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The extent of the actual affected area can be shown by comparing the piezometric surface map presented in this permit to the piezometric map found in the original permit application for the Keenesburg Mine (Appendix I-2). The maximum distance the piezometric surface has been affected by mining is 4300 feet southwest from the center of the presently mined azea. Also note in Appendix I-2 of this document that recharge of the spoil material appears to be from the west-northwest. Shown in Appendix [-2 is a gently sloping hydrologic gradient from the northwest to the southeast to the approximate center of the mine. This would indicate that higher values of transmissivity/permeability exist in the spoil materials. There are no stream laid deposits holding a stream within 2 miles of the life-of--mine boundary, See Appendix D-l. 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 Appendix I-2, 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 area. Box Elder Creek is located about 3 miles west of the life-of--mine boundary. This is well • beyond the reasonable maximum extent of the affected area. It is likely that a portion of the ground-water flowing through the backfilled mine area will eventually discharge to Box Elder Creek, should mining extend farther west in the future. At this time, however, it is not likely that mining will progress far enough west to effect ground-water flow to Box Elder Creek. As explained in the report of hydrologic investigations, the quality of post mining ground water is not expected to differ substantially from that which now exists. (See Appendix I- l, J-1, J-2). Therefore, neither the quantity nor quality of waters associated with Box Elder Creek or Enrus 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-fI/yr or only 3 gpm, however, based on observations of the active pit area, this discharge rate through the area may be high. 131