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La Plata Coal Draft Finings - 8 - 3) Pursuant to Rule 4.24.2(1), the current and p will be conducted to preserve, throughout the reclamation process, the essential hydrologic alluvial valley floor both within and outside described in the permit applications; and, May 18, 1987 roposed operations mining and functions of the affected areas as 4) Pursuant to Rule 4.24.5, environmental monitoring systems are, or have been, installed, maintained and monitored so as to ensure that the essential hydrologic functions and agricultural utility of the AVF are not impacted. The operation is in compliance with the requirements of this section. IX. s - rcuies A. Probable Hydrologic Consequences ive The probable hydrologic consequences section of this findings document addresses the effects that the La Plata No. 1 mine will have on the ground and surface water systems within and adjacent to the proposed mine area. The information used in this assessment is found in Sections 2.04 and 2.05 of the permit application. Ground Water There are two potentially impacted ground water systems within and adjacent to the La Plata No. 1 mine; the Menefee Formation and the Hay Gulch alluvial system. The probable hydrologic consequences of mining to the Menefee Formation are negligible. The Menefee Formation in the vicinity of the La Plata No. 1 mine appears to be essentially dry. Abandoned mines along the north side of Hay Gulch near the La Plata No. 1 have not been observed to drain water from the portals. No water has drained from or been encountered in the partially developed La Plata No. 1 entry. Due to the hydrogeologic characteristics of the Menefee Formation, perched aquifers, which may be located above the mined seam, may be dewatered during the course of mining operations. Perched aquifers which may be located above the mine are probably limited both in number and in areal extent. There is no documented use of any of these aquifers, nor is there any evidence to suggest that any of these overlying aquifers supply base flow to any local streams or springs. Therefore, impacts to perched aquifers, and the Menefee Formation as a whole, will be minimal. The second ground water system identified near the permit area is the Hay Gulch alluvial aquifer. This aquifer system mey be potentially affected by surface runoff from the mine bench to the sediment pond, and/or discharge from the sediment pond infiltrating into the alluvial body. This infiltration could cause localized increases in total dissolved solids within the alluvium. The probability of this occurring, however, is minimal: The sediment control system at the La Plata No. 1 mine has been designed in such a