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<br />HELTON & WilLIAMSEN, P.C, <br />CONSULTING ENGINEERS IN WATER RESOURCES <br />384 INVERNESS DRIVE SOUTH, SUITE 144 <br />ENGLEWOOD, COLORADO 80112 <br />PHONE (303) 792-2161 <br />FAX (303) 792-2165 <br /> <br />'-"' 'l"":r' <br />RECt':"~ 'Ii l...!J <br />JU~ 2L \S~ <br /> <br />d \f,.,\r.,r <br />Co1orrl C' "'U 'arl <br />COOsef\lallCO 0 <br /> <br />June 19, 1998 <br /> <br />Mr. Bill Green <br />Colorado Water Conservation Board <br />1313 Sherman Street, Room 721 <br />Denver, Colorado 80203 <br /> <br />Subject Eagle Park Reservoir <br /> <br />Dear Bill: <br /> <br />This letter addresses your questions about exchanges to Eagle Park Reservoir by the <br />Vail Consortium. In the January 1997 feasibility report, I indicated that two modes of operation <br />were possible: 1) operate the reservoir to maximize the dry-year yield, and 2) maximize <br />regulation of the water supply to provide more water in average and wet years for streamflow <br />enhancement. The preferred method is to operate the reservoir conservatively to provide the <br />dry-year yield of 2,013 acre-feet and to optimize the amount of water pumped from the East <br />Fork to the reservoir, thereby minimizing annual power costs. <br /> <br />You also noted the slight difference in my exchange estimates between the feasibility <br />study and the values that Glenn Porzak presented to you. The reduction is due to the larger <br />pumping capacity for the East Fork pumping plant. For the earlier study, I used a capacity of 5 <br />cfs. This capacity has been increased to 6 cfs to allow capture of the diurnal fluctuating <br />streamflows. It also allows the pumping plant to divert more water in priority in average flow <br />years, thereby reducing the exchanges. <br /> <br />The four-year period of 1975-1978 was the critical period of operation and it established <br />the dry-year yield. In a couple of other years, the exchange volumes were a little larger; <br />however, the reservoir spilled in the following year, thereby negating the benefit of the <br />exchange. Accordingly, I recommend that the participants commit a total of 628 acre-feet of <br />exchangeable water (1977 exchange amount) to the Eagle Park Reservoir project. <br /> <br />Please call if you have any questions. <br /> <br />Sincerely yours, <br /> <br />HELTON & WilLIAMSEN, P.C. <br /> <br />~M/~ <br /> <br />Thomas A. Williamsen <br /> <br />TAW/mlc <br /> <br />cc: Glenn E. Porzak, Esq. <br />Dennis Gelvin <br /> <br />C:\V103\061998,TAW <br />