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level of less than 500 mg/l, but is characterized as very hard. It is suitable for livestock and <br />irrigation, however, flow is generally inadequate for irrigation. <br />Dry Creek water quality is categorized as brackish, since TDS averages greater than 1000 mg/1(1048 <br />mg/1) near the confluence with Hubberson Gulch. Water quality degrades further downstream. With <br />an average pH of 8.3, the water is slightly alkaline. Hardness averages 796 mg/1, and is considered <br />very hard. <br />Climate <br />The average annual precipitation at the mine site is approximately 16 inches. The precipitation is <br />consistent throughout the year with no significant dry periods. The mean annual temperature is 42°F. <br />The average maximum and minimum temperatures are 66°F and 17°F respectively. Regionally, <br />wind directions run east-west following the Yampa River Valley. More localized wind patterns <br />trend along the side valleys. <br />Land I ke, <br />The current and historic land use of the area in which the operation is located is grazing land for <br />livestock and habitat for wildlife. Regional land use patterns are oriented in three relatively distinct <br />bands. Irrigated cropland is closely associated with the floodplain of the Yampa River. To the south, <br />non-irrigated crops are grown on the sloping upland surfaces. The area nearest the mining operation <br />is mostly hilly and mountainous terrain and used primarily as rangeland for livestock grazing and <br />wildlife habitat. <br />Soils <br />The soils found within and adjacent to the mine plan area are typical of soils found in the cold, <br />semi-arid regions of the Western United States. The soils are generally moderately deep (20 to 40 <br />inches) to shallow (10 to 20 inches) and have developed in weathered, interbedded fine sandstone, <br />siltstone, and shale, and in local slope wash and colluvium. Most of the soils are Borollic Vertic <br />Camborthids, Lithic Cryoborolls, and Pachic Cryoborolls. <br />Most of the soil types found in the mine plan area contain at least six inches of suitable topsoil <br />material. The best sources of topsoil material are the Splitro silt loam, the Winevada Loam, and the <br />Cochetopa Loam, which comprise significant portions of the area to be disturbed. Salvage depths <br />vary from 6 to 64 inches, resulting in an overall average soil replacement depth of 1.3 feet (15.6 <br />inches) over regraded areas in the original permit area. Average soil replacement thickness in the <br />South Extension area is 1.1 feet (13.2 inches), with the exception of aspen establishment areas, <br />where average replacement thickness is 4 feet, and upland shrub establishment areas topsoiled in <br />2006, where average replacement thickness is 0.6 feet (7.2 inches). <br />Vegetation <br />Seneca II-W Findings Document 11 C1982057 <br />Permit Renewal No. 5 December 9, 2010