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• to Trout Creek's total flow. Therefore, a large increase in Trout Creek TDS <br />levels is not observed. A comparison of the TDS and Flow indicates that TDS <br />concentrations appear to be directly related to flow volume. <br />Prior to 1991, the TDS concentrations in Trout Creek reached the highest <br />levels at TR-C. This is not unexpected. As mentioned in the baseline study, <br />the cause for the highest TDS levels occurring at TR-C is related to the <br />relative positions of TR-C and TR-D to the active mining area. The dilution <br />of TDS concentrations in the stream flow since 1988 has not been as pronounced <br />as in previous years. The reason for this is not clearly understood since <br />active mining directly above TR-C did not begin until 1990. It is possible <br />that the trend exhibited from 1988 to 1990 was reflecting an increase in <br />disturbance activities such as farming along the western side of Trout Creek <br />in the vicinity of the Edna Mine. Since 1990, active mining has been in close <br />proximity to TR-C with dilution of TDS concentrations occurring downstream of <br />TR-D. Although elevated TDS concentrations have moved downstream in <br />conjunction with the active mining, all values for TDS are consistent with the <br />initial hydrology study projections. <br />• Calcium/Magnesium/Sodium <br />Calcium (Figure 7) is the dominant cation in Trout Creek with magnesium <br />(Figure 8) and sodium (Figure 9) occurring in lesser concentrations. While <br />the relative proportions of these parameters change slightly between the <br />sampling points, all show peak concentrations coinciding with spring runoff, <br />as would be expected. As with TDS, all three cations show general increases <br />in concentration as the water passes active mining areas. Additionally, the <br />relative proportion of each constituent remains constant to the other <br />constituents. While trends in their subsequent dilution downstream have yet <br />to form a consistent pattern, little or no dilution in any of the <br />concentrations have occurred between sampling points TR-C and TR-D since 1986. <br />For 1990-1995, it is believed that this was due in part to the Moffat area <br />mining activities and, as such, the pattern is anticipated to continue. <br />However, since this occurrence existed prior to the initiation of Moffat <br />mining activity, the trend may also suggest that inflow from undisturbed areas <br />upstream and downstream of TR-C contains approximately the same concentrations <br />of these parameters as runoff from the mine. <br />12 <br />