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exceedence out of two samples). Below is a summary of standards that • were exceeded. Given in parenthesis is the source and use of each standard. Although the CDOH does not indicate between livestock and irrigation uses in their surface water agricultural standards, they have done so in their similar ground water agricultural standards (see Table 5). For the sake of discussion, SCC chooses to use those ground water use standards classifications (livestock or irrigation) for surface water use evaluation. Following is a list of standards exceeded this year. # of Sites / # of Excursions Manganese (CDOH irrigation) Potentially Dissolved 3/3 Manganese (CDOH irrigation) Total 4/4 This summary indicates that only one CDOH surface water agricultural use standard was exceeded. The manganese standard was exceeded at four • sites (total) or three sites (potentially dissolved). SCC changed the analytical type from total to potentially dissolved in the middle of 2006 (per TR-28). However, as indicated in the recently revised CDOH Regulation 31, the standard of 0.2 mg/1, applies to plants grown in acidic (<6.0 pH) soils. In alkaline soils, as are found in the Seneca II region, a more appropriate (EPA) standard would be 10 mg/1. The maximum manganese value for any surface water site observed this year was 1.06 mg/1. Premining manganese values often exceeded the 0.2 mg/1 standard. Table 11 shows the CDOH receiving stream standards for Sage and Grassy Creeks (Yampa Segment 13e, Reg. 33, December 2005). These standards were based on the presence of fish in the lower portions of the creeks. However, the upper portions that the Yoast Mine discharges into have no fish present. Table 12 provides a comparison of those standards to water quality data collected this year from NPDES and stream sites in the Sage and Grassy Creek basins. Standards that were exceeded are: 13