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...."'.... 1'\'11,,' '., ':) , J '..; ~.~ '.# ." " . Hydrology have not been included in this report because the diversions are above the recording gages utilized for this study. Historical municipal and industrial water use in the basin has involved only a fraction of the total surface water supply available. Longmont and Boulder consume the largest amounts of M&I water. Diversions by Longmont averaged 4,500 acre-feet annually during the 1~47-1965 study period. Of this total, 3,800 acre-feet was normal natural flow diversions and 700 acre- feet was imported Colorado-Big Thompson Project water obtained by exchange. The water diverted for Boulder averaged 7,300 acre-feet per year during the study period. Of this total, 2,200 acre-feet was Colorado-Big Thompson Project water obtained by exchange and 5,100 acre-feet was normal natural flow diversions. A, water buiget for the basin is included as table 3. Agricultural Water Utilization . During the 1947-1965 study period, direct-flow diversions for irrigation in the St. Vrain Creek area (Water District No.5) averaged 102,400 acre-feet annually and diversions to ditches in the Boulder Creek area (Water District No.6) averaged 96,100 acre- feet annually under direct-flow rights. Of these diversions, 700 acre_feet in the St. Vrain Creek area and 2,200 acre-feet in the Boulder Creek area were imported Colorado-Big ~10mp80n water exchanged for natural flow by Longmont and BouLier. Water obtained under agri- cultural storage rights during the study period averaged 16,000 acre- feet annually in the St. Vrain Creek area and 14,400 acre-feet annually in the Boulder Creek area. The natural-flow diversions totaled 228,900 acre-feet annually. Of the historic annual water diversions to Union Reservoir, 3,900 acre-feet was later returned to St. Vrain Creek for delivery to lands in the main stem of the South Platte River basin. Subtracting this from the average historic St. Vrain Creek basin natural_ flow diversions for agriculture of 228,900 acre-feet results in a net agricultural use of 225,000 acre-feet annually. Historic annual diversions of Colorado-Big Thompson Project water for agriculture averaged 22,200 acre-feet in the St. Vrain Creek area and 5,100 acre-feet in the Boulder Creek area. Diversions of water imported from the Little Thompson River basin averaged 2,300 acre-feet annually. Direct-flow and storage diversions of native and imported water for agriculture were 139,000 acre-feet in the St. Vrain Creek area and 115,600 acre-feet in the Boulder Creek area, or a total of 254,600 acre-feet. . 17 k ",,i.;l. .i'_ :,>..<'-,-_