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<br />n fi~' 'P" () <br />''J~. . ',,). ) <br /> <br />. <br /> <br />Hydrology <br /> <br />In addition to the streamflow gaging stations mentioned <br />above, there is a Parshall Flume at the east end of the Moffat <br />Tunnel for measuring water which Denver imports from the Colorado <br />River drainage. This water is diverted into Denver's South Boulder <br />diversion canal above the gage on South Boulder Creek at Eldorado <br />Springs. <br /> <br />Surface Water Supply <br /> <br />The surface water supply of the St. Vrain Creek basin is <br />composed of natural basin runoff and importations. The latter <br />consists of transbasin imports from the adjacent Little Thompson <br />River basin located to the north, and transmountain diversions trom <br />the Colorado River basin by the Colorado-Big Thompson Project. In <br />the period of study, 1947 to 1965, recorded natural basin runoff <br />from the mountainous area averaged 237,100 acre-feet annually. If <br />adjusted to reflect diversions around the gages, natural runoff from <br />the mountainous area would have averaged 255,300 acre-feet annually. <br /> <br />. <br /> <br />Transbasin imports from the Little Thompson River are made by <br />the Ish Reservoir Company for use by lands served by the Mead Lateral <br />in the lower St. Vrain Creek area. Historically, these imports have <br />averaged 2,300 acre-feet annually. <br /> <br />Colorado-Big Thompson Project imports to the St. Vrain Creek <br />basin are delivered through the St. Vrain Supply Canal from Carter <br />Lake, located about 10 miles northwest of Longmont. The St. Vrain <br />Supply Canal serves several ditches directly from canal turnouts, <br />releases water to the St. Vrain Creek at a point just below the <br />town of Lyons for diversion to ditches havi,ng C-BT shares, and <br />provides water for the Boulder Creek Supply Canal for delivery to <br />the Boulder Creek area. Colorado-Big Thompson Project water is <br />delivered to lands along the South Platte River via the South <br />Platte Supply Canal. Because this water is not used in the <br />St. Vrain Creek basin, it was not included in either basin inflow <br />or outflow. <br /> <br />Colorado-Big Thompson Project water deliveries to the <br />St. Vrain Creek basin were begun in the middle of the 1947-1965 <br />study period. Deliveries to the St. Vrain Creek area began in <br />1953 and to the Boulder Creek area in 1955. When describing the <br />average annual C-BT project imports,the volume of water delivered <br />in the 13-year period 1953-1965,was averaged out over the entire <br /> <br />. <br /> <br />12 <br /> <br />,,'-,\.'C' <br /> <br />k' <br /> <br />