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<br /> <br /> the mine. This is not unexpected. As mentioned in the baseline study, the cause <br /> for the higher TDS levels occurring at TR-C is related to the relative positions <br /> of TR-C and TR-D to the active mining area. The dilution of TDS concentrations <br /> in the stream flow since 1988 has not been as pronounced as in previous years. <br /> The reason for this is not clearly understood since active mining directly above <br /> TR-C did not begin until 1990. It is possible that the trend prior to 1990 was <br /> reflecting an increase in disturbance activities such as farming along the <br /> western side of Trout Creek in the vicinity of the Edna Mine. All values for <br /> TDS, except one are consistent with the baseline samples. The sample taken at <br /> TR-C (TDS = 1658 mg/1) in December of 1985 appears to be an anomaly, perhaps the <br /> result of a laboratory analytical error as TR-D does not reflect an influx of <br /> TDS. <br /> nesium/Sodium <br />Cal <br />ium/Ma <br /> g <br />c <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 the <br /> relative proportions of these parameters change slightly between the sampling <br />' points, all show peak concentrations coinciding with spring runoff, as would be <br /> expected. As with TDS, all three cations show general increases in concentration <br /> as the water passes active mining areas. Additionally, the relative proportion <br /> of each constituent remains constant to the other constituents. While trends in <br />their subsequent dilution downstream have yet to form a consistent pattern, <br />little or no dilution in any of the concentrations have occurred between sampling <br />points TR-C and TR-D since 1985. For 1990-1994, it is believed that this was due <br />in part to the Moffat area mining activities and, as such, the pattern is <br />anticipated to continue. However, since this occurrence existed prior to the <br />initiation of Moffat mining activity, the trend may also suggest that inflow from <br />undisturbed areas upstream and downstream of TR-C contains approximately the same <br />concentrations of these parameters as runoff from the mine. <br /> <br /> <br /> <br /> 12 <br />