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Parameter # of Sites / # of Excursions <br />Manganese (CDPHE irrigation) 1/2 <br />This summary indicates that only one CDPHE surface water agricultural <br />use standards were exceeded. The manganese standard was exceeded twice <br />at NPDES8. However, as indicated in the recently revised CDPHE <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 II <br />region, a more appropriate (EPA) standard would be 10 mg/l. The maximum <br />manganese value observed this year at any surface water site was 1.61 <br />mg/l. <br />Table 12 shows the CDPHE receiving stream standards for Fish Creek <br />(Yampa Segment 13b). Table 13 provides a comparison of those standards <br />to water quality data collected this year from NPDES and stream sites in <br />the Fish Creek basin. The stream standards for Fish Creek are based on <br />aquatic life standards, even though there are no fish present in the <br />tributary that NPDES8 discharge into. Standards that were exceeded are: 10 <br />Parameter # of Sites / # of Excursions <br />Iron, Total Rec. 3/5 <br />Selenium 1/1 <br />All iron excursions (standard 1.0 mg/1) were the result of high <br />suspended solids. Only one of the iron excursions was at NPDES8, with a <br />value of 1.01 mg/1 in February. This is the first time, since monitoring <br />for total recoverable iron began (1990), that an iron exceedance <br />occurred. By March, the iron value decreased to 0.38 mg/1. <br />One sample from NPDES8 exceeded the chronic selenium standard, 4.6 ug/1, <br />with a value of 7.2 ug/l, but not the acute standard,. 18.4 ug/1. <br />SCC runs two different mercury tests, a high level test with a MDL of <br />0.2 (or sometimes 0.4) ug/l (for streams and NPDES sites), and a low <br />level test with a MDL of 0.0002 ug/l (for NPDES sites only). All high • <br />11