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• 4.5.6 Potential Impacts There ere no atrenm laid deposits holding a stream within 2 miles of the ash disposal, life-of-mine boundary. Ennis Draw, which lies immediately on the east of the boundary, does not hold a stream. Ennis Draw is a relatively broad, flat, topographic low in which no stream channel is defined. No evidence of a presently existing perennial, ephemeral, or intermittent stream in Ennis Draw has been observed. There is subsurface evidence that a stream once existed in the draw, but these deposits have been covered over by the existing wind blown deposits. As shown in Map 4.6.3 <e), the subsurface water system of Ennis Draw has been effectively isolated from the mining activity presently being conducted adjacent to the draw. There has been none, nor is there anticipated to be, a significant impact to the ground-water levels in this arse. Box Elder Creek is located about 3 miles west of the proposed ash disposal site. At this time, however, it is not anticipated that ash disposal will progress far enough west to effect ground-water flow to Box Elder Creek. Aa explained in the report of hydrologic investigations, the quality of post ash disposal activities on the ground-water is not expected to differ substantially from that which now • exists. (See Water Auality Data, Section 4.5.7, Appendix B, Ash test results and Water Quality, Appendix C). Therefore, neither the quantity nor quality of waters associated with Box Elder Creek or Ennis Draw are expected to be affected. In any case, the discharge through the life-of-mine area is very small. The ground-water discharge through the area was previously estimated to 5.4 ac-ft/yr or only 3 gpm, however, based on observations of the active pit area, this discharge rate through the area may be high. 9.5.7 Ground-water Ouelity and Monitoring Since the initiation of the formal groundwater sampling program in January 1982, twenty quarters of sub-surface water quality information has been collected from monitor wells in and around the Keenesburg Mine. This ground-water monitoring program has delineated baseline conditions concerning ground-water movement and quality in and around the active operations area. The results obtained from date collected in the field and from comprehensive water quality analysis indicate that surface and ground-water quality has not been impacted from the natural pre-mine conditions. In addition, mayor ground-water movement patterns have not been influenced or interrupted by mining activities. • -34-