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neutral. The same major constituents contribute to the make-up of the Second White <br />Sandstone water as they do for the Third White Sandstone. <br />Lewis Shale <br />The Lewis Shale aquifer is monitored in Pyeatt Gulch at well P-3. The TDS of <br />water from this well is presented in Figure 2.7-28q and shows that, as expected, the <br />TDS is higher in this. aquifer and varies over a larger range. The Lewis Shale is <br />expected to contain more available salts for dissolution than the other units. The <br />pH of the Lewis Shale water has stayed fairly close to neutral. Sulfate and <br />bicarbonate concentrations make up most of the anion concentration, but chloride is <br />much higher in the Lewis Shale water. Calcium, sodium and magnesium equally are the <br />• major cations. <br />0 <br />Alluvial Aquifers <br />Well P-1 monitors the Pyeatt alluvial aquifer in the eastern portion of the <br />Trapper permit, while wells GC -3 and COY have been used to monitor the Flume <br />alluvial aquifer. The TDS of the Pyeatt alluvial aquifer at well P-1 has varied <br />greatly also, probably depending on the percentage of the water contributed from the <br />Lewis Shale. TDS prior to 1984 was above 2000 mg/1, but dropped significantly in <br />1984 after an increase in the baseflow in the Pyeatt Gulch (see Figure 2.7-28r). <br />Concentrations have increased during the last three years. <br />The TDS in Flume alluvium has not varied as much as the Pyeatt alluvial TDS <br />and is approximately 1400 mg/1 presently at both wells GC -3 and COY. Figure 2.7-28s <br />2-520gq LJE® <br />FFR 1 '� '0) 7 <br />