacerbate existing interactions of nonnative fishes (i.e., predation and competition) on the endangered fishes. Most of the floodplain ponds are located in bottomlands that were inventoried by Irving and Burdick (1995). Recovery Program participants believe it is unlikely that the endangered fishes will be recovered (i.e., establish viable, self-sustaining populations through natural reproduction) until problems associated with nonnative fishes is addressed. D. Backqround Information. The fish fauna in most reaches of the Colorado River Basin bears little resemblance to the historic fish community.The geologic isolation of the Colorado River and its tributaries from oth~r watersheds gave rise to a fish fauna in which 64% of the native species are found nowhere but in the Basin (Miller 1959). In addition to being unique, the fish fauna of the Colorado River Basin is depauperate when compared with other North American river basins with only 36 species of native fishes. The native fishes of the Colorado River Basin were adapted to the natural aquatic conditions (e.g., extremely variable streamflows and high sediment loads) . These fi shes evolved together and, more than 1 i ke 1 y, formed a stable fish community where competition and predation were balanced. The main fish predator on the native fishes in the Upper Colorado River Basin was the Colorado squawfish. The other native species occupied various niches that reduced competition for limited resources, particularly food and habitat. 1. Recovery Proqram. The Recovery Implementation Program for Endangered Fishes in the Upper Colorado River Basin (Recovery Program) was implemented as a cooperative effort among the States of Colorado, Utah, and Wyoming; U.S. Bureau of Reclamation; u.S. Fish and Wildlife Service, Western Area Power Admi ni strat ion, water development interests, and environmental organizations with a goal of allowing water development to proceed to meet the needs of society in the Upper Colorado River Basin while seeking solutions for recovery of the endangered fishes (U.S. Fish and Wildlife Service 1987a). The Recovery Program was intended to serve as a reasonable and prudent alternative to avoid jeopardy to the continued existence of the endangered Colorado River fishes and their critical habitat from historic and new water development projects' in the Upper Colorado River Basin in consultations related to Section 7 of the Endangered Species Act. A detailed description of the Recovery Program is provided by the U.S. Fish and Wildlife Service (1987a), an environmental assessment of its implementation is provided by the U.S. Fish and Wildlife Service (1987b), and its evolution along with pertinent background is summarized by Wydoskiand Hamill (1991). 4