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~ Water levels <br />• The plots of the historic water levels in four Foidel Creek alluvial wells are presented on <br />Figures 16 to 18. A plot of the historic water levels in some of the Fish Creek Wells in <br />the middle of Twentymile Pazk aze presented on Figures 19, 52, and 53. Plots of the <br />water levels in the alluvial wells in the vicinity of the Fish Creek Tipple are presented <br />on Figures 20 and 21. The water levels in the wells show the typical seasonal pattern <br />of relatively rapid increase and decline due to spring runoff. In addition they show the <br />general decline in water levels due to the relatively low runoff since 1987. <br />While the seasonal variation in water levels in the Foidel Creek alluvium is readily <br />appazent, no significant impact from underground mining is evident. The average water <br />levels in the three wells downgradient from the mine dischazge point at Pond D (001-S-5, <br />008-AV-1, and 008-AV-2) adjusted for differences in spring runoff, has not changed <br />since monitoring began in 1979. The Foidel Creek alluvial well upgradient from the <br />mine portal (009-S-10) shows a slight water level decline compazed with previous years. <br />The Fish Creek alluvium water level data for the wells upstream of the tipple is presented <br />for baseline purposes only. The water level data for the Fish Creek 'alluvial wells do not <br />show any impact from the activities at the tipple or the Fish Creek Borehole. <br />Water Ouality <br />The water quality data aze summarized in Tables 14 to 19 for the Foidel Creek alluvial <br />wells and Tables 20 to 29 for the Fish Creek alluvial wells. The historic electrical <br />conductivity concentrations for the Foidel Creek wells aze plotted on Figure 22. Seasonal <br />variation occurs in the wells due to the flushing effect of relatively low dissolved solids <br />surface water which rechazges the alluvial aquifers during spring runoff. There was a <br />small increase in the average salt content of the water starting in the 1987 water year <br />and continuing through the 1992 water year. This is probably due in part to the <br />relatively low runoff which has persisted since 1987. <br />The water quality in the Foidel Creek alluvial wells upstream and downstream of the <br />underground mine discharge show an increase in total dissolved solids and conductivity, <br />and change from asodium-bicarbonate type to a mixed calcium-sodium-bicarbonate- <br />sulfate type. This is primarily attributable to rechazge of alluvium by Foidel Creek water <br />which receives sediment pond discharges (containing elevated concentrations of dissolved <br />solids, calcium and sulfate) in the reach between the upstream and downstream wells. <br />The sediment pond water is largely derived from spoil runoff and spoil springs and, in <br />the case of Sediment Pond D, from underground mine discharge. The spoil springs, in <br />particulaz, have elevated sulfate, calcium, and dissolved solids concentrations. <br />(~ -5- 6/10/94 1:23 pm <br />