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• 2.1 GROUND WATER-LEVEL CHANGES <br /> 2.1.1 SUMMARY <br /> Water-level changes in wells GD2 and GF6 are thought to be <br /> mainly attributed to natural variation in recharge to the OR <br /> aquifer. Some of the water-level changes could be a result of <br /> mining. Figure 2-1, Precipitation at the Trapper Mine, compares <br /> well to water-level declines in these wells. Water-level <br /> responses in wells GD2 and GFb are very similar to those in wells <br /> GPI and GPS, which are OR aquifer wells that are distant to any <br /> active mining and reflect these natural variations. Water-level <br /> changes in OR well, GA1, have responded similarly, but some of <br /> the change in this well is likely to be caused by mining. <br /> Upgradient mining can cause water-level rises in wells <br />• do <br />di <br />f th <br />t <br />i <br />i <br />b <br />ll <br />i <br />d <br />t <br />t <br />fl <br />t <br /> wngra <br />en <br />ow <br />ng groun <br />wa <br />ow <br />o <br />e m <br />n <br />ng <br />y a <br />er <br />o <br />o <br /> the downgradient end of mining quicker. Also, the backfill <br /> aquifers are more permeable than the native aquifer which also <br /> allows ground water to flow faster through the backfill material <br /> resulting in more water to the aquifer at this location. The <br /> input of additional water to the native aquifer at the north end <br /> of the mining has decreased the affects mine dewatering has had <br /> on water levels in this portion of the aquifers. <br /> Levels in the backfill areas are depressed and are likely <br /> not to ever recover to pre-mine levels. Map 2-1 shows that the <br /> levels in the backfill and downgradient aquifers are close. Well <br /> pairs GD3-GD2 and GF11-GF6 present water levels that are very <br />• close in water-level elevation for the backfill and downgradient <br /> QR aquifer well. <br />2-2 <br />