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<br />provided in Figure 21.2006 data indicates no significant impact on alluvial water quality or levels. <br />Historically, groundwater levels in the alluvium have remained fairly regular, with normal seasonal <br />fluctuations, apparently related to changes in river levels. Ground water levels for these wells is plotted in <br />Figure 19. The data indicates no impact on alluvial water levels related to mining. <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 River, flows in a southeasterly direction <br />across the mine site. The Yampa River drains most of the northeast corner of Colorado and part of south- <br />central Wyoming. The second river is [he Williams Fork, which is a major tributary of the Yampa River. The <br />Williams Fork River joins the Yampa River on the mine property. Monitoring data is collected for the <br />Williams Fork River. <br />The United States Geologic Survey (USGS) had one gaging station and one staff gage for collection of <br />Williams Fork River flow data (former site 09249750). The Williams Fork River gaging station (WF-2) is <br />near the confluence with the Yampa River, downstream of the Eagle No. 5 Mine discharge. The staff gage <br />(WF-1) is located upstream of the mine discharge points. WF-2 is also monitored concurrent with WF-1. <br />The flow data for WF-2 was historically provided by [he USGS, however, monitoring of the Williams Fork <br />stations was discontinued in 2001. Historically, comparisons between up gradient site WF-1, and down <br />gradient site WF-2, have not show any stream depletion impacts from mine dewatering. In 2006 the State <br />Division of Water Resources (Office of State Engineer) reactivated the site. Data for the former USGS site <br />can be found on their website under station No. WMFKMHCO. A preliminary copy of their data is provided <br />at the back of this AHR under Support Data. <br />Summaries of WF-1 and WF-2 water quality data are presented in Tables 27 through 30. A plot of upstream <br />and downstream dissolved solids measurements for the river is presented in Figure 22. Water quality data <br />does not show any significant variation from expected values. The comparisons of data from the upstream <br />and downstream station on the Williams Fork River indicate that there is no detectable effect of mining on <br />river water quality. As expected, dissolved solids decrease with increasing flow rate in the rivers, due to <br />dilution from runoff. <br />Page 6 <br />• 1:\8uv\8mpire\AHR\2006\Test\Empire2006AHR.doc <br />