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Total Dissolved Solids <br />Total Dissolved Solids (TDS) concentrations (Figure 6) in Trout Creek exhibit an expected pattern. As stream flow <br />passes [he mine, TDS levels increase while adjacent ro the mined areas and then begin to decline downstream due to inflow <br />from undisturbed lands below the active mine. Peak TDS levels in Trout Creek adjacent to the mine occur in early spring <br />prior to [he period of peak flow. This is caused by the spring runoff from the portion of the watershed in which the Edna <br />Mine is located. Although TDS concentrations in the mine runoff may be quite high when compared to concentrations <br />occurring above the mine, generally the mine runoff is small relative to Trout Creek's total flow. Therefore, a significant <br />increase in Trout Creek TDS levels is observed only during the initial stages of spring mnoff. A comparison of [he TDS and <br />Flow indicates that TDS concentrations appear to be directl y related to flow volume. <br />The dilution of TDS concentrations in downstream flow for the past decade has not been as pronounced as in <br />previous decade. Beginning in 1990, mining and reclamation occurred in close proximity to TR-C. As such, dilution of TDS <br />concentrations probably occurs farther downstream of TR-D as runoff from undisturbed areas enters into Trout Creek. <br />Although elevated TDS concentrations have moved downstream in conjunction with mining and reclamation activities, all <br />values for TDS are consistent with the probable hydrologic consequences projections. <br />Calc ium/M agnesium/Sodi um <br />Calcium (Figure 7) is the dominant cation in Trout Creek with magnesium (Figure 8) and sodium (Figure 9) <br />occurring in lesser concentrations. While the relative proportions of these parameters change slightly between the sampling <br />points, all show peak concentrations coinciding with spring runoff, as would be expected. As with TDS, all three cations <br />show general increases in concentration as [he water passes the mine area. Additionally, the relative proportion of each <br />constituent remains constant to [he other constituents. While [rends in their subsequent dilution downstream have ye[ [o form <br />a consistent pattern, little or no dilution in any of the concentrations have occurred between sampling points TR-C and TR-D <br />since 1989. For 1992-2002, it is believed that this was due in part to the Moffat area mining and reclamation activities and, as <br />such, the pattern is anticipated to continue. However, since this occurrence existed prior to the initiation of Moffat mining <br />activity, the trend may also suggest [hat inflow from undisturbed areas upstream and downstream of TR-C contains <br />approximately the same concentrations of these parameters as runoff from the mine. <br />9 <br />