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• SURFACE WATER MONITORING <br />There are two rivers in the vicinity of the mine site. The Yampa River flows in a <br />southeasterly direction across the mine site. The Yampa River drains most of the <br />northwest corner of Colorado and part of south-central Wyoming. The second river is the <br />Williams Fork, which is a major tributary of the Yampa River. The Williams Fork River joins <br />the Yampa River on the mine property. Monitoring data is collected for the Williams Fork <br />River. Monitoring data is also collected from one spring, the #1 Strip Pit (NPDES site 022). <br />In 1994 there was no discharge from the sediment ponds. <br />RIVER FLOWS <br />The Williams Fork River flow data is collected by the US Geologic Survey at one <br />continuous gaging station and one staff gage. The Williams Fork River continuous gaging <br />station (WF-2) is near the confluence with the Yampa River, downstream of the #5 Mine <br />• discharge. The staff gage (WF-1) is located upstream of the mine discharge points. The <br />flow data for Station WF-2 for 1994 was provided by the USGS. A plot of daily mean flow <br />versus time for the Williams Fork River for 1994 is presented in Figure 25. For the <br />Williams Fork River at Cyprus Empire Corporation, flows measured by the USGS during <br />calendar year 1994 showed a maximum daily flow of 803 cfs and a minimum daily flow of <br />13 cfs. Monthly minimum, maximum and mean flows are plotted for each month of record <br />in Figure 26. The flows in the Williams Fork River during 1994 appear normal to slightly <br />below average for the period of record. These flows including comparison between <br />upgradient, WF-1, and downgradient, WF-2, measured to date, do not show any stream <br />depletion impacts from mine dewatering. <br /> <br />2 <br />