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I I I I , I I I I I I I I I I I I I I CHAPTER IV WATER A. Water Reauirements The total acreage under the Handy Ditch system is approximately 14,000, of which approximately 10,000 is served by Welch Reservoir. The crops grown under the Handy Ditch system include corn, alfalfa, sugar beets, pinto beans and barley. Estimated crop requirements are based on information presented in the St. Vrain Basin Reconnaissance Studv' and consumptive use data collected for the consumptive use transfer of irrigation water owned by the City of Longmont3. These studies indicate that a combined cropping pattern of alfalfa, corn, grain, sugar beets, and pinto beans consumptively uses an average of approximately 19 inches of irrigation water per year (taking effective precipitation into consideration). Assuming a 60% irrigation efficiency, the total water requirements would be approximately 32 inches, or about 2.7 acre-feet per acre. Projecting these irrigation requirements onto the acreage under the Handy Ditch system indicates that up to 37,500 acre-feet of water are required annually to meet theoretical irrigation needs of 14,000 acres. Conversations with Handy Ditch Board members revealed that approximately two acre-feet of water is applied per acre of land under the Handy Ditch system. This estimation corresponds with the annual reports from the Ditch Superintendent (shown in Appendix C). When these twenty years of record are summarized as shown in Table 5, the annual average amount of water 'St. Vrain Basin Reconnaissance Study prepared for Colorado Water Resources and Power Development Authority by R. W. Beck and Associates and Dames & Moore, February 1986. 3City of Longmont Water Transfer Technical Appendix G, Consumptive Use Supplemental Data prepared by Rocky Mountain Consultants, Inc. 1982, decreed in Case Nos. 81CW355, 81CW356, 81CW357, 81CW360, 81CW361, 81CW362. 18