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The alluvial ground water in Johnson Gulch has shown TDS variations with time <br /> with a generally lower TDS in 1988, 1989 and 1990 and a higher value in 1992 through <br /> 1998. These TDS values and variations are very similar to the natural values and <br /> variations observed in Flume Gulch alluvial well, COY. <br /> Flume Gulch has two alluvial monitoring wells, GC-3 and COY. TDS concentrations <br /> have been fairly steady in well GC-3 with a minor decrease in 1996 through 1998, which is <br /> likely due to an increased rate of recharge. The TDS concentrations in the COY well show <br /> that the Johnson alluvial TDS concentrations are within natural alluvial concentrations in <br /> this area. <br /> 3.2 SULFATE <br /> Sulfate concentrations for the Twenty Mile Sandstone aquifer and the U aquifer are <br /> presented in Figure B-10. This plot shows a significant amount of variation in the sulfate <br /> concentrations in Twenty Mile Sandstone wells with no long-term trend. This deep aquifer <br /> would be expected to respond slowly to better recharge years. Figure B-10 also presents <br /> the plot of U aquifer well GF-2. The 1997 and 1998 values indicate that the 1996 value for <br /> well GF-2 is an outlier. <br /> Figure B-11 presents the sulfate concentrations for QR wells GD-2, GD-3 and GE-1. <br /> Sulfate in backfill well GD-3 decreased significantly in 1996 and increased in 1997 and <br /> 1998. This indicates that the fluctuation in the backfill aquifer may be larger than the <br /> native QR aquifer. Future monitoring of this well will define whether a larger fluctuation <br /> exists In this backfill aquifer. Concentrations in well GD-2 have been fairly steady with a <br /> • slight increase in average sulfate concentrations over the last few years versus <br /> 3-5 <br />