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West Elk Mine azeas consists of groundwater monitoring wells which are used to monitor and collect water level and water quality data. The nature of the groundwater resources at the mine is described in Section 2.04.7 and is not repeated herein. However, from the standpoint of determining probable hydrologic consequences, it is necessary to distinguish among the different groundwater regimes found at the site. These include the active and inactive groundwater zones. The active groundwater zone includes the near surface waters derived from rain and snowmelt stored in the near surface alluvium, colluvium and near surface bedrock formations (generally less than 500 feet in depth). The inactive zone exists in the bedrock formations and contains ancient groundwater residing in sandstone channels, within permeable discontinuous sand lenses, or within the damaged zones of fault and fracture systems. In general, the groundwater is associated with three hydrogeologic units. These include the alluvium, colluvium and bedrock. Each is described as follows: Alluvial Groundwater Found within the unconsolidated sediments adjacent to and underlying stream channels lazge enough to have deposited such materials. Within the permit area, there is little identifiable alluvium with the exception of Sylvester Gulch, the North Fork and the Dry Fork of Minnesota Creek. Impacts to alluvial groundwater are expected to be minimal because of its limited existence within the longwall angle of draw and the overburden separation between the mined underground coal resource and these surficial deposits. Colluvial Groundwater Found within the loose, unconsolidated soil material and/or rock fragments deposited by rainwash, sheetwash or continuous downslope creep. Many of the seeps and springs within the permit area aze a surface expression of the groundwater contained within the colluvium. Colluvial groundwater generally tends to be locally discontinuous, is dependent upon local snowmelt and precipitation events for recharge, and is usually within materials which have relatively little storage capacity. As such, interception of colluvial groundwater will generally produce flows which diminish over time as the water from storage is drained faster than the available recharge. Impacts to colluvial groundwater is normally considered to be deminimus since such groundwater is dependent upon factors which make this source of water unreliable for sustained use. Bedrock Groundwater Found within the consolidated rock with sufficient storage and permeability to retain and transmit subsurface water. The majority of the perennial seeps and springs within the permit azea aze probably supplied by bedrock groundwater. However, the discontinuous nature of the more permeable units and their relatively small storage capacity within the Mesaverde Formation at West Elk Mine, along with the seasonal variability of these spring flows, supports the conclusion that groundwater resources in the azea aze limited at best. Impacts to bedrock groundwater aze generally considered to be of little consequence because of its unreliability as a 2.05-205 Revised November 1004 PRIG