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<br />D . Trout Fisheries <br /> <br />1 ~ Ove",iew <br /> <br />This Plan offers an opportunity to maintain and in some cases enhance existing <br />conditions for the high-quality trout populations in the river4 Fishery management is a <br />very complex science. Streamflow management is only one of many factors affecting <br />trout population. Diseases, fishing pressure, stocking regulations, etc., also have a <br />dramatic effect on fish populations. CDOW fishery management goals of today will not <br />necessarily be the same in the future, but the overall goal to maintain, protect and enhance <br />the South Platte river system's aquatic resources will remain the same. <br /> <br />The Plan has four main reservoir operation goals for trout fishery management. which <br />are listed by prioritY4 The first goal is to maintain minimum streamflows below Spinney, <br />Eleven Mile~ and Cheesman Reservoirs. Streamflows below minimum levels deprive <br />trout of habitat and may have serious impacts to trout populations. The second goal is to <br />minimize streamflow fluctuation. Steady transitions from low streamflow to high <br />streamflow, and vice versa, allow fish time to move into new habitats as water levels <br />change. The third goal of the Plan is temperature moderation. Improving stream <br />temperatures by mixing top and bottom reservoir releases will decrease physiological <br />stress and susceptibility to disease in trout populations4 The last goal is to manage peak <br />streamflow" High streamflows, although naturally occurring, may negatively impact the <br />recruitment of young fish into the population. However, high streamflows are also <br />periodically necessary in order to maintain channel stability and capacity, and to transport <br />fine sediment downstream. Due to limited storage space and water rights and other <br />constraints, managing peak streamflows is the least attainable of the four fishery <br />management goals4 There are few opportunities to attenuate peak streamflows by <br />reservoir operations. The extent to which Denver Water can pass peak flows is unknown <br />at the present time. Denver Water and Aurora will strive to operate Spinney, Eleven Mile, <br />and Cheesman reservoirs to attenuate peak streamflows recognizing the limited potential. <br /> <br />2. Mainstem Plan <br /> <br />Table 2: Desired Streamflow for Fishery Management <br />Minimum Optimum Range <br />Location Period (cfs) (cfs) <br /> <br />Spinney Release <br />Eleven Mile Release <br />Cheesman Release <br /> <br />Year round <br />Year-round <br />August-March <br />April-July <br /> <br />20 <br />20 <br />35 <br />40 <br /> <br />50 to 150 <br />50 to 100 <br />50 to 150 <br />100 to 225 <br /> <br />N :\Supply\ Waage\wildscen\attachb.doc <br /> <br />B~6 <br />