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' alluvium are plotted in Figure 21. ~ A piezometric map for. the <br />Williams Fork Alluvium (September 1988) is presented in Figure 22. <br />' Water Quality <br />Summaries of the water quality data for the alluvial wells are <br />presented in Tables 21 through 26. A plot of field electrical <br />conductivity versus time is presented in Figure 23. <br />The date flow data for Station WF-2 for January through September, <br />1988 were taken from published USGS reports. The data for October <br />through December was derived from unpublished, unchecked, gauge <br />height data supplied to Cyprus by the USGS. The actual flow rates <br />for this period will be slightly different than these used in this <br />report. <br />' There is no evidence of seasonal variation of water quality in the <br />~ alluvium. The field conductivity of Well AVF-5 was above normal <br />~~ in late 1983 and early 1984. The laboratory measurements did not <br />' ,~ show the same high levels during that period. The Williams Fork <br />_.,~. alluvial wells are showing a small upward trend in dissolved <br />solids. This is most evident in Wells AVF-3 and AVF-6.( There is <br />' ~ also a correlative increase in calcium, magnesium, sulphate and <br />~~ chlorides. The source of this change is unknown. Fi~ever, it is <br />probably not from the mine discharge because iit/~is~,~sodium <br />bicarbonate water. // <br />SURFACE WATER MONITORING <br />' -There are two rivers in the vicinity of the mine site. Th ~ajor <br />river, the Yampa, flows in a southeasterly direction across the <br />' mine site. The Yampa River drains most of the northeast corner of <br />Colorado and part of south-central Wyoming. The second river is <br />the Williams Fork, which is a major tributary of the Yampa River. <br />The Williams Fork River joins the Yampa River on the mine property. <br />' Data is collected for the Williams Fork River. In addition, data <br />is collected from one spring: the No. 1 Strip Pit (NPDES site). <br />' RIVERS <br />River Flow <br />1 The Williams Fork River flow data is collected by the U.S. Geologic <br />Survey at one continuous gauging station and one staff gauge. The <br />' Williams Fork River continuous gauging station is near the <br />confluence with the Yampa River downstream of the No. 5 Mine <br />discharge (WF-2). The staff gauge (WF-1) is located upstream of <br />' the discharge point. <br />4 <br />1 <br /> <br />