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-18- A significant factor with respect to hydrologic consequences is related to the quantity of ground and surface water in the permit and adjacent areas. Surface water flow eaithin the drainages which will be affected is sporadic and occurs primarily in response to periods of snocamelt or individual rainfall events. Some of the flow will be removed from Hayden Gulch as a result of containment within the sediment control system and will be consumed by the operation (dust suppression). Surface water in Dry Creek and Dowden Gulch will also be impacted by the operation. The area removed from the Dry Creek drainage as a result of a diversion around the spoil pile is insignificant with respect to the total drainage area of the Dry Creek basin. Flow in Dowden Gulch will not be impacted until the next permit term. Prior to approval of the extension of mining into Dowden Gulch, the ap?licant will be required to submit sufficient information to determine the effect on surface flow in Dowden Gulch. The loadout occupies a relatively small portion of the Dry Creek drainage. All runoff will be contained within the sediment control system and will be treated prior to release. The effect on surface water quantity in Dr,' Creek as a result of the operations at the loadout is negligible. The effect of the operation on surface water quantity will be greatest during the mining and reclamation stages. Once the areas are reclaimed, the sedimenC ponds will be retained as stock ponds. All other aspects of the surface water hydrology will return to pre-mining conditions (i.e., post-mi~.~ing topography and drainage, etc.). During the operation, a few water-bearing strata will be impacted. Most of these strata are within the mine zone. Some springs origina[:ing in localized sandstones may also be impacted. In many instances, the strata within the mine zone were dry according to static water level measurements (p. 24, Section 4, Appendix R, Volume VII). Measurements of discharge from the springs indicate that water yield is low from these strata. Ptost of the ground water usage in the surrounding area consists of registered wells that are along strike or up dip of the mine and which, in many cases, are hydrologically isol~sted from the mine zone. The only well downdip of the mine is too far from the disturbance to be affected. Degradation of surface water quality will he minimal during the operation. Run- off from all disturbances will be contained within a sediment control system. Plater quality will be periodically monitored upstream and do~onstream of the sites to determine impacts of the operation. Any discharges Erom the sediment control system will have to meet minimum quality standards. !successful reclama- tion of the disturbance will nearly restore baseline conditions. The operation will probably affect the quality of water in the water-bearing strata within the mine zone. Once the pit is backfilled, water leaching through the spoil may pick up additional concentrations of constituents from the over- burden. This water will eventually find its way into water-bearing strata in the mine zone.