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-7- <br />Steven's Gulch, East Roatcap Creek, and Coal Gulch are intermittent to <br />ephemeral drainages that only flow part of the year. Localized deposits of <br />colluvial material reworked by fluvial processess are present within the <br />general area, primarily within the Steven's Gulch, West Fork Terror Creek, and <br />Roatcap Creek drainages. These deposits are generally 20 to 30 acres in size <br />and provide industrial (Steven's Gulch), domestic (Long Draw), and <br />agricultural (Morrell Cow Camp) water sources (page 39, Section 2.04.7 of <br />Volume 1). Several smaller occurrences of saturated alluvial/colluvial <br />deposits are associated with the streams in the permit area; however, none of <br />these is currently supporting agricultural use. <br />The flow of water in Terror Creek and in the North Fork of the Gunnison River <br />is strongly influenced by irrigation structures along these stream courses. <br />The Overland Ditch intercepts and distributes water from the upper reaches of <br />Terror Creek. The flow in the North Fork is controlled by Paonia Reservoir <br />and water withdrawals by several irrigation ditches: the Fire Mountain Canal, <br />Stewart Ditch, Farmers Ditch, and Paonia Ditch. In addition, there are two <br />pipelines that will withdraw water from the Steven's Gulch Well Field. The <br />first is currently in operation and is operated by the Pitkin Mesa Pipeline <br />Company. The second pipeline carries water from the Steven's Gulch Well Field <br />to the site of the proposed Roatcap Creek portal facility. <br />There are malty springs and ponds within the permit and hydrologically <br />adjacent area. Based on available data, it appears that most of these springs <br />and ponds are intermittent and depend upon seasonal precipitation and recharge <br />from shallow colluvial/alluvial sources. <br />The Orchard Valley Mine lies on the southeast margin of the Piceance Basin. <br />Sedimentary rocks ranging from late Cretaceous to early Tertiary age, and <br />dipping 5 degrees North, are exposed in the mine areas. Structural-strati- <br />graphic cross-sections and isopach maps are presented in Volume l0A <br />{Confidential Appendices), and the mine area geology is presented on Map 2-2. <br />Coal is to be produced from the D Seam of the Upper Coal member of the Mesa <br />Verde Formation. The Mesa Verde is a 2,500-foot-thick sequence of sedimentary <br />beds overlain by the Ohio Creek Congolomerate and underlain by the Mancos <br />Shale. The Mesa Verde Formation is composed of four members; the Rollins <br />sandstone, the Upper and Lower Coal members, and the "Barren" member. <br />The lowermost member of the Mesa Verde Formation, the Rollins sandstone, is a <br />white to buff-colored, well-sorted, medium-grained sandstone, ranging from 150 <br />feet to 200 feet thick in the permit area. The Lower Coal member overlies the <br />Rollins sandstone and consists of interbedded sandstones, siltstones, coals, <br />and shale. The unit averages 265 feet thick in the permit area and bears <br />three significant coal seams--the "A", "B", and "C" seams. <br />