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_12_ floors. The alluvial valley floor probably continues downstream, but for those areas no determination is needed at this time due to limited impacts predicted. Alluvial Valley floors - Findings 1. The surface coal mining operations would not interrupt, discontinue, or preclude farming on an alluvial valley floor (Rule 2.06.8(5)). Although underground mining would occur in areas adjacent to the alluvial valley floor,_all surface disturbances are located more than mile upstream from the alluvial valley floor. The alluvial valley floor would not be undermined by the operations, nor will they be significantly affected by surface and ground water impacts from the surface operations. 2. The 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 than 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 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-ft. of fresh water per year for sanitary and drinking water. This water is withdrawn during spring runoff when water rights are available and used throughout the year.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 has 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 t by the proposed operations is probably minimal. No major been identified in either the coal seam or the overburden. r o be affected aquifers have Springs in „~