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-14- upstream of the alluvial valley floor. Mining operations require approximately 150 acre-ft. of fresh water per year for sanitary and drinking water. This water is withdrawn from the North Fork during spring runoff when water rights are available and used throughout the year. The wastewater is then treated and returned to the hydrologic system through periodic discharges from the waste water treatment plant. This results in negligible loss to the system. 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 foc 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 probably 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 focm. At present it is not possible to predict the water quality of these springs. However, they would be such a minor contribution of the water supplied to the alluvial valley floor, no degradation of water quality in the alluvial valley floor is anticipated. 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. Alluvial Valley Floors - Monitoring (Rule 4.24.5)