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<br /> <br /> <br /> <br /> <br /> <br /> <br />L1 <br /> <br />!J <br /> <br /> <br /> <br />t <br /> <br /> <br />f <br /> <br />is probably caused by early runoff at the mine site leaching pyritic and <br />organic sulfur as flow passes over and through the spoils. Since the flow of <br />Trout Creek is low at that time, the amount of sulfur is sufficient to cause <br />an ionic shift from a bicarbonate type water to a sulfate type. An <br />equalization in the sulfate-bicarbonate balance occurs downstream as the <br />source of the sulfate (mined areas) is unavailable and dilution by runoff from <br />undisturbed areas is introduced. During periods of higher flow the input of <br />sulfate is insufficient to shift the anion component to a sulfate type with <br />concentrations of bicarbonate and sulfate being approximately equal at TR-D. <br />Manganese (Figure 6) shows fairly consistent values since the fall of 1981, <br />except during 1984. At that time, a dramatic increase occurred upstream of <br />TR-A with significant dilution being observed at each successive monitoring <br />point along the mine area. The dilution was caused by the low concentrations <br />present in water exiting from the mine vicinity. All the manganese values <br />observed, except May, 1984, are consistent with the baseline values. The <br />relatively high values of manganese observed at TR-C (0.13 mg/1) and TR-D <br />(0.16 mg/1) during May of 1988 did not appear to be related to mining activity <br />as an elevated concentration was not observed at TR-B (0.04 mg/1) which is <br />immediately downstream of the active mine. <br />Orthophosphate (Figure 7), nitrite (Figure 7), unionized ammonia (Figure <br />8), and dissolved aluminum (Figure 8) were added to the monitoring program in <br />1988. All values obtained during 1988 and 1989 for these parameters were low <br />with most being below detection limits (see appendix). <br />IV. Ground Water <br />Ground Water Elevations <br />Water levels in the alluvial wells at the Edna Mine have remained constant <br />over the previous years with minor fluctuations occurring seasonally. <br />Elevations of the water in the alluvial wells and the spoils well are shown in <br />Figure 9. As suggested in the baseline studies, the occurrence of a drawdown <br />in any of the wells is anticipated only during mining at the base of the slope <br />near Trout Creek. <br />in reviewing the data, it is interesting to note that the spoils well has <br />II <br />J <br />