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GD-2 has not been significantly affected by the upgradient backfill aquifer water quality. Figure B- <br />ncentrations for additional R wells. This fi e shows that sulfate <br />9 also presents sulfate co Q ~' <br />concentrations in backfill well GF-11, which is upgradient of QR well GF-6, were lower in 2006 <br />and 2007 showing a decline from the historic peak in 2001. Future monitoring is needed to define <br />the maximum sulfate concentration in this backfill aquifer which may have been defined in 2001 <br />and 2002. The sulfate concentrations gradually increased in well GF-6, downgradient of well GF- <br />11. Sulfate concentrations for the last few years have overall gradually increased in QR well GP-5. <br />Figure B-10 presents the sulfate concentrations for KLM aquifer wells GP-2, GP-4 and GP- <br />8. Sulfate concentrations in eastern well GP-2 have varied significantly but declined in 2007 after <br />recently being steady. These changes are within the natural historic range defined at this well prior <br />to mining in this area. Overall steady sulfate concentrations in well GP-4 have existed the last few <br />years with the 2007 level showing a decline. Sulfate concentrations in well GP-8 have stayed <br />steady and small as mining approaches this area. <br />Sulfate concentrations for the HI aquifer wells are presented in Figures B-11 and B-12. The <br />sulfate concentration in wells in the HI aquifer wells in Figure B-11 are fairly similaz except for the <br />values in backfill well GF-7, which are substantially greater than those in downgradient well GF-4. <br />A gradual decrease in sulfate concentrations has been observed in well GF-4 after a very gradual <br />increase for several years. These small variations are well within the natural variation of sulfate <br />concentrations in the HI aquifer but could be defining the very small effects of the backfill aquifer <br />upgradient. Sulfate concentrations in bacl~ill well GF-7 overall were steady in 2007. The water <br />levels for the last few years have been fairly similaz in well GF-7, indicating that these changes aze <br />not due to new backfill being saturated but likely due to variations in rechazge. Sulfate <br />concentrations have stayed low and steady in backfill well GF-5. These small changes may be <br />Trapper Mining Company 3-5 <br />2007 Annual Report <br />