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This summary indicates that only one CDOH surface water agricultural use <br />standard was exceeded. The manganese standard was exceeded at eight <br />sites (total) or five sites (potentially dissolved). SCC changed the <br />analytical type from total to potentially dissolved in the middle of <br />2006 (per TR-52). However, as indicated in the recently revised CDOH <br />Regulation 31, the standard of 0.2 mg/1, applies to plants grown in <br />acidic (<6.0 pH) soils. In alkaline soils, as are found in the Seneca <br />II-W region, a more appropriate (EPA) standard would be 10 mg/1. The <br />maximum manganese value for any surface water site observed this year <br />was 1.35 mgll at Spoil Spring 3. Premining manganese values often <br />exceeded the 0.2 mg/1 standard. <br />Table 11 shows the CDOH receiving stream standards for Dry Creek (Yampa <br />Segment 13d) and Sage Creek (Yampa Segment 13e). Sage Creek was <br />resegmented by the CDOH in 2003. Regulation 33 was further revised in <br />December 2005. These standards were based on the presence of fish in <br />the lower portions of the creeks. However, the upper portions that <br />Seneca II-W discharges into have no fish present. All standards for 13d <br />and 13e are the same except £or selenium (see Table 11). Table 12 <br />provides a comparison of those .standards to water quality data collected <br />this year from NPDES and stream sites in those basins. Standards that <br />were exceeded are: <br />Parameter # of Sites / # of Excursions <br />Iron 3/3 <br />Nitrite 2/3 <br />Sulfide 3/3 <br />Only one of the five iron exceedences was from a NPDES site. It was due <br />to suspended solids, 10 mg/1. This strict aquatic life standard (1.0 <br />mg/1) was exceeded in over half of the premining stream samples. Three <br />samples from NPDES sites exceeded the nitrite standard. Nitrites are <br />unstable in aerated water (Hem, 1989), and will oxidize to nitra tes. <br />Nitrite values in the streams below the NPDES discharges were below the <br />standard. <br />22 <br />