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<br />. <br /> <br />11 <br /> <br />Two thousand man-days of downstream fishing would accrue as benefits <br />in the no-power alternatives. Power addition, however, may slightly affect <br />brown trout spawning which occurs October to November and incubation, which <br />takes 48-60 days in 50. F water. Fall and winter water temperatures would <br />range from approximately 35-42. F and may extend the incubation period to 90 <br />or even 120 days. <br /> <br />All power alternatives outlined in Chapter 11 utilize a two-unit <br />powerplant and produce identical flow regimes below Ridgway Dam. Between <br />October and January, flows would drop 11 cfs instead of 28 cfs as shown in the <br />no-power alternatives. This should cover the maximum amount of spawning area <br />and improve brown trout egg incubation and fry survival. <br /> <br />Flows during the rainbow trout spawning period of May and June would <br />be less with the addition of power, but should not effect reproduction. In <br />fact, spawning success could potentially increase due to the reduction in <br />excessive velocities and bed scouring. <br /> <br />Water temperatures would vary within each alternative but are well <br />within the tolerances of rainbow and brown trout (35-68. F). Table 1 shows <br />average temperatures falling within the optimum range of 50-60. F. Cold water <br />bottom releases from power alternatives during May and June should not impact <br />rainbow trout except for a possible spawning delay until June when temperatures <br />reach 50. F, or a lengthening of the hatching period due to the cooler (48-55.F) <br />temperatures. From a temperature standpoint, none of the proposed power <br />alternatives would have a significant impact on existing or potential trout <br />populations in the Uncompahgre River below Ridgway Dam. <br /> <br />The only time Ridgway Reservoir releases would affect temperatures <br />of the Uncompahgre River below its confluence with the Gunnison would be <br />during spring runoff. The slight decrease in temperature at this time would <br />be negligible since the flow of the Uncompahgre amounts to only 12 percent <br />of the confluence at that time (Dominguez Reservoir Project, Reservoir and <br />River Temperatures Study, July, 1980). Thus the project would not significantly <br />impact the existing warm water fishery (including endangered species) in the <br />lower Gunnison or Colorado Rivers. <br /> <br />From the standpoint of dissolved oxygen levels, 5 mg/L is the <br />mlnlmum concentration that will sustain a reservoir trout fishery through the <br />summer stagnation period. This level is met or exceeded year round at most <br />places in the reservoir. (See Tables 2-5) <br /> <br />Power alternatives would result in slightly lower reservoir content <br />than the no-power alternatives. The greatest differences would appear February <br />through May when surface area would be reduced a maximum of 75 acres, or 8 <br />percent of the total. As a 30 percent area reduction is needed to significantly <br />impact reservoir fisheries, it does not appear that any of the power alternatives <br />would be detrimental to the fishery or fisherman use. <br /> <br />The addition of hydroelectric power or changing outlet works design <br />would have little or no effect on wildlife. All power alternatives would <br />