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downstream. With an average pH of 8.3, the water is slightly alkaline. Hardness averages 796 mg/1, and is considered very hard. Climate The average annual precipitation at the mine site is approximately 16 inches. The precipitation is consistent throughout the year with no significant dry periods. The mean annual temperature is 42°F. The average maximum and minimum temperatures are 66°F and 17°F respectively. Regionally, wind directions run east-west following the Yampa River Valley. More localized wind patterns trend along the side valleys. Land Use The current and historic land use of the area in which the operation is located is grazing land for livestock and habitat for wildlife. Regional land use patterns are oriented in three relatively distinct bands. Irrigated cropland is closely associated with the floodplain of the Yampa River. To the south, non-irrigated crops are grown on the sloping upland surfaces. The area nearest the mining operation is mostly hilly and mountainous terrain and used primarily as rangeland for livestock grazing and wildlife habitat. Soils The soils found within and adjacent to the mine plan area are typical of soils found in the cold, semi-arid regions of the Western United States. The soils are generally moderately deep (20 to 40 inches) to shallow (10 to 20 inches) and have developed in weathered, interbedded fine sandstone, siltstone, and shale, and in local slope wash and colluvium. Most of the soils are Borollic Vertic Camborthids, Lithic Cryoborolls, and Pachic Cryoborolls. Most of the soil types found in the mine plan area contain at least six inches of suitable topsoil material. The best sources of topsoil material are the Splitro silt loam, the Winevada Loam, and the Cochetopa Loam which comprise significant portions of the area to be disturbed. Salvage depths vary from 6 to 64 inches, resulting in an overall soil replacement depth of 15 inches over regraded areas. The topsoil replacement plan was modified by PR-3, to allow for variation in replacement thickness in order to enhance vegetative diversity. Four intermingled replacement zones are depicted on Exhibit 21-1 for areas to be topsoiled between 2001 and 2012 in the South Mining Block and the South Extension Area. Replacement zones include 1 foot, 1.7 foot, 2.5 foot, and 4 foot topsoil replacement thicknesses. Ve eg tation Vegetation in the vicinity of the mine is characterized by three vegetative types; mixed brush, sagebrush grassland, and aspen. Aspen forest is the dominant vegetation type within the PR- 3 disturbance expansion area. Land use in the mine area is undeveloped rangeland, with a Seneca II-W Findings Document 10 June 15, 2001 Permit Renewal No. 3 May 2, 2003