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-11- Although underground mining would occur in areas adjacent to the alluvial valley floor, all surface disturbances are located more than a mile upstream from the alluvial valley floor. The alluvial valley floor would not be undermined by the proposed operations. 2. The proposed surface coal mining operations would not materially damage the quantity and quality of water in surface and underground water systems that supply those alluvial valley floors or portions of alluvial valley floors. All of the surface flow from the permit area drains to the North Fork of the Gunnison. The applicant has monitored the largest two drainages crossing the permit area. During this period, Lone Pine Gulch has experienced no flow. Sylvester Gulch has experienced ephemeral stream flow. The record yield of 208 acre -ft/yr. in 1978 is less that 1% of the mean annual flow in the North Fork of the Gunnison River. Surface flow supplied to the alluvial valley floor along the North Fork comes primarily from areas upstream from the proposed permit area and this flow is regulated by Paonia Reservoir located approximately 6 miles upstream of the alluvial valley floor. Mining operations would require approximately 150 acre-f t. of fresh water per year for sanitary and drinking water. The possible effects of this water removal upon the water supplied to the alluvial valley floor has not be assessed. The applicant's discussion of probable hydrologic consequences has identified no anticipated changes in surface water quality. All runoff from disturbed surface areas, including runoff from the waste disposal site, would drain through an approved sediment control system. All discharges would be 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 would be 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 5-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. Loss of this water would not significantly decrease the water supply to the alluvial valley floor.