Laserfiche WebLink
Evaluation of Potential Subsidence Impacts of Longwall Mining in the Spruce Stomp Lease Area <br />to Aquatic Life and Water Supply <br />Typical soil types in the area around West Fork Terror Creek include clay, loam, clay loam, <br />stony to very stony clay and loam, and gravelly to very gravelly clay and loam. The mapped soil <br />units generally have low to moderate erosion potentials, with K factors ranging from 0.10 to <br />0.28. <br />During 2012 site visits, exposed soils were typically observed only in the vicinity of active or <br />recently active disturbances (e.g., landslide, roads, cattle paths). Additional bare soil was <br />observed in locations where the West Fork Terror Creek channel is not lined with cobble or <br />larger rocks and is downcutting into fine- grained soils. Based on observations of the area, soils <br />are typically well vegetated with 70 — 90 percent coverage. However, when soils are exposed due <br />to disturbance, they are prone to erosion. <br />4.1.5 Vegetation Communities /Ecosystems <br />The vegetation communities within the West Fork Terror Creek watershed are primarily <br />influenced by elevation, aspect and water availability. At the lower extent of the watershed, <br />upland hill slopes are largely vegetated with dense stands of Gambel oak, serviceberry, large <br />sagebrush, and upland grasses and forbs. Quaking aspen are common throughout the watershed, <br />but particularly on gently sloped terrain and at the outer fringe of riparian areas. Typical <br />associated understory plants within the aspen forest stands include Wood's rose, mountain <br />brome, American vetch and other upland and marginally hydrophytic grasses and forbs. <br />Dominant riparian vegetation includes willow and dogwood shrubs on lower gradient stream <br />banks and aspen or Douglas fir and Colorado blue spruce on north facing slopes. At the upper <br />end of the watershed, conifer woodland is present on steeper slopes with aspens and meadows <br />occupying the less steep terrain. <br />4.1.6 Climate <br />Based on data from the Western Regional Climate Center gage located in Paonia, the <br />approximate mean annual precipitation (NCDC 1981 — 2010 Monthly Normals) near the <br />Potential Project area is 15 inches. Dry year precipitation at this station can be approximately 33 <br />— 40 percent lower than the average (based on 1975 and 2002 total precipitation). Average <br />121- 014.000 Wright Water Engineers, Inc. Page 5 <br />January 2013 <br />