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As described above, relatively continuous sandstones in the lower Burro Canyon Formation yield small amounts of water to wells and are the source of several small springs and seeps in and around the permit area. Along with the rest of the stratigraphic section, this formation dips to the north at 2 to 3 degrees in the area. Discharge to the surface occurs at the seeps mentioned above. The formation does not outcrop within the permit area. Recharge to the Burro Canyon likely occurs well south of the permit area, and perhaps across bedding planes from adjacent finer-grained shaies of the Burro Canyon and Morrison Formations. Approximately 90 to 100 feet of interbedded shale, coal, and sandstone lenses separate the aquifer from the floor of the proposed mining pit, and there 1s no evidence that the aquifer is under sufficient head to cause leakage from the aquifer into the pit. As the Burro Canyon has insufficient head to cause upward migration of water, no loss of water is anticipated. Some infiltration of precipitation into the pit floor is likely, and by way of fractures some of this water could reach the Burro Canyon aquifer. However, infiltration would occur in such limited quantities that any water quality impacts would be limited to the immediate permit area. Sedimentary rocks of the Dakota Sandstone in the permit area, which will be exposed in the pit walls, probably do not contain measureable amounts of water, as none has been encountered in monitoring wells. Isolated lenses of perched water could be encountered by the pit, however they will not be sufficient to present either an operational or an environmental problem. Impacts to ailuvlal aquifers could occur in two ways, the diminution of recharge by detention of water in sediment ponds, and contamination by discharges from spoil springs. The relatively small maximum disturbed area of 257 acres will limit spoil spring development and pond water retention. Therefore, associated impacts should be minimal. Detention of runoff in the ponds will be minor, as the disturbed areas make up very small percentages of the watersheds 1n question. Therefore, alluvial impacts due to retention of recharge water should be negligible. The permit application states that spoil springs should not develop due to the low precipitation in the area (approximately 12 inches per year). Assuming 2 inches of infiltration per year (a conservative estimate based on 3 inches of infiltration reported at the Seneca II Mine in Routt County, which receives more precipitation than the Hamilton Mine area), approximately 43 'acre-feet of water per year of recharge to the spoil aquifer would occw'. If the aquifer reaches a steady state which includes disiparge from springs at the topographically lowest points of the pit-walls, this amount of recharge would translate into an average spol.l spring discharge of 26.6 GPM (0.06 CFS> for all sources within the permit area. It is likely that spoil spring development _19_