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83-01. The decline during the first part of 1991 also pazallels the trend in these two wells. However, the rapid • decline during the last part of 1989 and the first part of 1990 appears to follow the trend observed in Well 83- 02 although the magnitude of decline is considerably less. As indicated above, TR-4 recovered to more historical levels in 2001. Well 83-03 (Figure 9) is the Middle Sandstone monitoring well located furthest (more than 1.5 miles) from active underground operations for Mines 5 and 6. Historically, the overall trend from 1984 through 2001 suggests a similaz trend to the other Middle Sandstone wells. The long tetra decline could be a pressure response due to the overall drop in potentiometric levels in the Middle Sandstone in the vicinity of Mines 5 and 6. Except for Well 83-03, the water levels in the Middle Sandstone wells had either recovered or stabilized in 1995. The water level data collected for the other Middle Sandstone wells continue to display increased stability and a slow recovery. The groundwater gradient in the Middle Sandstone in the vicitilty of the mining operation generally decreases from the southeast to the northwest as reflected on Figure 11. The field parameter data for the three Middle Sandstone wells (TR-4, TR-7A, 81-O1), again, suggest no adverse impact or trend. Water quality data are summarized in Tables 7 through 12. Plots of field conductivity for these Middle Sandstone Wells are presented in Figure 14. The conductivity measurements recorded at well 81-O1 continue to stabilize at values neaz those typically observed for the other Middle Sandstone wells (TR-4 AND TR-7A). Wells TR-7A and TR-4 indicate slight reduction hi concentrations of major ions over time. Historically, all three wells show reduction in concentrations of iron, and indicate • considerable variation in concentrations. The general reduction in iron concentrations may have been the result of better purging of well bore volumes prior to sampling plus a switch to dissolved concentration analysis. Twentymile Sandstone: Monitoring results through yeaz 1995 (Fig. 10) showed no appazent change in the water levels that could be attributable to mining activities. During 2000, 9 Mine well displayed some unusual fluctuations, while wells 259 and 84-01 remained stable. Those responses aze not believed to be mine-related, as no unusual activities or additional mining occurred in the vicinity of these wells during 2000. 9 Mine well returned to historical levels in 2001. The piezometric contour map of the Twentymile Sandstone is presented as Figure 12. This gradient remains generally consistent with previous years, according to 2001 measurements. The 2001 field parameter data for the two Twentymile Sandstone wells (No. 9 Mine Well and We11259), do not suggest significant impacts or trends. Water quality data for these Twentymile Sandstone wells aze summarized in Tables 13 through 16. Plots of field conductivity over time are presented in Figure 15. Measurements during 2001 appeared normal. 3.1.2 Mine Water Discharge • Plots of [he measured dischazges for the two Eagle No. 5 Mine dischazge points aze presented in Figure 16. 4 I:\Env\Empire\AHR\2001 \Text\Empire2001 AHR.doc