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three aquifers exhibit artesian conditions in central portions of Twentymile Park Basin. The quality in all aquifers is moderately poor but is tolerable for use as a drinking supply. The geologic structure created by folding and faulting within the Twentymile Pazk Synclinal Basin affects the direction of flow within the rock aquifers. In the permit and adjacent areas, the direction of ground water flow in the bedrock aquifers is down dip toward the center of the Twentymile Park Basin. Faults in the area produce localized fracture zones within the rock strata. These zones of increased permeability, in turn, increase the potential For vertical and horizontal movement of ground water within the rock strata. However, experience to date in the Foidel Creek mine shows little to no inflow along the fault zones at the level of the Wadge coal seam. Some inflows were encountered in 9R and 6R gateroads as they were developed into the Eastern Mining District. These inflows appeazed to be localized, and tapered off over time. The underlying 700-foot shale and the overlying shales and siltstones of the upper Williams Fork Formation and the Lewis Shale Formations produce the confined artesian conditions within the Twentymile sandstone aquifer. To the northeast, the Twentymile sandstone rechazges the alluvial aquifer and provides base flow to the tributaries of Trout Creek down gradient of the mine. Salts in the Twentymile sandstone waters are predominantly sodium bicazbonate and result in TDS levels of 150 mg/1. This aquifer is tapped for domestic needs, and to a minor extent, for livestocks The alluvium of Trout Creek and its tributaries is an important source of ground water. The alluvial bodies are used as water supplies, provide subirrigation to vegetation, and supply base flow to the streams. The alluvial bodies aze recharged by both the streams and the bedrock aquifers. The mine is located in the upper reaches of the Yampa River Basin. The permit area and adjacent azeas are drained by Foidel Creek, an intermittent stream, and Fish Creek and Middle Creek, both perennial streams. Fish Creek drains east into Trout Creek whereas Foidel Creek drains northeast to Middle Creek before Middle Creek joins Trout Creek. The quality of water in the Fish Creek and Foidel Creek drainages have been affected previously by surface mining upstream and downstream of the underground mine's existing surface facilities. Alluvial valley floors (AVF) are identified downstream of the mining area at the confluence of Foidel and Middle Creek, and on Trout Creek from its confluence with Middle Creek downstream to the Yampa River. Permit Revision No. 3 declassified portions of Foidel and Middle creeks previously classified as AVF's. Detailed discussion concerning alluvial valley floors can be found in Section B, part XVIII of this document as well as Exhibit 7j of the permit. The local climate is semi-arid with a mean annual precipitation of 14.6 inches. Approximately 45 percent of this precipitation occurs during the growing season of April though September. High temperatures generally range from 70-80°F in the summer months to below freezing in the winter months. Normally, a significant snowpack resides on the ground for 4-5 months during the winter. s State Engineer Well Records