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established for Segment 13 (see Table 19, Appendix A) have been used to compare against surface eater qualify measured at the Seneca II Mine (Grassy Creek, Fish Creek ~ LO V, tributaries, and Fish Creek). ,. a 9 ;.~ For Segment 13 of the Yampa River, the CD OH has established a standard of 0.02 mg/t for ~a un-ionized ammonia. Analyses performed by Peabody's contract laboratory for ammonia as nitrogen resulted in reported values consisting of the sum of both the ammonium ion (.ionized) and ammonia (un-ionized). Because of this, it was necessary to convert Peabody's reported ammonia concentrations to un-ionized ammonia concentrations in order to compare them against the stream standard. The table presented on Page 713 of "Standard Methods for the Examination of Water and Wastewater" (APHA, 1985) presents percent correction factors used to calculate un-ionized portions of ammonia in distilled water. Since percent correction factors for solutions with higher TDS are unavailable in the literature, percent correction factors for distilled water were applied to the ammonia values for comparison purposes. It should be noted that the percent un-ionized ammonia decreases with increasing TDS, and resultant values calculated for un-ionized ammonia are probably higher than the true value. ~~ S~ g • Similarly, the CDOH has established a standard of .002 mg/l for un-ionized sulfide as ?R' hydrogen sulfide (H S). It should be noted that the water quality analyses in the \\V ~t- 2 appendices of this AHR report the sum of ionized and un-ionized sulfide as sulfide. 70 compare Peabody's reported sulfide concenfrations against the stream standard, it Is necessary to convert the reported concentration to un-ionized sulfide as hydrogen sulfide. This is accomplished in tuo steps. Sulfide values-are-conver[ed_to sulfide as hydrogen /-' sulfide by multiplying by 1.06. To express the sulfide as hydrogen sulfide values in terms of unionized sulfide, the procedure on Page 477 of "Standard Methods for the Evaluation of Water and Nastewater" (APHA, 1985) Mas used. The procedure consists of multiplying the sulfide as hydrogen sulfide values by an un-ionized sulfide correction factor. Since any sulfides in surface water should be rapidly oxidized to sulfates, it is likely that any sulfides der eared in surface water are the result of sulfides existing in the suspended solids, or are the result of interferences with the sulfide analyses. Table 20 (Appendix A) presents the results of comparing surface water quality data from all NPDES sites and selected upstream and downstream surface water sites collected during 1991 against ODOR stream standards established for Segment 13 of the Yampa River. Table 21