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6.0 OBSERVED IMPACTS ON THE HYDROLOGIC SYSTEMS <br />OF THE TRAPPER MINE <br />6.1 GROUND WATER <br />Water -level changes in the last few years for the QR aquifer are mainly due to natural <br />variations in the recharge rate. Water -level changes were observed in QR aquifer wells GD -2 and <br />GF -6, along with associated backfill wells GD -3 and GF -11. Water levels in wells GD -2 and GD -3 <br />declined in 2006 and these declines are thought to be due to some deep exploration drilling in this <br />area. Wells GD -2 and GF -6 are fairly close to mined areas but a slight increase in water levels were <br />observed in wells GF -6 and GF -11 in 2006 while a significant decline was observed in wells GD -2 <br />and GD -3. Additional monitoring with time is needed to determine the significance of the decline <br />in wells GD -2 and GD -3. The responses in wells GF -6 and GF -11 indicated that the present water <br />level gradually increased due to the increase in precipitation in 2005 and 2006. These wells are <br />located near the downgradient toe of D and E pits and/or at the interface of upgradient backfill and <br />the downgradient native QR aquifer. These well locations seem to be relating to changes in <br />precipitation with very little lag in time. <br />Upgradient mining can cause water -level rises in wells downgradient of the mining by <br />allowing ground water to flow to the downgradient end of mine quicker. The backfill aquifers are <br />generally more permeable than the native aquifer which also allows ground water to flow faster <br />through the backfill material resulting in more water in the aquifer at this location. The input of <br />additional water to the native aquifer at the north end (toe) of the mine has decreased the effects <br />mine dewatering has had on water levels in this portion of the aquifer. Water levels in wells GF -6 <br />and GF -11 are thought to be at or above the baseline levels for this reason. The slightly higher <br />water levels in well GD -2 in 1998 than those observed in 1986 after six wet years indicates the <br />Trapper Mining Company 6-1 <br />2006 Annual Report <br />