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Red Mesa Aquifer Groundwater Study — Interim Report 2002 <br /> Because the La Plata River system flows primarily are controlled by runoff patterns, flows <br /> typically peak during the spring runoff periods and are often dry or very low during the rest of <br /> the year. It is during these low-flow periods that the La Plata Compact is most difficult to <br /> satisfy. Figure 4A shows the La Plata River average daily flows for year 2001. Flows increased <br /> in mid-April, peaked in late May (up to a maximum of 296 cfs) and decreased by late June. This <br /> compares to the 84 year average (see Figure 4B) where flows increase in April, peak in late May <br /> (up to 204 cfs on May 27 for the average of the 84 years) and decreased by late July. Base flow <br /> conditions of approximately 5 cfs existed much of the remainder of the year 2001, compared to <br /> approximately 10 cfs over the 84-year average. The minimum flow at Hesperus was <br /> approximately 3 cfs in 2001, while over the 84-year average it was approximately 7 cfs. <br /> Groundwater mapping was done near the peak on May 17 and 18, 2001 (see Figure 5) and near <br /> the lowest point of the hydrograph on December 16 and 17, 2001 (see Figure 6). <br /> 3.0 GROUNDWATER DATA <br /> 3.1 Data Collection <br /> Well monitoring began in April 2001. A total of 42 wells were selected on the basis of location <br /> and availability. Thirty-four of the 42 wells are domestic wells, which were volunteered for use <br /> in the monitoring program. These 42 monitoring well locations are shown on Figures 3, 5, 6, and <br /> 8. Eight of the 42 wells are monitoring wells positioned within the flood plain of the La Plata <br /> River. The Bureau of Reclamation originally monitored these wells under previous A-LP <br /> studies. Monitoring of these wells was continued in this study. <br /> The wells were monitored on 14 dates from April 13, 2001 to October 10, 2002. During each <br /> site visit, static water levels were measured and compiled in a database. Collection frequency <br /> ranged from every two weeks to once every two months. The timing of data collection was <br /> dependent upon the amount of fluctuation in'groundwater levels. During periods of high runoff <br /> 991-077/031 Wright Water Engineers, Inc. Page 6 <br /> Interim Report <br />