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Permit C-81-071 1994 Annual Hydrology Report <br />Water Levels <br />The plots of the historic water levels in the spoil wells are presented on Figures 16 through 19. <br />The water levels normally have a similar pattern to the alluvial wells: they respond rapidly to the <br />spring runoff and then decline rapidly in the summer. Wells 026-SP-1 and 026-SP-3 are <br />sometimes dry by the fall, although this has not happened since 1988. These water levels <br />closely mirror the pattern of the spoil spring discharges discussed later in the report. Wells 001- <br />SP-6 and 001-SP-7 reflect fluctuation of the spoil aquifer due to pumping activities associated <br />with the adjacent Foidel Creek Mine. <br />Water Quality <br />The water quality data area summarized in Tables 24 through 29 for the spoil wells. The <br />historic dissolved solids concentrations for the wells are plotted on Figure 20. The dissolved <br />solids concentrations in all wells show temporal fluctuations that most likely reflect recharge <br />events of low TDS snowmelt. The lowest TDS concentrations in the spoil groundwater typically <br />occur during the Spring snowmelt period. Dissolved solids have not shown any significant <br />increase since 1989. The spoil groundwater has comparable dissolved solids concentrations to <br />most of the spoil spring discharge, but much higher values than in the background bedrock <br />ground water. The spoil ground water is a calcium-sulfate type with relatively high <br />bicarbonate and low SAR. Spring 114 has higher sodium and sulfate than other spoil springs. <br />The data does not indicate any significant changes in the trace metals concentrations. <br />SURFACE WATER MONITORING <br />Four primary locations and one water level only location on Foidel creek in the vicinity of Mine 1 <br />are monitored. Station 14 is upstream of the effects of all mining activities in the area. USGS <br />Station 09243800 (Station 800) is a short distance downstream of Station 14 and is <br />downstream of the discharge point for Pond A, which captures the drainage from a large area <br />of spoil springs. Station 8 is a short distance downstream of Mine No. 1 and the Foidel creek <br />underground mine portal. l1SGS Station 09243900 {Station 900) is located upstream of the <br />confluence of Foidel and Middle Creeks. A water level only station (304) is located near well <br />008-AV-2 near the confluence of Foidel and Middle Creeks. <br />Two primary locations on Fish Creek are monitored. Station 16 is located immediately <br />downstream of where Fish Creek enters the south end of Twentymile Park. This station has <br />replaced Station 1001 that was Iccated upstream of where Fish Creek enters Twentymile Park. <br />Station 1002 is located on Fish Creek about one-half way through its reach in Twentymile park <br />and downstream of Mine No. 2. One water level only station (307) is {ocated near Well 006-AZ- <br />3. <br />One station on Middle Creek, USGS Station 09423700 (Station 700) located upstream of Mine <br />No. 3, is monitored for flow and water quality. Two locations on Trout Creek are monitored. <br />Station 69 is located below the confluence with Middle Creek to which Foidel Creek is tributary. <br />Station 301 is located upstream of the confluence of Middle and Trout Creeks. <br />• <br />EP4TE%T DOC 07/17/97 Page 4 <br />