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. Similarly, the COON has established a standard of .002 mg/L for unionized sulfide as <br />hydrogen sulfide (R2S). it should be noted that the water quality analyses in the <br />appendices of this AHR report the sum of ionized and un-ionized sulfide as sulfide. To <br />compare Peabody's reported sulfide concentrations against the stream standard, it is <br />necessary to convert the reported concentration to un-ionized sulfide as hydrogen sulfide. <br />This is accomplished in two steps. Sulfide values are converted to sulfide as hydrogen <br />sulfide by multiplying by 1.Ob. To express the sulfide as hydrogen sulfide values in <br />terms of un-ionized sulfide, the procedure on Page 477 of "Standard Methods for the <br />Evaluation of water and wastewater" (AP HA, 1985) was used. The procedure consists of <br />multiplying the sulfide as hydrogen sulfide values by a percentage of un-ionized sulfide <br />correction factor. Since any sulfides in surface water should be rapidly oxidized to <br />sulfates, it is likely that any sulfides detected in surface eater are the result of <br />suit ides existing in the suspended solids, or are the result of interferences with the <br />sulfide analyses. <br />Table 23 (Appendix A) presents the results of comparing surface water quality data <br />(stream sites, NPDES sites) collected during the 1990 water year against stream standards <br />established for Segment 13 of the Yampa River. Table 23 shows that all surface water <br />sites, 1nClUding NPDES sites, exhibited higher levels of select parameters than the <br />standards established for Segment 13. Sulfate was commonly higher than the stream <br />standard at all sites in 1990. Other parameters that were analyzed at higher <br />concentrations than the standards at most sites include manganese, iron, ammonia <br />(un-ionized) and nitrite. <br />Interestingly, Site 11 (sw-52-11) on Fish Creek, which is located above the confluence <br />with Cow Camp Creek and is also unaffected by discharges from active mining areas at <br />Seneca lI, exhibited the most parameters that were analyzed at higher concentrations than <br />the stream standards (sulfate, total iron, un-ionized ammonia, un-ionized sulfide, end <br />lead). The higher-then-standard levels of sulfate and total iron measured et Site 10 (Cow <br />Camp Creek), and the higher-than-standard level of sulfate measured at Site 12 (Bond <br />Creek) on May 3, 1990, had only a minor effect on these same parameter levels measured <br />downstream along Fish Creek at Site 13 on the same day (sulfate - 115 mgl l; total iron = <br />2.40 mgJl, see Appendix E>. <br />The comparison between surface water quality data collected in 1990 at Seneca tI surface <br />water sites and Segment 13 stream standards show that at least two parameters analyzed for <br />at each site have been at higher concentrations that the standards, with sulfate being <br />21 <br />