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• Iron Iron concentrations were elevated during the fourth calendar quarter of 2000, significantly so for well 95-1. During the second sampling this year, all wells revealed reduced iron concentrations, leading to the conclusion that the fourth quarter 2000 value for well 95-1 was an aberrant concentration. This water year, iron concentrations in well 17-B showed a spike similar to that of well 95-1 two years prior. As before, the level attenuated the following quarter. Magnesium Magnesium concentration levels in all groundwater monitoring wells remained within historic values during this water year. Well 17-B shows the least overall variability for magnesium values of the three wells, ranging from 5.7 to 19.0 mg/L over the past eight years. Well 94-1 showed the widest range in values, ranging from 22.4 mg/L (W.Y. 1997) to 128.0 mg/L (W.Y. 1995). Magnesium values for we1195-1 were intermediate between wells 17-B and 94-1. Wells 94-1 and 95-1 show a slight overall decrease in concentrations over the past eight water years. Sodium Sodium concentrations within all wells remained within historic ranges this water year. • Wells 17-B and 94-1 show significant variability in the range of sodium values, while well 95-1 shows minimal concentration variability over the past eight water years. Sulfate Sulfate concentrations vary widely within and between the wells. Well 17-B has had consistently low sulfate levels throughout the past eight water years. Well 94-1 reveals a wide range of sulfate concentrations ranging from 42 mg/L (W.Y 1999) to 680 mg/L (W.Y. 1995). Concentration fluctuations have attenuated over the past three water years, remaining in the 205-360 mglL range. Weil 95-1 illustrated wide initial fluctuations in sulfate concentrations (W.Y. 1997-1998) with subsequent water years revealing no detectable sulfate concentrations. Trace Elements Many of the trace elements found to be below the detection limits for the springs sampled were also found to be below detection limits for the wells sampled. These trace elements are arsenic, cadmium, carbonate, mercury, nitrite, nitrate, nitrate/nitrite, total phosphate, selenium, and zinc. Other trace elements found at detectable limits are consistent within each well at levels that do not indicate high or low fluctuations of these elements. Overall, elements that are detectable and those that are not have been consistent throughout the groundwater well monitoring program at the Carbon Junction Mine. Larbon Junction Mine Page 10 Annual F~drologb Reportfor Water Year?A02