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higher then the standards include sulfates, sulfides (un-ionited ), iron, manganese, cadmium, copper, chromium, and nickel. !t is noteworthy of mentioning that even Site 11, • which is upstream of Seneca II Mine discharges, exceeds the iron standard. The high cadmium value (2.9 mg/I) mentioned in the previous paragraph (at NPDES 008) is most likely incorrect. The highest concentration noted since the detection limit was changed from 5 ug/l to 0.1 ug/l, was 0.6 ug/l, with 11 of the 14 analyses reporting Less then 0.1 ug/l. Likewise, the high copper (290 ug/l), chromium (300 ug/l), and nickel (290 ug/I) values for Site b on March 8, 1994 ere also likely to be incorrect. The highest previous copper concentration was 10 ug/l, with 21 of the 23 analyses being less then the detection Limit of 10 ug/l. The highest previous chromium concentration was 40 ug/l, with 19 of the 23 analyses being less then the detection limit of 10 ug/l. The highest previous nickel concentration was 20 ug/l, with 20 of the 23 analyses being less than the detection limit of 20 ug/l. it should be noted that a sample from NPDES 004, immediately above Site 6 and collected on the same day, had Concentrations of these three trace metals below [heir detection limits. 4ater discharged from the Seneca II Mine is not used directly for irrigation. Indirectly, although, water discharged from the mine is significantly diluted by water from either • Fish Creek ar the Yampa River before is is diverted and used for irrigation. Due to the relative amount of dilution by additional water from both sources, the ambient water qualities of Fish Creek and the Yampa River are the dominant factors in determining their suitability for irrigation. Hater discharged from the Seneca II Mine is used for livestock watering. Table 21 presents the most stringent livestock standards as compiled from various organizations by the OSMRE (OSMRE, 1989). Surface water quality measured at stream and NPDES sites during 7994 were compared with the livestock standards, and the comparison results are presented in Table 22. pH was measured at higher levels than the livestock standard at four sites. High sulfate and chromium values at Site 6 were observed, although the chromium values are suspect (see the second paragraph above). NPDES 002 had one high fluoride value (2.0 mg/l); however, this value is also suspect since the highest previous concentration was 0.62 mg/l with an average for 39 samples of 0.45 mg/l. As a final note, no eaceedences of NPDES effluent criteria (Permit No. CO-000022)) were observed at the outfalls associated with the Seneca II Mine during 1994. • 18