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Ground water: The tract's geology can be roughly summarized ae follows: Twentymile Sandstone, Marine Shale Member, and the Lower Coal-Bearing Member that includes the Wedge coal seam (Fig. 1). Of these lithologias, only~the Twentymile Sandstone has been associated with significant groundwater resources. The presence of the Marine Shale Formation under the Twentymile Sandstone ie of great importance. The shale has very low permeability and relative thickness (6B0 feet); thus, there is little hydrologic connection between the Twentymile Sandstone water resources and the coal- bearing zone below the Marine Shale. The interbedded eiltetone, shale, coal, and fine-grained sandstone sequence that directly overlies the Wedge seam in the Lower Coal- bearing Member constitutes an aquifer and has been named the Wadqe overburden aquifer. The Wedge overburden aquifer is characterized by low permeability, limited continuity, low well yields, and relatively poor water quality. Because of these factors, utilization of this ground water is limited to small stock watering installations. The Fieh Creek Sandstone forme a local aquifer within the proposed lease area. It ie approximately 25 feet thick and ie about 200 feet etratigraphically above the Twentymile Sandstone, separated by interbedded sandstone, shale, and eiltetone. water Quality: 8stimates of the water quality of Fieh Creek indicate that dissolved eolide range from 400 mg/L to 1,100 mq/L; and the pH estimates range from 7.l to 8.2. Values for both of these parameters rate as fair-to-good for livestock and wildlife vse (the primary consumers of the water). The chemical characteristics of the surface water are dominated by calcium bicarbonates (CaHCO3), with lesser amounts of magnesium (Hg) and sulfate (SO`) biearBOVate. water quality records exist for the upper Foidel Creek gage (USGS No. 09243800). The gage records describe the extreme specific conductance value being measured at 3,080 microalemene, on December 16, 1987. This level rates as fair-to-poor for livestock and wildlife use. The lower USGS gage does not monitor water quality. Baseline data indicates that natural water quality of the Wedge overburden aquifer is a sod}um bicarbonate type with relatively low concentrations of calcium, magnesium, and sulfate ions. Total dissolved eolide are typically in the range of 400-600 mq/1. The water from the Wedge overburden aquifer ie the water that flows into the mine and ie pumped out and discharged into Fieh and Foidel creeks. In addition to monitoring the springs, two monitoring wells were completed in the Fieh Creek Sandstone aquifer. Water quality from the springs and the wells indicates total dissolved eolide to ba about 387 mg/1 and a pH of S. Further details of hydrologic conditions and monitoring can be found in the Fieh Creek Tract Profile and Site Specific Analysis (Bureau of Land Management, 1982, 1984) and the mine plan permit No. C-82-056 for the Foidel Creek Mine (Cyprus Twentymile Coal Co., 1982).