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various times of the year, recharge the associated alluvial/colluvial aquifers with the sediment pond discharge. These sediment pond discharges are typically higher in dissolved constituents than the naturally occurring runoff from the undisturbed site. As the alluvial/colluvial water quality closely mirrors the quality of the stream, a degradation (ie: increase in TDS) is observable in alluvial monitoring wells down-gradient of the mine site. In portions of Little Grassy Creek drainage which are in contact with previously disturbed lands, an increase in TDS over baseline conditions is observable. This is due to the addition of spoils water, which has been discharged from backfilled portions of the mine site, to the alluvial system. As previously discussed, backfilled mining pits will re saturate along the base of the mined coal (top of the underburden) to an elevation equal to that of the lowest point (topographically) of the downslope highwall. When the elevation head of the spoils aquifer exceeds the elevation of the lowest point of the downslope highwall, a spoils spring will develop at that location. These springs discharge water which is typically high in TDS, sulfate, manganese and sodium. It is thought that the spoils discharge will vary with time, dependent upon local climatologic and hydrogeologic conditions. The quality of the discharges is expected to improve with time, however, the length of time required prior to measuring acceptable (i. e. approximating baseline conditions) water quality, is not currently known. When Peabody Coal Company can demonstrate that the reclaimed lands meet the phase II bond release criteria, the sediment ponds, excepting the Wadge Impoundment (NPDES 002), which is an approved permanent impoundment, will be removed from the site. At that point in time, it is assumed that the majority of baseflow to Cow Camp, Bond and Grassy Creeks will be contributed by spoil aquifer discharges to the surface system. In the Grassy Creek Drainage, the quantity and quality of the flows will be similar to present conditions. All of the spoil spring discharges issuing into the Grassy Creek drainage will pass through the Wadge Impoundment, a permanent structure. Dilution and mixing within the impoundment will limit the concentration of dissolved solids discharged to the alluvial system. As mining continues in this drainage, some increase in dissolved constituents is expected. Data collected at NPDES sites 002 and 003, which discharge disturbed area drainage into Grassy Creek, indicate that there has been an increase in TDS, based on monthly average concentration (June through September) on a yearly basis for the years 1982 through 1986. It should be noted, however, that the rate of increase, based on monthly average TDS concentration on a yearly basis, appears to have stabilized during this period. Therefore, it is not expected that the quality of the effluent will further degrade the alluvial water quality in the Grassy Creek Drainage. In the Cow Camp and Bond Creek drainages, Wadge spoils aquifer discharges will contribute flow to these tributary creeks and eventually to Fish Creek. During the months of June and July, Cow Camp Creek and Bond Creek sustain flow their entire length to Fish Creek. During this period, each creek contributes water to the associated alluvial aquifers. The spoils spring discharges are sufficiently diluted by snowmelt runoff to preclude degradation to the quality -24-