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The probable hydrologic consequences of mining at the Bourg site were evaluated in the original permit application. The consequences relative to surface water were (l) that the runoff from the mine area would be increased and (2) that a portion of the runoff would be stored in sedimentation ponds and lost to evaporation. At this point, ten years after reclamation, neither of these consequences are realized. The original analysis pointed out that the Bourg property makes up only 14% of the total azea of the Mann Draw drainage area. As such, runoff would need to be significantly enhanced to cause negative impacts. At this time, the 160 acres of the Bourg property are the most densely vegetated land in that drainage azea. So despite the fact that a gravel pad and several roads remain, it is doubtful that the runoff from the Bourg property is even as great as it was before mining. Visual inspection confirms no evidence of high runoff. The findings indicate that there are no detrimental surface water impacts from the reclaimed Bourg Strip Mine. G. Probable Hydrologic Consequences of Mining on Groundwater Groundwater has been monitored to observe the effects of mining in the alluvial aquifer of Mann Draw. The geologic structure and consequent hydrologic setting of the Bourg permit area subsurface made this a logical approach. The Bourg Mine is underlain by a Northwest-plunging syncline. The Coalmont formation in the core of the syncline contains sandstone and siltstone units with some water-carrying capacity. Water infiltrating the spoils which replaced the Coalmont and the Sudduth coal will either recharge the bedrock units of the Coalmont formation or flow downgradient through Mann Draw alluvium toward the Canadian River. Recharge of the Coalmont units probably resumed after reclamation, but there are no wells documented within that formation to the northwest of the mine. So the principle potential for groundwater impact is in the Mann Draw alluvium. Water quality has been measured in the alluvium both upgradient (upstream of the impacts of mining) and downgradient of the reclaimed mine area. As would be expected, there has been some degradation of water quality at the downstream site. Sodium, chloride, sulfate, and total dissolved solids still show higher levels downgradient of the mine, and pH is increased. However, the concentrations of these constituents have stabilized or even decreased over the last 5 years. TDS, for example, has decreased from a high near 1700 mg/1 in the early 1990s to values from 1200 mg/1 to less than 1000 mg/1 in 1997. Upgradient water chemistry is much more variable that the water leaving the site. In fact, the upgradient well was dry for most of the sampling events in the 1990s, and has held measurable water again only the last two years. The hydrochemistry of the upgradient water undoubtedly fluctuates with the volume of water flowing through the system. Bourg Strip Mine. C-81-021 20 August 4, 1998