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Willow Beach NFH - is located in Arizona on Lake Mohave, 11 miles downstream from Hoover Dam. It is a trout production facility which has produced and reared Colorado River endangered fishes since 1973. Water is supplied by pumping directly from Lake Mohave. Water temperature ranges from 54-560F during the year. To warm the water for production of endangered Colorado River fishes, two adjacent 8'xlOO' concrete raceways were interconnected and the water recirculated using electric pumps, which increased the water temperature to 700_740F from June through September. During these months, the air temperature ranges from 900 to 1200F. Ten raceways have been modified and are still available for rearing endangered fishes. These modified raceways are well suited for both spawning and rearing endangered Colorado River fishes and with ferti- lization are very productive. The open water supply from Lake Mohave has lead to disease problems (Ich, tapeworm, and anchorworm), although prophylactic treatments have been effective in controlling these organ- isms. The maximum production of 2-3 inch fish which could be expected with this present system would be 100,000 or less. This is well below the estimated need of 500,000 3-inch fish. To produce 500,000 fingerlings/year would require some major modifica- tions of this facility. The hatchery facilities presently occupy the land area adjacent to the lake. The only unoccupied area is up a canyon above the residences (Figure 1). A full study of the terrain has not been made, as yet, but restricted land availability precludes major expansion of the hatchery facilities. An alternative that could in- crease production would be to enlarge the present recirculation system and modify the design to include biofiiters so water velocities could be increased to make the units self-cleaning. A second alternative would be to use geothermal ground water in a flow-thru system. Wells were drilled on the station some time ago but were found to be too warm and too high in dissolved solids for domestic use. Unfortunately, well records and water quality analyses were not kept and the wells have been filled and sealed. New wells would have to be drilled to explore this source of warm water. If the production of Willow Beach NFH could be economically increased to 500,000, 3-inch fingerlings by 1988, other problems would still remain. One problem is the distance from the Upper Basin. Fish distribution trips would exceed 500 miles over mountainous terrain and take 16 hours of driving one way. Also, Willow Beach NFH being removed from the part of the river where the Colorado squawfish still occur, precludes using their homing instinct as a tool in their management. However, the station is well located to serve the Lower Basin and is in the historical range of the Colorado squawfish' and bony tail chub, but not the humpback chub, as far as is known. To use Willow Beach NFH, Region 6 would have to work out an agreement for meeting trout production needs of Region 2 and endangered fish needs of both Regions 2 and 6. 27