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Wobus, et. al, (1985) and the Dakota and Purgatoire Formations. Water percolates downward <br />through these units to an impermeable layer in the upper Morrison Formation where it forms a <br />perched aquifer. This normally occurs within the upper 200 feet of the formation, generally <br />above the level of Fourmile Creek; some thin aquifers may occur at or slightly below the creek <br />level, and could locally discharge small amounts of ground water into Fourmile Creek. <br />The Fountain Formation is recharged in the vicinity of the well by precipitation on flat-lying <br />outcrops north of the well and on tilted beds that outcrop to the east (about one mile away). The <br />tilted exposures of the Fountain Formation east of the well are probably the source of most of the <br />recharge of the deep aquifer. Some recharge also occurs in tilted beds of the Fountain west of <br />Canon City (about 4 miles away) and migrates to the east towards the axis of the Chandler <br />syncline, located about I.5 miles west of the well. North of the well, extensive deposits of the <br />unconsolidated Louviers Alluvium (Wobus, et. al, 1985) fill the valley floor and overlie the <br />Fountain Formation. Some shallow recharge into the Fountain Formation may occur via <br />precipitation that seeps through the surficial unconsolidated deposits north of the well into <br />fractures in the upper part of the Fountain Formation. <br />Surface Water/Ground Water Interactions <br />Fourmile Creek, a tributary to the Arkansas River flows southward towards the Arkansas Basin <br />and is adjacent to the Park Center Well. Based on the well log of the Mutual Oil Co. well, there <br />is about 2650 ft. of sediments between the producing aquifer and Fourmile Creek. Because of the <br />great thickness of impermeable to semi-permeable sediments between the river and the producing <br />zone in the Fountain Formation, there can be no hydraulic connection between the river and the <br />aquifer. Vertical hydraulic conductivity values of sedimentary beds can be about one tenth to one <br />hundredth the value of horizontal conductivity values, so except for fracturing or jointing that <br />may be present, the vertical movement of ground water will be minimal. The low hydraulic <br />conductivity value combined with the great thickness of sediments means that pumping of the <br />Park Center Well will not cause any depletion of Fourmile Creek. <br />Any effects of pumping the Park Center Well on surface water should be indicated by losses in <br />strearnflow along Fourmile Creek. A comparison of streamflow data at two USGS gages can be <br />made for this purpose. There are two gaging stations operated by the USGS on Fourmile Creek, <br />one at the upper end of Fourmile Creek near the town of Victor, the other at the lower end near <br />the confluence with the Arkansas River. By comparing mean monthly flows during the winter <br />months when base flow conditions are approximated (i. e. no snowmelt, no runoff events due to <br />thunderstorms, and no diversions for irrigation), an estimate can be made of the stream <br />interaction with the ground water flow system (i.e. gains or losses in streamflow). These <br />conditions generally exist during the period from October to March. Using water year 1994 data, <br />the mean monthly streamflow at the gage on Fourmile Creek near the confluence with the <br />Arkansas River showed increased streamflow compared with the flow measured at the upper end <br />of Fourmile Creek for the months of December 1993, January 1994, and February 1994. In <br />March 1994 there was a loss of 3.6 cfs (see figure 5). These changes in streamflow occur in <br />Fourmile Creek as it flows through Garden Park to the confluence of the Arkansas River, a <br />distance of about 14 miles. The Park Center Well is about 5 miles above the gage at the <br />5 <br />