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-8- Description of the Environment The 2,050 acre Hawk's Nest permit area lies within the drainage basin of the North Fork of the Gunnison, which is tributary to the Colorado River jFigure A). The North Fork of the Gunnison within the vicinity of the mine cuts a deep canyon which separates high tablelands to the south of the river from the steep slopes of Grand Mesa to the north. Downstream of the mine site in the vicinity of Paonia the North Fork Valley widens out into a broad alluvial valley. The Hawk's Nest permit area is situated on the north side of the North Fork and is drained by nine ephemeral tributaries to the North Fork; "A" Gulch, "B" Gulch, "C" Gulch, Hoopola Gulch, Bardin Canyon, Sand born Creek, Coal Gulch, Hawk's Nest Creek, and Thompson Creek. All of these tributaries have steep strewn gradients, and watersheds with steep slopes. The area tributary to the mine's permit area is mountainous with a range in elevation from 6,080 feet along the North Fork southwest of the mine to 9,682 feet at the swnmit of Pilot Knob to the north. The elevations on the permit area range from 6,080 feet along the North Fork to over 8,200 feet on the northern permit boundary. The average slope over the permit area is 40%. The climate of the region is typical of the Rocky Mountains in that precipitation rates and temperature are dependent on elevation. Precipitation increases with increased elevation and temperature decreases wiih increased elevation. The valley in which Paonia and Somerset are situated is semiarid with annual precipitation rates averaging 14.2/ inches. hlean annual precipitation exceeds 25 inches at the summit of Pilot Knob. The May to September precipitation is 6 inches for the lowlands in the North Fork valley and between 8 to 10 inches for Pilot Knob. This indicates that snowfall patterns and snowmelt runoff play a dominant role in the hydrology of the region. Snowfall at Paonia averages 58 inches per year. The temperature extremes measured at Paonia range between -28oF in January to 100oF during July and August. The average annual temperature at Paonia is 49oF. The Hawk's Nest Mine is located in the Somerset Coal Field. Mock strata exposed in the Somerset Coal field, from oldest to youngest, consist of the Mancos shale, the Mesaverde Formation, the Rudy or Wasatch Formation, and Iyneous intrusive rocks. All bedrock strata exposed within the permit and adjacent areas are of the Mesaverde Formation. This Formation consists of a 2,500 foot thick sedimentary sequence of coals, sandstones, siltstones and shales which are divided into four members; the Rollins sandstone, the Lower Coal Bearing (Bowie) member, the Upper Coal Bearing (Paonia) member, and the Barren member.