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Hydraulic conductivities of the sandstones below the coal seams to be mined are variable but low, with average transmissivity of 40 gallons per day per foot, both factors indicating that little water is either recharged, transmitted or discharged from the permit area. Orawdown analysis of two wells, Taylor No. 1 and No. 3, both drilled into the Trout Creek Sandstone, showed an average transmissivity of 40 and 260 gallons per day per foot and hydraulic conductivity of 3.4 and 0.13 gallons per square foot, respectively. Porosity and permeability characteristics of this aquifer were not calculated due to the depth of the sandstone and lack of corresponding data from other locations within the Formation. Storage coefficient for one well, Taylor No. 1, was 0.066, but should only be considered a factor for that well and not the Formation as a whole since no reference data is available. The proposed mining operations are not expected to decrease the water quality or quantity of the Trout Creek aquifer. Since the Trout Creek sandstone member underlies the deepest coal seam to be mined by 800 feet, it is estimated that Colowyo's intention to open two new surface pits should not impact this aquifer in any manner. Underlying the Iles Formation is the Mancos Shale, a unit 5,000 feet thick, consisting of marine shales and limestones. This unit is impermeable and creates the confining base for the Trout Creek sandstone aquifer. Continued operations in the active pit during the last two permit terms, between 1981 and present, support the assertion that little water exists above the coal stratum to be mined. What water does exist has only been experienced under perched conditions. Seeps encountered during operations have been consumed by the face or evaporated from the floor of the pit. Excavation to the lower coal seams has produced dry conditions, indicating there is no lateral nor vertical continuity in the connection between the Iles and the Williams Fork Formations; so the probability of aquifer cross- contamination is negligible. The quality of ground water witin the permit site has been rated poor by the USGS and designated for limited agricultural use only. The chemical composition of the area's water was tested by the USGS in 1978 and found to be somewhat saline, alkaline and hard (see pages 2.04.7-12 and 13 in the permit and Table 1). PH varies from 7.2 to 8.4. The USGS report indicates that concentrations of trace metals rarely exceed health limits. Specific conductivity averages 1440-1390 mmhos with a range between 720 and 2700 mmhos; exceeding EPA secondary drinking water standards (see permit pages 2.04.7-14 through 18 and Table 2). The above factors, coupled with low selenium levels ranging from 0.001 to 0.002, allow the water to be used for stock watering. An EPA report on the "Environmental Effects of Western Coal Mining, Part III" suggested that the alkaline nature of western water -23-