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for sub-irrigation would be affected. As discussed in the statement of probable <br />hydrologic consequences, these effects would be short termed. With reclamation <br />and removal of the sediment control system, these effects would be mitigated. <br />Most of the mining that would occur in the Bolton Draw watershed has already <br />occurred under the previously permitted operations. <br />Surface coal mining and reclamation operations would be conducted to preserve, <br />throughout the mining and reclamation process, the essential hydrologic functions <br />of the alluvial valley floor. <br />Mining operations would not physically disturb the alluvial valley floor. With <br />successful reclamation and removal of the sediment control system, the surface <br />water flow to the draw would be restored and water chemistry would return to <br />natural conditions. <br />The applicant has suggested that the release of sediment-deficient waters from the <br />sediment ponds would cause downstream erosion (780-124). Should this occur, <br />the erosion would begin immediately downstream from the sediment ponds on <br />unnamed tributazies to Bolton Draw. Given the infrequent nature of streamflow <br />in this area, erosion would be observed and could be mitigated before it could <br />spread to Bolton Draw and cause channel incision in the alluvial valley floor. <br />Alluvial Valley Floors -Sudduth Draw -Findings <br />1. The proposed surface coal mining operation would not interrupt, discontinue, or <br />preclude farming on an alluvial valley floor. <br />None of the proposed mining operations would be located within the alluvial <br />valley floor. Final mining activities in Pit 3 would be located immediately <br />adjacent to the alluvial valley floor. A buffer would be left along Sudduth Draw, <br />according to Map 15a. No mining activities would encroach upon the AVF. <br />2. The proposed operations would not materially damage the quantity and quality of <br />water in surface and subsurface water systems that supply those alluvial valley <br />floors or portions of alluvial valley floors. <br />Mining in the Sudduth Draw watershed would affect the quantity and quality of <br />surface water supplied to the alluvial valley floor as described in the applicant's <br />statement of probable hydrologic consequences (pages 780-123 to 780-126jjjjj). <br />Mining would reduce surface flow in Sudduth Draw by approximately three <br />percent of the annual yield. The ion balance of the surface water could be altered, <br />and salt loading on the stream could be increased by 2.7 kg per year. These <br />changes do not represent a significant change in surface water quantity or quality. <br />As discussed in the summary of probable hydrologic consequences, the effects are <br />temporary and would be mitigated by reclamation. <br />Marc Mine Permil Renewal 04 <br />11 January, 2002 <br />-25- <br />