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• Specific Conductivity/Total Dissolved Solids Specific conductivity (Figure 23) and total dissolved solids (Figure 29) values for the three alluvial wells have remained fairly constant over the majority of the period of record. While Conductivity and TDS values at sites TR-3 and TR-9 are consistent with values obtained during the baseline studies, these parameters and several others have elevated rapidly and remained elevated at TR-1.5 since 1995. The source of the elevated values is not readily identifiable. A few factors which may have contributed to the elevated levels were mentioned in the 1996 Report (i.e., inundation of the area in late spring of 1995 and the laying of telephone cable immediately upstream of the area during the summer of 1995). If the elevated Conductivity and TDS levels were primarily the result of the previously mentioned activities, the concentrations should have returned to more historic levels during the 1996 monitoring period. However, the concentrations have remained elevated, and therefore it appears that the alluvium in this area is reflecting a plume of upstream alluvial water containing high levels of TDS, possibly from an old abandoned underground mine up the Little Trout Creek drainage. This conclusion is based partially on the similarity of the water quality between TR-1.5 and WR-1. As • previously discussed in the surface water section, data taken between October 1990 and August 1992 is believed to be invalid due to instrument errors. Conductivity and TDS values in Well WR-1 have progressed from elevated levels each spring to lower concentrations in the fall for the past several years. This phenomenon is caused by infiltration of snowmelt water leaching various minerals within the unsaturated zone of reclaimed spoil. As the enriched flow is released over the course of the summer, the conductivity values lessen to that of the stagnant saturated zone. The levels of Conductivity and TDS decreased significantly in late 1995 probably resulting from a drier than normal summer. In 1996, the trend appears more normal reflecting precipitation and infiltration patterns as in previous years. Calcium/Magnesium/Sodium Calcium (Figure 25) is the major cation found in all of the wells with concentrations of sodium (Figure 26) and magnesium (Figure 27) occurring in lesser quantities. TR-1.5 generally contained the lowest concentrations of cations with a slight increase occurring downstream at TR-3 and TR-9 for the majority of the record. However, elevated levels of these parameters at TR-1.5 began to occur in • 1995 consistent with the elevated Conductivity and TDS levels previously mentioned. 31