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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />has estimated that approximately 10 percent of the area's precipitation becomes <br />recharge and that this makes up approximately 53 percent of the total recharge to <br />the area's aquifer (USGS Water Supply Paper 1658, pp. 38 and 77), Approximately <br />45 percent of the aquifer's recharge comes from surface water inflow, and the <br />remaining 2 percent comes from subsurface inflow. Groundwater is discharged <br />naturally through springs and seeps, by evapotranspiration, by subsurface outflow and <br />artificially, from wells (USGS Water Supply Paper 1658, pg. 34), <br />Insufficient data are available to determine the rate at which the aquifer is <br />being recharged versus the rate it is being discharged, but the water table in the <br />Fort Lupton area has fallen by 3 to 5 feet in recent years (10 to 15 percent of the <br />saturated thickness of the aquifer). In 1963, the USGS concluded that the aquifer <br />of the South Platte River valley between Denver and Greeley had almost 2 million <br />acre feet of water in storage that could be withdrawn (USGS Water Supply Paper <br />1658, pg, 2). <br />The regional water table is defined by water levels in wells tapping the <br />unconfined aquifer. The water table slopes gently to the north-northwest towards the <br />South Platte River. In its report for EP A on the PCE contamination problem of <br />Wells No.6 and No, 7, Ecology and Environment, Inc., estimated the average slope <br />of the water table, or hydraulic gradient, in the Fort Lupton area to be 0.0019 <br />(Report of Sampling Activities, Ecology and Environment, Inc" pg, 11). This value <br />also agrees with that determined by the USGS (USGS Water Supply Paper 1658, <br />pg. 113). This is a low hydraulic gradient due to the nearly flat surface of the water <br />table in the area. The water table has been reported to occur as shallow as 5 feet <br />below the ground surface in the Fort Lupton area, but during the well testing that <br />was performed as a part of the Well Study in 1992, the water table was found to <br />occur at depths ranging from 15 to 22 feet. During the past two years, the static <br />water level has dropped 3 to 5 feet, and some shallow wells in the area have gone <br />dry, <br />The City conducted a well testing program in 1992 to determine the aquifer <br />characteristics in the vicinity of each of its five operating wells. A summary of the <br />aquifer characteristics that were determined is listed in Table 3-1. <br /> <br />25325.100; 12/09194 <br /> <br />3-4 <br />