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• EXECUTIVE SUMMARY This feasibility report developed and evaluated concepts for fish passage facilities at the existing Redlands Diversion Dam on the Gunnison River near Grand Junction, Colorado. Colorado squawfish and razorback sucker are two species that are threatened with extinction in the Colorado River system. The purpose of the facility is to allow these two species to reestablish themselves in a portion of their historic range. However, this facility is considered experimental in nature due to the lack of exact biological criteria for the two species. Therefore, best available biological and technical criteria for Colorado squawfish and razorback sucker, or similar species, were used to evaluate the concepts. From the initial concepts, five alternates were selected for further study. The alternates were evaluated for their biological and technical merit, impacts on Redlands Water and Power Company operations, and construction, operation, and maintenance costs. The recommended alternate (No. lA) is a vertical slot/orifice fish ladder located adjacent to the existing sluice gates. Refer to Plates 6 and 7 for plan and profile views. This ladder has three downstream fish- way entrances and one upstream exit. .This alternate also includes a fish trap, an auxiliary attraction water supply, bar screen at the existing headgates for fish protection, and a trash shear boom upstream to protect the fish ladder. Provisions for an automated trash rake system have been made if trash becomes a severe problem at the bar screen. This alternate was selected because of the effectiveness of its fish entrance location in the main river channel (most likely location for attaining successful fish passage), flexibility of operation to attract and pass fish upstream, and lower initial construction cost. If final design reveals complica- tions with reduced spillway capacity, then a higher cost alternate (No. 1) may be reconsidered. The total design and construction cost of this alternate is $782,900. The recommended alternate is scheduled to be designed in early 1987. Construction of the fishway is scheduled to commence in the fall of 1987 with completion by spring of 1988.