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The combined impacts of the Golden Eagle and New Elk Mines include dewatering of the coal seam and overburden aquifers, depleting flow in the stream/alluvial aquifer system, depression of piezometric surface in confined aquifers beneath the coal aquifer, deterioration of the quality of ground water flowing through abandoned coal workings into coal aquifer, and deterioration of water quality in the stream/alluvial system. Due to the separation of Golden Eagle and New Elk Mines from the Raton Creek and proposed Rimrock Strip Mines, no significant cumulative effect is expected on the separate ground water systems that exist in these areas. Since discharges and surface runoff from all of these mines do reach the Purgatoire River, however, there is some potential for cumulative impacts on the quantity and quality of the water in that river. The Raton Creek and Rimrock Strip Mines do not restrict the volume of surface flow to the Purgatoire River through the tributary drainages that these mines adjoin. In fact, discharge from the Raton Creek Idi ne may i ncrease the volume of flow i n Raton Creek. No significant adverse cumulative impact on the quantity of water in the Purgatoire River will then result from the Raton Creek and Rimrock Strip Mines. The TDS of water in Raton Creek are increased by the mining activity at Raton Creek, but, due to the volume of water in the Purgatoire River, any change in TDS values in the River brought about by this increase would be undetectable, It is not anticipated that the small Rimrock Strip Mines, i.e., 20 acres, will appreciably raise the TDS value even in the surface drainages nearby which are tributary to the Purgatoire River. Asa result, the impacts of the Raton Creek and Rimrock Strip are cumulatively insignificant as regards the quality of water in the Purgatoire River. The Allen and Maxwell coal seams lie close to one another in the stratigraphic column, separated by approximately 20 feet of interburden material. Disturbance of roof, floor, and interburden material during mining, and subsidence after mining, will result in the breakdown of the interburden strata. Asa result, hydrologic communication is expected to occur between the two coal seams, and ground water impacts are expected to be cumulative. The following assessment considers the two coal seams as one aquifer. During operations, dewatering would occur in the coal aquifer and the drawdown of the piezometric surface could extend outward to approximately 3 miles from each mine. Since the mines are adjacent to each other, a portion of these affected areas would overlap. Within that zone, drawdown effects would be additive. After the cessation of operations, mine water would no longer be discharged and the abandoned workings would fill with water. The ground water level and piezometric surface would partially recover. A permanent depression in the piezometric surface of the coal aquifer would exist in the vicinity of the flooded workings of the mines. The depression would not be large, but it may extend 3 miles from each mine. Approximately twice as much ground water would flow through the flooded mine workings than flowed through the undisturbed coal prior to mining. This mine water flow would, however, be restricted by the low permeability of the -26-