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Rivers. The Yampa River upstream site is labeled Y-1 and the downstream site is labeled Y-2. The Williams Fork <br />River upstream site is labeled WF-1 and the downstream site is labeled WF-2. The two (2) sampling sites on the <br />Yampa River are located upstream and downstream of its confluence with the Williams Fork River. The locations of <br />the four-(4) sampling sites are shown on the Hydrologic Monitoring Program Location Map {Map 1 I). The Yampa <br />River stations, Y-1 and Y-2, were monitored in conjunction with the No. 9 Mine and are no longer monitored. These <br />stations will be reestablished prior to the development of the North Mains. The monitoring plan has been modified to <br />include these new sites and a new site (Y-3). <br />Chemistry data for all four (4) sampling sites is presented in Table 25, Summary of Water Quality Data -Yampa <br />River (Y-1) Downstream, Table 24, Summary of Water Quality Data -Yampa River (Y-2) Upstream, Table 26, <br />Summary of Water Quality Data -Williams Fork River (WF-1) Upstream, and Table 27, Summary of Water Quality <br />Data -Williams Fork River (WF-2) Downstream. <br />Downstream Yampa River Sampling_Site (Y-1) <br />Surface water from the Yampa River sampling site (Y-1), downstream of the confluence with the Williams Fork <br />River, is of the calcium-sodium bicarbonate type. The percentage of calcium cations measured at the downstream site <br />is greater than that which is measured at the upstream site (Y-2). This probably reflects the effect of inflow from the <br />Williams Fork River. Dissolved Solids concentrations average 294 mg/L with amaximum-recorded concentration of <br />595 mg/L. The maximum recorded dissolved solids concentration is lower than the maximum dissolved solids <br />concentration recorded at the upstream Yampa River sampling site. This increase reflects the higher dissolved solids <br />concentrations of [he Williams Fork River. The pH values ranged from 7.60 to 8.79 and averaged 8.10. These values <br />resemble the values for pH recorded at the upstream site. Iron concentrations were greater than the upstream sampling <br />site. Iron concentrations ranged from 100 ug/L to 7,111 ug/L with an average of 1,554 ug/L. Manganese ranged from <br />less than 20 ug/L to 380 ug/L and averaged less than 76 ug/L. <br />Upstream Yampa River SamolinQ Site (Y-2) <br />Surface water from the upstream Yampa River sampling site (Y-2) is of the calcium-sodium bicarbonate type. <br />Calcium and sodium cations were recorded in nearly equal proportions. Dissolved solids concentrations are lower in <br />the Yampa River than in the Williams Fork River. Dissolved solids averaged 28l mg/L with amaximum-recorded <br />concentration of 640 mg/L. The pH values ranged from 7.30 to 8.81 and averaged 8.06. Average iron concentrations <br />were lower than the concentrations of iron recorded for the Williams Fork River and showed less variance. Iron <br />concentrations at the upstream Yampa sampling site ranged from 20 ug/L to 2,090 ug/L and averaged 785 ug/1. <br />Manganese concentrations ranged from less than 20 ug/L [0 470 ug/L and averaged less than 77 ug/L. <br />Upstream Williams Fork River Sampling Site (WF-1) <br />The upstream Williams Fork sampling site (WF-1) is located at the southern permit boundary. Examination of Table <br />26, Summary of Water Quality Data -Williams Fork River {WF-1) Upstream, indicates acalcium- bicarbonate type <br />of water. Calcium constitutes the major cation in solution, although magnesium and sodium are present in significant <br />proportions. Dissolved solids concentrations average 346 ug/L, with amaximum-recorded concentration of 588 ug/L. <br />Total iron and manganese concentrations varied considerably. Iron concentrations ranged from less than 80 ug/L to <br />11,800 ug/L. Average iron concentrations was 1,881 ug/L. Total maganese concentrations ranged from less than 20 <br />ug/L to 220 ug/1, with an average concentration of less than 106 ug/L. The pH values ranged from 7.40 to 8.79 and <br />averaged 8.14. <br />Downstream Williams Fork River Site (WF-2) <br />Surface water sampled from the downstream Williams Fork sampling site (WF-2) is of the calcium-bicarbonate type. <br />The water is similar to the upstream site; however, a higher proportion of sodium is evident. This may be a result of <br />discharges from the No. 5 and No. 6 Mines, previous discharges from the No. 9 Mine, and discharges from the <br />Permit Renewal No. 4 2.04-23 Revised 3/5/03 <br />