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reduction of base flow in nearby streams. As Fish Creek is located some distance down-gradient, and is most likely not incised into the Mesaverde Group, no depletion of base flow in the creek due to aquifer depletion is expected. Mining in the Twentymile Basin will not diminish the quantity of water within the alluvial aquifer system on a regional scale. Locally, surface mines may induce alluvial inflow, dependent upon proximity to the aquifer, while dewatering of underground mines may induce the alluvial aquifer to recharge the Middle Coal Group. These impacts will be localized and are dependent upon seasonal variations in the alluvial water levels. The cumulative impact to the Basin-wide alluvial aquifer system due to local dewatering will be negligible. It is apparent, therefore, that the potential effects of aquifer depletion are limited and that long-term impacts due to aquifer depletion will not be significant. As mining pits are reclaimed or as underground mines are abandoned, water from developing spoils aquifers will recharge the Middle Coal Group aquifers. Impacts to the aquifers will be due to the addition of these generally poor quality waters. The aquifers may exhibit increased concentrations of total dissolved solids, manganese and sulfate. This plume will follow the established flow pattern within the basin, to eventually discharge to either the surface water system in or adjacent to Twentymile Park or into the regional Sand Wash Basin. Due to the slow travel time within the aquifers, and to dispersion and dilution within the aquifers on a regional scale, long term effects of the dimunition of water quality will not contribute to or result in material damage to the adjoining environment. The quality of the Twentymile Sandstone may be potentially impacted near the Seneca II Mine site. This is because Bond and Cow Camp Creeks bissect a portion of the recharge area of this regional aquifer as they exit the permit area. The potential impact would occur when spoils aquifer discharges contribute the majority of flow to these drainages. On a regional scale, the cumulative impact to the quality of the Twentymile Sandstone will be negligible due to the insignificantly small area of the formation which is bissected and potentially recharged by these streams. It is not thought that, due to the thick sequence of relatively impermeable material underlying the Twentymile Sandstone, other mines in the basin will impact this unit. The quality of the alluvial aquifer system will be degraded due to coal mining activities. This impact is due to the partial recharge of the alluvial aquifers from spoils aquifer discharges. Spoils aquifer discharges, combined with natural runoff, will recharge the alluvial aquifer during the spring. During the growing season (June through -30-