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E <br />elevated above the EWI at down gradient alluvial well 21 -5 during the quarter. <br />The sample, collected in June 2012, was reported with a value for dissolved <br />sodium of 503 mg /L. The calculated EWI for this constituent at this monitoring <br />point is 498 mg /L, a difference of 5 mg /L. The previous sample from the March <br />2013 sample campaign was 26 mg /L above the EWI so the difference is <br />significantly reduced. The baseline mean value for dissolved sodium for this well <br />is 443 mg /L computed from 15 baseline samples. The maximum value for <br />dissolved sodium observed in the baseline program was 456 mg /L. The <br />operational mean value determined from 86 samples is 472 mg /L. The value of <br />dissolved sodium at alluvial well 21 -5 has exceeded the calculated EWI eleven <br />times previously in the operational period of record. These twelve points are <br />summarized in the following table along with their respective sample dates: <br />Sample Date <br />Alluvial Well 21 -5 <br />Dissolved Sodium (mg /L) <br />Early Warning Indicator <br />498 <br />April 2, 2002 <br />505 <br />January 19, 2004 <br />500 <br />June 21, 2004 <br />518 <br />September 10, 2004 <br />520 <br />June 13, 2008 <br />505 <br />June 11, 2008 <br />517 <br />September 16, 2010 <br />499 <br />June 7, 2012 <br />518 <br />September 9, 2012 <br />506 <br />November 18, 2012 <br />529 <br />March 11, 2013 <br />524 <br />June 3, 2013 <br />503 <br />The seasonal water level variation does not appear to correlate closely with <br />fluctuations in the concentration of dissolved sodium. The historical record of <br />