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Probable Hydrologic Consequences New Elk Mine 7 <br />I® <br />Figure 3. Generalized Configuration of the Long -Term Water Table in the Northern Portion <br />of the Raton Basin (Watts, 2006a) <br />3.2.1 Alluvial Aquifer <br />Alluvium and unconsolidated sediments are present along the valley floor adjacent to the Purgatoire River <br />and are an important source of domestic and agricultural water supply for area residents. Drilling records <br />from the Colorado Department of Water Resources (CDWR) indicate that the alluvial thickness may <br />exceed 70 feet in some areas, but most wells access groundwater from alluvium that is less than 30 or 40 <br />feet thick. WWL (1980) drilled eight boreholes in alluvium near the permit area and concluded that <br />groundwater was present only in alluvium that was in direct hydraulic connection with the Purgatoire <br />River, and that the thickness and extent of the alluvium is limited. Three of the boreholes were drilled near <br />the Allen Mine. The remaining five boreholes were installed near the Maxwell Mine. <br />The extent of unconsolidated deposits including alluvium, colluvium, and terrace gravels has also been <br />mapped in Apache and Ciruela Canyons (Wyoming Fuel Company [WFC], 1985). The deposits are <br />generally thin and are narrowly confined along the canyon floors. Alluvium in the upper reaches of the <br />drainages is unsaturated or may be seasonally saturated during spring runoff. Alluvium in the lower <br />reaches ofthe canyons near the Purgatoire River is saturated. <br />Groundwater levels in alluvium are available front boreholes that were installed by WWL (1980), from <br />well records that were obtained from CDWR, and from monitoring wells located near the East Portal Shaft. <br />WWL reported that the depth to water in the Purgatoire Valley Alluvium ranges from 4 to 6 feet below <br />ground surface (bgs) and that groundwater levels are largely controlled by the river level. Well records <br />from CDWR indicate that water levels in the alluvium range from 3 to 15 feet bgs (Table 4). Locations <br />4164A. 110421 Whetrrone Airxiatet <br />TD CA D,.6:64 WAADo 19Y A IN) II <br />•� �ew,..�v .i,w oss.w w._ euw euw +ww <br />Lnr..wmme„'nm�mnusY. <br />. nu,I 80.5 <br />