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Forest Luke Trapper Mining Inc. October 6, 1998 Page 4 caused by varying precipitation amounts as indicated by an apparent inverse correlation between moving averages of TDS levels and precipitation in Figure 1. Surface water -Suitability for intended post-mining uses On-site. After mining is completed, Trapper's surface water will be used in the former mine permit area for watering livestock and wildlife. Trapper's surface water currently is suitable for those uses based on comparison with water quality suitability standards for domestic livestock issued by the State of Wyoming Department of Environmental Quality. (The Wyoming standazds aze used for comparison because Colorado has not issued suitability standards specifically for livestock or wildlife.) The suitability of Trapper's water for livestock and wildlife is expected to continue into the future based on long-term trends in Trapper's water quality data. 7. Off-site. Uses of surface water flowing from Trapper will have the same post-mining uses off-site as on-site. Based on the preceding discussion of the on-site suitability, it appeazs that Trapper's surface water currently is suitable for the offsite post-mining uses as well. This suitability is expected to continue into the future based on long-term trends in Trapper's water quality data. Ground water-Impacts from mining 8. Temporary depletion of ground water. Each of Trapper's pit excavations has partially depleted the water supply in aquifers surrounding each pit, at elevations above the deepest mining excavation. In each case the depletion has been temporary as the aquifers have eventually rechazged over several yeazs following pit backfilling. The original potentiometric surface in each unmined aquifer recovered a short distance outside each pit, but the spoil aquifer remains permanently depressed within each pit. The net effect on ground water quantities on Trapper and adjoining azeas appeazs to have been negligible. 9. Degradation of ground water quality. Mining appeazs to have degraded ground water quality in at least one location on Trapper as shown by a general increase in TDS levels in six monitoring wells on the mine (see Table 2). Sulfate makes up most of the TDS increase. The sulfate probably is dissolved from spoils as ground water flows through backfilled pits. The degradation would be expected to end when the sulfate source in the spoils is exhausted.