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West E[k Mine Table 65 Surface Areas of Alluvial Deposits Near the West Elk Mine Stream Total Area mil Alluvial Fan Area mil North Fork Gunnison River 1.40 0.29 S Nester Gulch 0.04 Minnesota Creek 0.68 D Fork Minnesota Creek 0.14 East Fork Minnesota Creek 0.29 South Fork Minnesota Creek 0.07 The soils in this location aze primarily deep clays. The Haplaquoll soil predominates. It is associated with beaver activity and commonly exhibits mottled conditions in subsurface horizons. The alluvial origin of this material is plausible because of the beaver activity and downstream channel blockage from a landslide and from Minnesota Reservoir dam which was placed at the blockage point. Normally the soil is saturated with water at or near the surface. Because of absence of good aeration, organic matter content is high. The valley floor in this reach of the Dry Fork would be incapable of supporting agricultural activities without proper drainage. Approximately 20 percent of the total alluvial fill deposits above Minnesota Reservoir has an artificially high water table as a result of backwater conditions from the reservoir pool, This area could not be drained adequately without removing the reservoir. Even with adequate drainage on the remaining azea, the agricultural development would be restricted to grasses and pasture because of the high elevations and short growing season. Furthermore, the beaver ponds and willow thickets aze an important factor in the general ecological picture, since they help regulate stream flow, provide water for domestic animals and wildlife, and provide wildlife cover. The Hydrology and Mining Methods Sections detail the mining activities currently scheduled to take place under Dry Fork and the safeguazds that will be taken to preserve the hydrologic integrity of Dry Fork. Atlantic Richfield, with guidance from OSM and OMLR personnel, is developing a subsidence monitoring program. The information obtained will be used to refine the subsidence control plan for the mining azea under Dry Fork, if necessary, to protect the hydrologic balance. Thus water availability at Minnesota Reservoir will not be affected by the mine. Additionally, Atlantic Richfield is working with the various ditch and reservoir companies holding water rights on Minnesota Creek and its tributaries to develop an augmentation plan. This plan, when finalized, will detail mitigation efforts for short and long term effects to water rights holders should unforseen factors affect the hydrology of Dry Fork. The other location of possible alluvial deposits within the mine permit area is within the west branch of Sylvester Gulch as shown on (on map 66). The Sylvester Gulch Valley widens slightly in this location and there is a sharp break in slope from the valley sides. However, the alluvial origin of the valley deposits at this location is doubtful. The soils aze a deep clay Arquistolls. • They aze susceptible to mass movement and aze typically found on side hill locations (Reconnaissance Soil Survey, West Elk Study Area, 1976). The lack of base level control that 2.06-4