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Sandstone water (typically a strongly sodium-bicarbonate water). <br />• 3.2 Surface Water Monitoring <br />3.2.1 Rivers <br />There are two rivers in the vicinity of the mine site. The Yampa, flows in a southeasterly direction across the <br />mine site. The Yampa River drains most of the northeast comer of Colorado and part of south-central <br />Wyoming. The second river is the Williams Fork, which is a major tributary of the Yampa Rivet The <br />Williams Fork River joins the Yampa River on the mine property. Monitoring data is collected for the <br />Williams Fork Rivet Monitoring data is also collected from one spring, the No. 1 Strip Pit (CDPS Outfall <br />022). <br />The U.S. Geologic Survey at one continuous gaging station and one staff gage collects the Williams Fork <br />River flow data. The Williams Fork River continuous gaging station (WF-2) is near the confluence with the <br />Yampa River, downstream of the Eagle No. 5 Mine discharge. The staff gage (WF-1) is located upstream of <br />the mine discharge points. The flow data For Station WF-2 for 2001 was provided by the USGS. A plot of <br />daily mean flow versus time for the Williams Fork River for 2001 is presented in Figure 22. For the <br />Williams Fork River at RAGEC, flows measured by the USGS during calendar year 2001 showed a <br />maximum mean monthly flow of 1410 cfs and a minimum mean monthly flow of 25 cfs. Monthly minimum, <br />maximum and mean flows are plotted for each month of record in Figure 23. The flows in the Williams Fork <br />• River during 2001 appear to be about average for the period of record. These flows, including comparison <br />between up gradient site WF-1, and down gradient site WF-2, measured to date, do not show any stream <br />depletion impacts from mine dewatering. <br />Summaries of the water quality data are presented in Tables 27 through 30. A plot of upstream and <br />downstream dissolved solids measurements for the river is presented in Figure 24. The data indicates that the <br />surface water quality does not show any significant variation from expected values. The comparisons of data <br />from the upstream and downstream station on the Williams Fork River indicate that there is no detectable <br />effect of mining on river water quality. As expected, dissolved solids decrease with increasing flow rate in <br />the rivers, due to dilution from mnoff. <br />3,2.2 Springs <br />One spring on the mine site azea is being monitored. The spring is the #1 Strip Pit Discharge. The No. 1 Strip <br />Pit Discharge is a CDPS monitoring point (Outfal] 022). There are a few other springs and local permanent <br />"damp spots" in the area; however, their combined flow is normally less than 10 gpm and is therefore not <br />significant. The annual discharges for the No. 1 Strip Pit aze presented in Figure 25 and the 2001 discharge <br />measurements are presented on Figure 26. The discharge from the No. 1 Strip Pit increased significantly h1 <br />1989. This may have been due to seepage from the ditch that conveys the 7 North Angle discharge. The 7 <br />North Angle discharge began in January of 1989. However, discharge rates from 1990 through 2001 appear <br />• lower. Nevertheless, snowmelt and ditch seepage both appear to have some influence on the Strip Pit <br />6 <br />I:\Env\Empire\AHR\2001\Texl\Empire2001 AHR.doc <br />