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natural because upgradient mining has occurred only during the last <br />couple of years. • <br />Significant changes in conductivity conce.ltrations have been <br />observed in the alluvial wells GC3, P1, J1 and (:oy, The changes in <br />the Flume alluvial wells has to be natural, while some of the <br />changes in J1 water could be due to mining. T'ae conductivity for <br />J1 increased during 1991. The changes in Pyeatt alluvial well P1 <br />are tk~ought to be natural because they are similar to those <br />observed prior to mining in this drainage. <br />The pH values for all of the Trapper wells are within the <br />range of natural values for these aquifers. The pH values for the <br />four backfill wells is within the range observed in the other <br />aquifers. Radium-226 concentrations at Trappe:^ Mine were all low <br />in 1991. <br />6.2 SURFAC$ WATER <br />The average flows for the surface water sites at Trapper Mine <br />were depressed in 1991 compared to average flow; observed in 1987. <br />Overall precipitation also decreased in 1991. No failures or <br />monitoring site problems were encountered during 1991. <br />These low flows were responsible for poor flow versus sediment <br />relationships and rising TDS values during 1991. Other chemical <br />constituents analyzed from samples collected frcm the surface water <br />sites showed little change. Monitoring data indicates that Trapper <br />Mine sediment control structures prevented any impacts on the <br />surface water systems downgradient of the mine in 1991. <br />• <br />6-4 <br />