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<br />Upper Gunnison River Water Conservancy District <br /> <br />) <br /> <br />commercial demand associated with seasonal visitation. Short term projects currently <br />identified meet up to 275 acre feet of this demand, potentially leaving up to 1,890 acre <br />feet of unmet demand in Gunnison County. <br /> <br />Agricultural Water Demand and Supply <br /> <br />After meeting with Mr. DINatale we are more comfortable with the numbers used <br />for the consumptive use within the Gunnison Basin. However, we still believe that these <br />numbers are lower than the actual numbers. In support of that assertion, we have <br />attached information from the Colorado Division of Water Resources ("DWRM) and <br />Colorado State University. DWR Division 4 uses the Pochop method for determining <br />consumptive use in water court applications. This modified Blaney -Criddle method <br />takes into account elevation. The spreadsheet currently being used in Division 4 was <br />previously emailed to Mr. DiNatale. Additionally, Professor Don Smith, from CSU, <br />conducted a Iysimeter study in the Gunnison Basin for the past five years. A summary <br />explanation of his findings is attached to this letter. <br /> <br />~ <br /> <br />The SWSI demand analysis shows an average irrigation water requirement in the <br />Gunnison Basin of 1.49 af/ac. (Irrigation water requirement is the amount the crop <br />needs after effective precipitation is accounted for.) The field studies conducted in the <br />Upper Gunnison Basin indicate on average irrigation water requirement of 22.68 inches <br />or 1.89 af/ac. If the higher consumptive use values developed from our local field data <br />are used - the annual shortages are even greater than the figures shown in the draft <br />SWSf documents to date. Our studies show an irrigation water requirement that is 20% <br />greater than that used by SWSI for the upper basin. This higher level of demand would <br />mean that the shortage in the basin is more like 25,338 acre feet on average, and <br />reaching maximums of 46,842 acre feet on a one year basis. Similarfy, if the data set <br />being used by SWSI included the 2002 drought year records, the shortages would likely <br />be greater than the 21, 115 acre feet average and 39,035 acre-feet maximum shortage <br />indfcated. <br /> <br />As indicated at the Gunnison Basin Roundtable, we are uncertain about the <br />amount of Irrigated acreage used by SWSl. The explanation provided to us was that <br />the acreage by county was an estimate but the discrepancies between the numbers <br />used in by SWSI and numbers the Upper Gunnison District uses based on engineering <br />studies are significant. Please see attached memo from Mr. Jim Slattery. For example, <br />SWSI Gunnison Basin Agricultural demands are calculated using 2,700 acres for Hinsdale <br />County, 14,757 acres for Saguache County and 68,107 acres for Gunnsion County for a <br />total acreage in the Upper Gunnison Basin of 85,564 acres. The Upper Gunnison's <br />engineering consultants, Helton & Williamsen, P.C., came up with a value of 75,345 <br />acres - 1,916 acres for Hinsdale County, 13,286 for Saguache County and 60, 143 acres <br />for Gunnison County. While SWSI' s acreage apparently includes all of Gunnison <br />County and Helton & Williamsen's numbers do not include any of the acreage under <br />the North Fork of the Gunnison River, the Irrigated acreage under the North Fork within <br /> <br />4 <br />200 East Virginia Avenue 'V Gunnison, Colorado 81230 <br />Telephone (970) 641-6065 V Fax (970) 641-7606 V <br />ugrwcd@co,gunnison.co,us <br />