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Recovery Program participants are we77 aware that total control of nonnative fish species in the large rivers of the Upper Colorado River Basin is not possible. A large volume of fishery literature exists to demonstrate that total control of fish in such waters is unrealistic (Wiley and Wydoski 1993). However, it is believed that even partial contro I of the nonnative fishes wi 77 reduce predation on and competition with the endangered Colorado River fishes. All ponds where nonnative fi shes are removed and the adjacent river envi ronments wi 77 be monitored to evaluate the response of both endangered, native, and nonnative fishes. During the development of a strategic plan for control of nonnative fish species (Tyus and Saunders 1996), the Recovery Program participants reviewed potential control methods and examined the life histories of the nonnative fishes to determine whether certain life stages were most vulnerable .to control (Lentsch et a1. 1995). During their discussions, the Recovery Program participants decided that preventive measures to manage/control the distribution and population expansion of nonnative fishes was a top priority (Wydoski 1995). Several preventive measures that were identified included (1) completion of the IIProcedures for Stocking Nonnative Fish Species in the Upper Colorado River Basin", (2) preventing/minimizing nonnative fish escapement from riverside ponds, (3) chemical reclamation of riverside ponds, and (4) preventing/ minimizing nonnative fish escapement from large reservoirs. The "Procedures" were completed and adopted by the Colorado Division of Wildlife, Utah Division of Wildlife Resources, Wyoming Game and Fish Department, and U.S. Fish and Wildlife Service (Colorado Division of Wildlife et al. 1996). Floodplain ponds were inventoried by Mitchell (1995) to determine the number and identify those with outlets to the rivers that could be screened to prevent chronic escapement of nonnative fishes. Screens (Burns 1966; Schnick et al. 1982) will be installed on ponds in the future where appropriate. The berms of some ponds may be increased in height so that they would not connect with the river unless a 50-year or larger flood occurred. Ponds that are above the 50-year floodplain can be stocked with nonnative, warnwater fish species under the "Procedures for Stocking Nonnative Fish Species in the Upper Colorado River Basinll (Colorado Division of Wildlife et a1. 1996). A scope-of-work was developed by the Colorado Division of Wildlife and approved through the Recovery Program to begin the chemical reclamation of floodplain ponds (Martinez and Nesler 1996). A feasibility study was' completed for insta77ation of fish control structures on reservoirs with warnwater fish species and with outlets to Upper Basin rivers (Miller and Laiho 1997). The focus of the feasibility study was on Elkhead Reservoir (Yampa River) and Highline Reservoir (Colorado River). Therefore, a number of Recovery Program efforts are underway to control or manage nonnative fish species in the Upper Colorado River Basin to reduce predation and competition by nonnative fishes on the endangered fishes. 3. Some anglers would like to have warmwater angling opportunities from the floodplain ponds. 29