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<br />OOiJ8J8 <br /> <br />Cimarron Dred~in~ Environmental Assessment <br /> <br />.' <br /> <br />--s.~... <br />10,_. <br /><---:0" <br />~.$.~ar <br /> <br />\ <br /> <br />Morrow Poirr Reservoir <br /> <br />IV.' <br /> <br /> <br />\.. <br /> <br />\. <br /> <br />J( <br />/' <br />g( <br />1\ <br /> <br />, <br />\ <br />Figure 2. - Reservoirs of the Aspinall Unit <br /> <br />(concrete wall) located about 320 feet downstream from the dam controls the depth of the water <br />in the stilling basin (USAR 1981). In the fall of 1965, about 1,200 feet of the Gunnison River <br />.' (tailrace) downstream from the dam was excavated to lower the tail water and increase head on <br />the turbines. The channel work lowered the tail water elevation about 10 feet to an elevation of <br />6743 feet with a slope of2 feet for every 1000 feet (see Appendix A). Excavation for the <br />channel work required a 35-foot minimum bottom width trapezoidal channel. Since the <br />construction of Morrow Point. high flows in the Cimarron River have transported gravel and <br />other materials into the old Gunnison River channel (upper end of Crystal Reservoir) at its <br />confluence with the Cimarron River. The gravel disposition has resulted in raising the surface <br />water elevation in the tail bay, causing back pressure on the generator turbines, that in tum. has <br />reduced power production efficiency of the generators. Power efficiency losses to the United <br />States are estimated at about 1.14%, which represents about 5,608 megawatt hours per year in <br />power generation at a value of about $98,539 per year. The goal of the proposed project is to <br />return the tailrace to the 1965 elevation to improve power production efficiency. <br /> <br />9 <br />