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<br />• <br />Mine discharge generally improves the conductivity of East Salt Creek surface waters. <br />In 2005 there was a slight increase, but the 0.2% increase is nearly negligible as the <br />increase is only 4 micromhos/cm. The mass balance for the irrigation season is <br />calculated by multiplying the flow*conductivity and dividing by the sum of flow. See <br />Appendix N, Tables N-3 through N-7 for yearly mass-balances. (Mass balance is for <br />the irrigation season only). <br />PHC East Salt (2003-2007) Creek SW-1 <br /> Conductivity <br />Irrigation <br />Season Increase Decrease <br />2003 -5.1 <br />2004 -18.4% <br />2005 0.24% <br />2006 -7.09% <br />2007 -9.24% <br />5-Year mass <br />balance -8.2% <br />4-5 <br />The East Salt Creek Alluvium is recognized as an alluvial valley floor. Data gathered <br />over the last several water years for GW-3 demonstrates the mine discharge has not <br />had a negative impact on the alluvial groundwater. As shown below, nearly all <br />conductivity data recorded falls between the GW-3 baseline and the mine water <br />average conductivity reference line. Since nearly all the data points fall below the <br />baseline for GW-3, it is not likely the mine discharge has increased the conductivity of <br />the alluvial groundwater. The mine discharge could only lower the conductivity of the <br />alluvial groundwater since the conductivity of the mine water is less than the <br />conductivity of GW-3. The situation is the same at all of the groundwater monitoring <br />wells. The baseline conductivity of all of the GW wells exceeds the average <br />conductivity of the water discharged from the mine. Therefore, the conductivity of the <br />alluvial groundwater can only be improved by the mine water discharge. <br />TR-16 <br />M`-Volume 1 <br />(Rev 05/08) <br />