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WATER REPLACEMENT PLAN SPECIFIC DESCRIPTION EAST ROATCAP DRAINAGE BASIN L TOPOGRAPHY The East Roatcap Creek is an ephemeral stream tributary to Roatcap Creek which is tributary of the North Fork of the Gunnison River. East and West Roatcap Creeks meet in Section 26, T.13S., R.92W. and meet at elevation approximately 6,600 feet above sea level. At the fat northern stretches of the basin, the water is intercepted by the Overland Ditch. The East Roatcap drainage pattern extends 21,000 feet. The average gradient is approximately 12X. The actual stream channel is steeper than average in the southern part of the basin just before it meets the West Roatcap Creek pattern. The East Roatcap Drainage basin is approximately 3.6 square miles. 0.96 square miles or approximately 26.SY. of the basin is outside of any existing or pro- posed lease. East Roatcap represents 23. 1X of the drainage area contained within the whole of Roatcap Creek Drainage area. The ~.ast Roatcap Creek drainage pattern is at the bottom of two steeply inclined banks facing generally southeast and southwest. The flow to the creek is generally south. ALLUVIAL/COLLUVIAL DEPOSITS The East Roatcap drainage occupies steep walled, gently sinuous to nearly • straight canyons. The streambeds contain basaltic boulders of 4-18" in dimen- sion, with minor local deposits of sand and gravel. These sediments are con- sidered dominantly colluvium, deposited in degrading streams with subsequent reworking and size dimension of a minor amount to alluvium status. There are no flood plains or terraces which are distinctive of alluvial valleys and which could provide areas large enough to be significant for crop production by irri- gation or subirrigation. Major flows occur during spring snow melt and after heavy rains. For additional information, refer to Section 2.04.7 in the Orchard Valley Mine Mining and Reclamation Permit Application. SOIL TYPE The soil conservation map of this tributary designates the soils in the drain- age pattern as being fluvents, flooded, with a source of a soil from a variety of rocks and subject to sporadic movement of sediments by fast-moving waters. Potential sources of sediments are outcrops of the Mesaverde Formation in the steep slopes at the west end of the drainage, and landslide the deposits on both sides. Although this drainage pattern, like most of the upland draws, has continuous subflow seepage, the soil appears to be deep and well drained. For additional information on the specific soil in the area, please refer to the Paonia Area Soil Survey, January 1981, U. S. Department of Agriculture, Soil Conservation Service. The basin is dominated by Delson Loam to Delson Very Stony Loam, 20 to 60 percent. •