_GENERAL DOCUMENTS - C1981017 (283)

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-32- Surface Water The major river of this study area is the Roaring Fork River. The Roaring Fork joins with the Colorado River at the town of Glenwood Springs. For the purpose of this CHIS, the mouth of the roaring Fork will serve as the cumulative surface water impact reference point. All mines considered in this CHIS are tributary to the Roaring Fork. Please refer to Figure No. 1 for locations of all affected drainages, and Tables 2 and 3 for surface water quantity and quality characteristics. The Coal Basin Mines affects the Coal Creek Drainage. This stream joins the Crystal River at the town of Redstone. The Snowmass operation is located within Thompson Creek's drainage basin just north of Coal Basin. Thompson Creek joins the Crystal River 11 miles downstream from Redstone. The Crystal River flows toward the town of Carbondale, where it joins with the Roaring Fork River. One-half mile downstream of this confluence is the Snowmass Coal Company loadout facility. Five miles downstream of the confluence of the Roaring Fork and the Crystal Rivers, is the confluence with Fourmile Creek. The Sunlight Mine is located on Fourmile Creek, 7.2 miles above this confluence. The Roaring Fork gaging station (the point defining the study watershed) is located 4.2 miles downstream of the Fourmile Creek confluence with the Roaring Fork River at Glenwood Springs, Colorado. Streams in the region cross Vie outcrops of the Lower Mesaverde Group ( Iles and Lower Williams Fork Formation) at right angles to the strike of rock strata. This seems to indicate that these stream valleys have formed in zones of weakness such as fault and fracture systems, since these strata are relatively resistant to erosion. Other tributaries flow through strike valleys formed in less resistant shale units. Table 2 displays the flow characteristics of the streams affected by coal mining operations which are considered in the general area. The Crystal and Roaring Fork Rivers are similar in quality. Total suspended solids are less than 50 milligrams per liter for much of the year. Total dissolved solids are 200-500 milligrams per liter (mg/1) . Aith a pH slightly above neutral , heavy metals and trace elements in solution are low. All of these are indicators of good water quality. The Coal Creek Basin includes a 26.6 square mile watershed and consists of eight tributary streams. The Coal 3asin Hines affect six of these tributaries and a 10 square mile watershed area. Sediment loads within this basin are naturally hign. This is due to the steep terrain ana large volumes of runoff generated primarily by snowmelt. ',Dater quality is good with total dissolved solids concentration less than 500 mg/l .