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province. Structurally, the area is underlain by the southwestern limb of the northwest plunging Watering Trough Syncline, which produces dips in the local strata of four to eight degrees northeast. Although faults have been identified in the area, none have been identified within the mine permit area. Coal mined by the operation is within the upper unit of the Williams Fork Formation. The coals are separated by siltstones, mudstones and sandstones. At the base of the upper unit of the Williams Fork Formation, 200 to 300 feet below the coal zone, is the 100 foot thick ledge forming Twentymile Sandstone. The Twentymile Sandstone outcrops below the southern end of the mine site. The Twentymile Sandstone and lower lying Trout Creek Sandstone are aquifers of significant regional extent. Other ground water bearing zones occur in the coals and local lenticular sandstones within the mining area. Recharge areas for most of these strata are on the south facing slopes along the Williams Fork River Valley south of the mine. Ground water tends to flow along the dip of the strata (northeast) and some of the localized lenticular sandstones discharge in the form of springs north of the mine. Within the permit area are portions of the Hayden Gulch, Dowden Gulch and Dry Creek drainage basins. The majority of the mine area occurs within the Hayden Gulch drainage. These basins contain ephemeral streams which respond predominantly to spring runoff from snowmelt. Hayden and Dowden Gulch are tributaries to the Williams Fork River which is perennial in nature. The region is characterized by a semi-arid steppe climatic regime. The prevailing wind is from the west and southwest and average annual precipitation is 16.1 inches. The growing season in the region varies from 28 days to 94 days; the time span depends greatly upon the elevation of a given area. Soils at the mine site are of the order mollisol and suborder boroll. These are soils formed in cool climates which are characterized by a very dark colored base-rich surface layer. Variability of the characteristics of the soils on the permit area is primarily due to slope, aspect and topographic position. Deeper soils are located in the valley bottoms and footslopes while the shallower soils occupy the upslopes. Vegetation is also distributed in response to the micro-climatic influences of the north-south trending ridge and valley complex within the area. Sagebrush communities dominate the richer, deeper soils of the valley bottoms and gentle slopes. Oak communities dominate the generally drier south and west facing slopes in the area, and often intergrade into the other communities in the form of patches of dense oak growth. Aspen dominated communities are found in clumps in small hillside swales and gentle north slopes in the permit areas; these areas 4