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6.0 OBSERVED IMPACTS ON THE HYDROLOGIC SYSTEMS OF THE TRAPPER MINE <br /> 6.1 GRUDND WATER <br /> Water-quality changes in the last few years for the 9R aquifer <br /> are mainly due to natural variations in the recharee rate. Water- <br /> level changes in 9R aquifer wells. GD2 and GF6, which are close to <br /> ar_tive mining may have been sliehtly influenced by mining <br /> activities, but are mainl.v due to natural changes. Water-level <br /> changes in these two wells are similar to those from ra,R wells east <br /> of the mining activities. Water-level changes in 9R well GA1 have <br /> responded similarly to well GP1. but some of the GA1 change is <br /> likely due to mining. <br />• Upgradient mining can cause water-level rises in wells <br /> downgradient of the mining by allowing ground water to flow to the <br /> downgradient end of mining quicker. Also, the backfill aquifers <br /> are more permeable than the native aquifer which also allows ground <br /> water to flow faster through the backfill material resulting in <br /> more water in the aquifer at this location. The input of <br /> additional water to the native aquifer at the north end (toe) of <br /> the mining has decreased the effects mine dewatering has had on <br /> water levels in this portion of the aquifer. <br /> The water-level changes for the HI aquifer have also been <br /> influenced by variations in recharge during the last few ye.srs. <br /> The mining upgradient of HI wells GB5 and GFs. whir_h ocr_urred <br /> several years ago, has been allowing the water levels in the HI <br />• <br /> aquifer to rise. Some of this rise could be above pre-mine levels <br />6-1 <br />