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3.2 SULFATE Figure B-9 presents the sulfate concentrations for QR wells GD-2, GD-3 and GE-1. Sulfate in backfill well GD-3 decreased significantly in 1996 and then increased to a similaz peak level by 2000. Sulfate concentrations in well GD-3 have been fairly steady at this peak concentration for the last six years. This indicates that the sulfate fluctuations in the backfill aquifer may be larger than the native QR aquifer. Future monitoring of this well will define whether sulfate concentrations will decrease in the backfill aquifer during wet cycles and increase to a maximum during a dry cycle. Concentrations in well GD-2 have overall gradually increased the last few yeazs. The sulfate concentrations in well GD-2 show that the QR aquifer near well GD-2 has not been significantly affected by the upgradient backfill aquifer water quality. Sulfate concentrations had declined in well GE-1 in 1999 aRer a peak neaz 400 mg/1 but increased in 2003 and 2004 and then declined in 2005. The recent low concentrations in well GE-1 may be caused by lower concentrations in the backfill aquifer resulting in a lower input of sulfate water. Figure B-10 also presents sulfate concentrations for QR wells. This figure shows that sulfate concentrations in backfill well GF-11, which is upgradient of QR well GF-6, were lower in 2005 showing a decline from the historic peak in 2001. Future monitoring is needed to define the maximum sulfate concentration in this backfill aquifer which may have been defined in 2001 and 2002. The sulfate concentrations gradually increased in well GF-6, downgradient of well GF-11. Sulfate concentrations for the last few years had gradually increased in QR well GP-5 while steady levels were observed in 2005. A gradual decline in sulfate was observed in 2005 in well GP-6. As expected, the sulfate concentrations are greater in downgradient well GP-5 and its changes aze well within natural variations. • Trapper Mining Company 3-5 2005 Annual Report