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-23- Potential Effects on Surface Water Quality General Area Based on the hydrologic balance calculations for the drainages in the general area and the fact that all runoff from the mine area is to be either diverted around the mine or retained in sedimentation ponds for a maximum of 36 hours, no change will occur. Since the area to be mined is a fraction of the total watershed areas, the general area will not be affected at-a11. Permit Area No significant effects to the hydrologic balance of Taylor, Wilson, or Good Spring Creeks will occur as a result of mining. Bare spoils and areas freshly stripped of topsoil and vegetation will exhibit increased runoff as bare soils tend to have lower infiltration rates than soils protected by a vegetative cover. This short term increases runoff from areas in the process of being minim and from areas being reclaimed is compensatory. Runoff from the areas being mined flows to the bottom of the pit which has no outlet. Zt then evaporates, infiltrates or is otherwise lost to the surface drainage system, Increased runoff from areas regraded but not yet vegetated flows through constructed channels to a detention pond and eventually enters the natural drainage system. It is estimated that the combines total area that is being mined or reclaimed at any one time will not be more than 279 acres. The net effect of the runoff retained in the pit and the increases runoff from disturbed areas on the hydrologic balance is considered compensating or negligible and involves a small portion of the total area being mined. Runoff detained in the detention ponds that exceeds the primary spillway capacity will be hi~.Zd for 24 hours. Water stored below the primary spillways will be released from time to time in accordance with the NPDES permit. These ponds will only interrupt flow resulting from precipitation falling directly on the mine and associated areas. As discusses below, this flow is a fraction of the total flow in all of the drainages ands therefore, is not significant. Colowyo's reclamation plan includes replacing all topsoil, reconstructing all major drainage channels and reestablishing the vegetative cover. As a result, the effects of mining on interception, evaporation, surface and bank storage and most other abstractions from precipitation will be negligible or compensatory. Infiltration rates may increase due to the stripping, stockpiling, handling, and spreading of surface soils. These activities would add to the effects of the reclamation practices used by Colowyo Coal Company such as mulching, furrowing; anti revegetation.