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_17_ Mining operations would not physically disturb the alluvial valley floor. With successful reclamation and removal of the sediment control system the surface water flow to the draw would be restored and water chemistry would return to natural conditions. The applicant has suggested that the release of sediment deficient waters from the sediment ponds would cause downstream erosion (780-124). Should this occur, the erosion would begin immediately downstream from the sediment ponds on unnamed tributaries to Bolton Draw. Given the infrequent nature of streamflow in this area, erosion would be observed and could be mitigated before it could spread to Bolton Draw, and cause channel incision in the Alluvial Valley Floor. Alluvial Valley Floors - Sudduth Draw - Findings 1. The proposed surface coal mining operation would not interrupt, discontinue, or preclude farming on an alluvial valley floor. None of the proposed mining operations would be located within the alluvial valley floor. The final mining activities in pit three would be located immediately adjacent to the alluvial valley floor. A buffer would be left along Sudduth Draw, according to Map 15a no mining activities would enroach upon the AVF. 2. The proposed operations would not materially damage the quantity and quality of water in surface and subsurface water systems that supply those alluvial valley floors or portions of alluvial valley floors. Mining in the Sudduth Draw watershed would affect the quantity and quality of surface water supplied to the alluvial valley floor as described in the applicant's statement of probable hydrologic consequences (p. 780-123 to 780-126jjjjj). Mining would reduce surface flow in Sudduth Draw by approximately 3~ of the annual yield. The ion balance of the surface water could be altered, and salt loading on the stream could be increased by 2.7 kg/y r. These changes do not represent a significant change in surface waters quantity or quality. As discussed in the summary of probable hydrologic consequences, the effects are temporary and would be mitigated by reclamation. 3. Surface coal mining and reclamation operations would be conducted to preserve throughout the mining and reclamation process, the essential hydrologic functions of the alluvial valley floor. Mining operations would not physically disturb the alluvial valley floor. Minor changes in surface water supplied to the alluvial valley floor (as discussed above) would occur during the mining phase of the operation. With successful reclamation and removal of the sediment control system, the quantity and quality of surface flow supplied to the AVF would return to natural conditions.