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Three categories of potential aquifers exist in the general area: alluvial deposits associated with the North Fork of the Gunnison River and its tributaries, the Rollins Sandstone, and lenticular discontinuous sandstones of the Upper Mesaverde Formation. The lazgest alluvial aquifers are associated with the North Fork of the Gunnison River. Smaller, more isolated alluvial aquifers are associated with several tributaries of the North Fork. The Rollins Sandstone is the only known sandstone with sufficient porosity and lateral extent to be considered a regional bedrock aquifer. The only wells in the region which are completed in this aquifer are located near the Hawk's Nest Mine along the North Fork. Localized perched bedrock aquifers exist in the discontinuous, lenticulaz, fine-grained sandstones of the Upper Mesaverde Formation. The amount of ground water in these sandstones is controlled by faulting and fracturing of the strata (secondary porosity) and the topography of the recharge area. No known wells are completed in the sandstones of the Upper Mesaverde Formation above the mine workings. The valley in which the towns of Paonia and Somerset are situated is semi- arid, with annual precipitation averaging about 15 inches per year. Mean annual precipitation increases with elevation, reaching over 40 inches per year near the summit of Mt. Owen. The May-September precipitation is five inches for the lowlands and 13 inches for the mountain peaks. This indicates that snowfall patterns play an important part in determining the hydrologic conditions of the area. Temperature extremes at Paonia have ranged from -28oF in January to 100oF during July and August. The average annual temperature is approximately 49oF. Snowfall averages 58 inches per year. The general area in which the Sanborn Creek Mine is located is chazacterized by steeply sloping mountains covered either with tall shrub vegetation, particularly oakbrush and serviceberry, or stands of pinon and juniper trees. Drainages in the area are lined with riparian vegetation communities along the stream banks. Some of the more level areas have been cleared and support limited livestock grazing; however, for the most part, the surrounding land is undeveloped and is used primarily as wildlife habitat. Recreational activities such as big game hunting, trapping, fishing, and off-road driving also occur in the general area. The portal facilities area neaz the confluence of Elk Creek and the North Fork is located at the contact of the alluvium of the North Fork and steep upland sedimentary formations. Sanborn Creek Mine portal facilities are just east of Sanborn Creek or approximately one mile east of the town of Somerset. Sanborn Creek Mine 8 Permit Revision No. 3