2009-02-26_REPORT - C1980005 (7)

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Table 11 shows the CDPHE receiving stream standards for Fish Creek (Yampa Segment 13b). Table 12 provides a comparison of those standards to water quality data collected this year from NPDES and stream sites in the Fish Creek basin. The stream standards for Fish Creek are based on aquatic life standards, even though there are no fish present in the tiao tributaries that NPDES4 and NPDES8 discharge into. Standards that were exceeded are: Parameter # of Sites / # of Excursions Iron, Total Rec. 2/4 Manganese 1/1 Selenium 1/1 Sulfide 1/1 All iron excursions were the result of high suspended solids. None 'of the iron excursions were at a NPDES site. One sample at NPDES8 exceeded the manganese standard. This value, 3.62 mg/1, is most likely an outlier. Historic data for this site displays an average value of 0.2 mg/l and a previous maximum value of 0.91 mg/l. One sample from SSC10 (lower Cow Camp Creek) exceeded the chronic selenium standard, 4.6 ug/l, with a valued of 4.8 ug/l, but not the acute standard, 18.4 ug/1. One sample from NPDES4 experienced an exceedance of the sulfide standard (0.002 mg/l un-ionized) this year. The analytical method available to SCC detects both dissolved sulfides and acid-soluble metallic sulfides present in suspended matter. It is suspected that a large portion of the sulfides detected is of the latter type, which would bias the un-ionized results high. Any dissolved sulfides present in surface water should eventually oxidize to sulfates. In September 2003, the CDPHE resegmented Grassy Creek from Yampa Segment 12 to Segment 13e. Regulation 33 was further revised in December 2005 and August 2008. Table 13 shows the new CDPHE receiving stream standards 19