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Bicarbonate/Sulfate <br />As noted in previous annual hydrology reports, upstream of the mine on Trout Creek, bicarbonate (Figure 10) is the <br />major anion with sulfate (Figure I1) concentrations increasing rapidly along the mine area to become predominating <br />downstream (Figure 12). The sulfate levels increase is most markedly noticed prior to the peak flow period of Trout Creek <br />and adjacent fo where mining activity took place, as are TDS levels in general. This increase is probably caused by early <br />runoff at the mine site leaching pyritic and organic sulfur as flow passes over and through the spoils. Since the flow of Trout <br />' Creek is low at [hat time, the amount of sulfur is sufficient to cause an ionic shift from a bicarbonate type water [o a sulfate <br />type. During periods of higher flow and late in the season when runoff from the mine is small relative to total Trout Creek <br />' flow, the sulfate component is less able to shift the anion balance to a sulfate type with concentrations of bicarbonate and <br />sulfate being approximately equal downstream. <br />The 2003-2005 trend shows that the topological change generally still occurs at TR-B. This is believed to be the <br />' result of the spoil spring, which has developed a[ [he base of the West Ridge mining area. As reclamation of West Ridge <br />matures, the high levels of sulfur exhibited in the spring are anticipated to decrease. The 2003-2005 trend showing peak <br />' sulfate levels at TR-C and TR-D are expected to continue for some time as spoil springs in the Moffat area have developed <br />after the completion of mining in that area, Like the West Ridge area the sulfate sources within the Moffat azea are <br />' anticipated to diminish as vegetation establishes and matures. <br />While peak levels of individual constituents may be shifting as flow proceeds past the mine, they do not seem to be <br />increasing overall I[ is believed that an equalization in the sulfate-bicarbonate balance or a reversal (similar to the balance at <br />' TR-A) occurs downstream as the source of available sulfate (mining areas) is unavailable and dilution by runoff from <br />undisturbed areas is introduced. <br />Manganese <br />Manganese (Figure 13) shows fairly consistent values since 1989. Most of the manganese values observed are <br />consistent with baseline values. Manganese values appear to be developing a trend, which may be directly related to flow in <br />Trout Creek as are the TDS concentrations. Sampling in October of 2005, at site TR-D, produced an inconsistent spike of <br />manganese up to 0.248 mg/L. Manganese remained within historical levels at all other sites along Trout Creek in October <br />2005. The October water quality data was re-analyzed and the original values were confirmed. There is no apparent reason <br />for this sudden rise in value. Manganese will be closely monitored in 2006. <br />14 <br />