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West Elk Mine 2003 Annual Hydrology Report • 4.6 Mine Rater Balance A mine water balance was developed as a tool for water management to quantify the water entering and leaving the mine. The WY2003 mine water balance is summarized below and illustrated on Figure 3. Inflows (water entering the mine) include: • Raw water intake (North Fork diversion, 468 ac-ft) • Mine Inflows (faults, coal outcrops, and drips, 161 ac-fr) Total Inflow = 629 ac-ft Outflows (water exiting the mine) include: • Water in produced coal and GOB (150 ac-ft) Mine sump discharge and drilling water (432 ac-ft) • Mine ventilation moisture (50 ac-fr) Miscellaneous mine seepage and evaporation (20 ac-ft) Pond evaporation (22 ac-ft) WTP (8 ac-ft) Runoff from surface operations\pond discharge (253 ac-ft) Total Outflow = 935 ac-ft The total volume of water entering the mine during WY2003 was 629 ac-fr versus a total outflow of 935 ac-ft, a net difference of+306 ac-ft (surface operations discharge). 5.0 ASSESSMENT OF MINE INDUCED HYDROLOGIC IMPACTS 5.1 Surface Water MCC maintains a network of 17 stream flow gaging stations throughout the permit and lease areas, listed in Table 2. The locations of the stations are shown on Map 2. Daily mean flow tables are shown in Appendix A. Stream hydrographs are presented in Appendix B and water quality is in Appendix C. 5.1.1 Area Stream Water Quantity and Quality Mining activity has approached only two perennial streams Minnesota Creek and Deep Creek. Long wall mining operations in the Minnesota Creek drainage took place from July 1998 to February 2001. Since March 2001, there has been longwall mining in the Deep Creek drainage. Based on water quality and flow monitoring data (see appendices A, B, and C) there have been no • apparent mining induced impacts to the water quality or quantity of these streams. 30 September 2004 HydroGeo, Inc.