Laserfiche WebLink
i and AVF-6. Water quality data for these three wells is provided in Tables 21 through 26. Conductivity data is <br />provided in Figure 21. 2009 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 the 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 />(WT-1) is located upstream of the mine discharge points. WT-2 is also monitored concurrent with WT-1. <br />The flow data for WT-2 was historically provided by the 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 October 2006 the <br />State Division of Water Resources (Office of State Engineer) reactivated the site. Data for the former USGS <br />site can be found on their website under station No. WNVI KMHCO. A copy of the daily average flow data at <br />this site for 2009 is provided 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. Dissolved solids decrease with increasing flow rate in the rivers, due to runoff dilution. <br />3.2.2 Springs <br />There is one active spring on the mine site area, known as the No. 1 Strip Pit Discharge, or 1SP. There are a <br />Page 6 <br />G:\Environmental\EM P[RE\AHR\2009\Empire2008AH R.doc