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-38- Probable Hydrologic Consequences - 4'urface Water (Cont'd) The surface disturbedarea associated with the Blue Ribbon Pfine is approximately 20 acres, or about O.Io of the drainage area of Hubbard Creek, excluding those areas of upstream diversion. The actual production of water from the surface affected area of the Blue Ribbon Mine will be somewhat less than O.lo of the flow in Hubbard Creek due to the direct relationship of water yield to elevation. Therefore, assuming that all runoff water from the mine is lost through evapor- ation in sediment ponds (worst case), a loss of less than 0.1% of Hubbard Creek yields is expected. A consequence of the use of sediment ponds for treatment of mine site runoff is the increased concentration of dissolved solids in waters discharged to the receiving streams. It is anticipated that, due to the high dilution ratio of Hubbard Creek to the outflow rates of ponds at the Blue Ribbon Mine, discharges will only minimally increase total dissolved solids (TDS) in Hubbard Creek. Since the mine workings are above the Level of Hubbard Creek, the mine presently does not experience any inflows which can be directly related to the water flowing in Hubbard Creek. As mining progresses to the north and west, mine workings will eventually be located below the Ieve1 of the streambed and alluvium of Hubbard Creek. The area of the mine which will eventually be located beneath the level of the Hubbard Creek alluvium appears to be approximately 5 acres and is more than 2,000', horizontally, from the Hubbard Creek alluvium. The mine may encounter faults and fractures in this northern area. If faults and fractures are in contact with streambed or alluvium, they would, in turn, provide conduits through which stream water may be routed into the mine workings. The depletion in Hubbard Creek due to mine inflows would not be significant; 1) since the area of the mine below the Level of Hubbard Creek is small, and 2) since the water made in the mine would most Likely be consumed within the mine or humped to the surface. The use of mine inflow water would, in turn, reduce the amount of water no[v being pumped from the well in the Hubbard Creek alluvium. The net depletion of the quantity of water in Hubbard Creek during mining would be zero. However, following mining, there is a possibility that water tributary to Hubbard Creek will continue to be depleted until the mine workings and all dewatering faults, fractures and rock strata below the creek level are filled or recharged. The amount of water involved in the filling of the workings and affected strata will be small, given the limited area of mining below the level of the creek. Subsidence fractures which extend to the surface may impact overland surface flow and stream flows in the small ephemeral drainage above the mine workings. This impact to surface [eater is expected to be negligible due to the small total area of the mine, the steep slopes (60% slope, or 30 degrees) and the steep stream gradients encountered in the permit area. The steepness of the slopes and stream- beds [would favor runoff over infiltration even with subsidence fractures inter- cepting the surface. Blue Ribbon Coal Company has conducted a spring survey of the permit area. One spring [vas Located within the permit area. This spring is located below the mine bench and discharges from rock strata which are stratigraphically below the "E" seam. The Blue Ribbon mining operation should have no effect on the quantity and quality of flow in this spring.