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Cover Factor "C" <br />For rangeland and pastureland, the "C" factor is directly related to the percent of the <br />ground covered by vegetation and the type of vegetation that is present. Subsurface <br />effects such as root mass can also be considered. The type of vegetation is important <br />because herbaceous plants with a live cover of 25% will protect the soil much better <br />than a site that contains an equal cover but where the cover is primarily comprised of <br />trees or shrubs. <br />Table 5 (from EPA 1977) shows the variation in "C" factors for varying range <br />conditions. From the 1987 study of the dryland pasture and irrigated pasture areas, the <br />cover breakdown is given below: <br />Pre -Mine Conditions <br />Irrigate Pasture - 1987 Cover Data <br />The irrigated pasture study area had 5 percent bare ground, 23 percent litter, 0.3 percent <br />annual forbs, 43 percent perennial grasses, and 29 percent perennial forbs for 72 <br />percent perennial live vegetation. Note: The irrigated pasture cover data was taken from <br />the Coal Mining Permit C -81 -008: 2005 -2006 Mid Term Review, which is based on the <br />1987 baseline survey. <br />0.3% Annual Forbs <br />43% Perennial Grasses <br />29% Perennial Forbs <br />23% Litter <br />Ground Cover (cover that contacts the surface) = Annual forbs + Perennial Grasses + <br />Perennial Forbs + Litter <br />Ground Cover = 95.3% <br />Canopy Cover = None <br />Canopy Cover = 0% <br />Using Table 5 and a canopy of 0% and the "G" canopy type, the C factor can be <br />determined. The best "C" value for the pre -mine irrigated pasture is 0.003. <br />SL -14 03DEC12.wpd 35 <br />