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The applicant's discussion of probable hydrologic consequences identified no anticipated changes in surface water quality. All runoff from disturbed surface areas, including runoff from the waste disposal site, drains through an approved sediment control system. All discharges are made under the conditions of the applicant's NPDES permit, and any effluent must meet the water quality standards for the receiving streams. If necessary, discharges are treated to assure compliance with water quality standards. As a result, no degradation in the quality of surface waters supplied to the alluvial valley floor is anticipated. Any ground water supplied from strata with the potential to be affected by the proposed operations is minimal. No major aquifers have been identified in either the coal seam or the overburden. Springs in the area are associated with lenticular sands, local faulting and fracturing, and landslides. Most of the springs in or adjacent to the five year permit area are located along Sylvester Gulch (see Exhibit 2.6.2.A). Since part of this watershed would be subject to subsidence, some of these springs could dry up. However, these springs, which supply less than 50% of the flow in Sylvester Gulch, are currently used as a water source for the Tony Bear Pipeline which is now owned by WECC. Loss of this water would not significantly decrease the water supply to the alluvial valley floor. No significant degradation in ground water quality is anticipated. Following mining, new springs, fed by water supplied by the accumulation of water in the underground workings, could form. At present, the water quality of these springs under worst case assumptions would approximate the water quality of flooded mine workings at the Oliver Mine adit where total dissolved solids concentrations range between 1050 and 1900 mg/1 (see CHIS-Affects to Surface Waters section). However, flow from these springs would be such a minor contribution of the water supplied to the alluvial valley floor, no degradation of water quality in the alluvia] valley floor is predicted. 3. Surface coal mining and reclamation operations are conducted to preserve, throughout the mining and reclamation process, the essential hydrologic functions of alluvial valley floors not within the affected area (Rule 4.24.2). None of the mining activities are located within the alluvial valley floor and the natural geologic and hydrologic characteristics of the valley floor would not be disturbed. In addition, mining operations are not expected to affect the quantity and quality of surface and ground water that supply the alluvial valley floor. 23