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. 10 due to evacuation of cold water from the reservoir but would result in warmer reservoir temperatures and releases in July and August (Tables 4-7). May and June surface spills would occasionally warm downstream temperatures. Most of the reservoir euthrophication, stagnation, and phosphorus retention problems of high level withdrawal would be reduced under single outlet conditions. The deep (low-level') 'reservoir withdrawal would constantly remove cooler water and draw down the fresher, warmer, and aerated water, thus reducing the long period of stagnation needed to redissolve heavy metals. Should anerobic conditions still develop in the reservoir, aeration would be necessary to suppress resolution of heavy metals. Figures 6 and 7 (from the aeration studylJ) indicate a minimum dissolved oxygen level of 4 mg/L would be maintained. D. Fish and wildlife Historically, the Uncompahgre River was not an outstanding fishery. It does, however, support a small population of cold water game and nongame fish. Most habitat in the Uncompahgre River between Ridgway Dam and Colona is relatively deep and fast with a significant portion of riffle. Pool habitat makes up less than 1 percent. There are no Federally listed threatened or endangered species in the Uncompahgre River. However, the Colorado squawfish inhabits the lower Gunnison River and the Colorado River. Also present in the Colorado are humpback and bony tail chubs, both listed as endangered by the Fish and wildlife service. Trout fisheries in the project area are limited by relatively poor water quality, annual high flows, turbidity, and lack of good quality avail- able habitat. The Colorado Division of Wildlife electrofishing survey in 1974-75 identified rainbow trout, brown trout, flannelmouth sucker, white sucker, bluehead sucker, sculpin, and dace. The study also disclosed a lack of young trout which suggests that trout populations are essentially the result of stocking and that very little natural reproduction is taking place in the river. There is some brown trout recruitment from tributaries to the Uncompahgre. With the completion of the Dallas Creek Project, releases from Ridgway Dam are expected to be of improved water quality as the heavy metals and other suspended solids settle out in reservoir sediments. Decreased spring flows below the dam will also reduce scouring and bedform movement which should improve spawning habitat during May and June, especially for rainbow trout. Good fish populations may develop downstream with the improved physical and chemical environment and consistent flow regime during. Although spawning habitat appears to be limited in this area, a moderate amount of natural reproduction (primarily brown trout) should take place. 1/ Johnson, P. L. , 19a1, Ridgway Reaeration Technical Study, Bureau of Reclamation, Engineering and Research Center, Denver, Colorado.