2012-04-27_REPORT - C2009087 (2)

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Parameter # of Sites / # of Excursions Cadmium (CDPHE irrigation) 1/1 Manganese (CDPHE irrigation) 6/6 Nickel (CDPHE irrigation) 1/1 Selenium (CDPHE irrigation) 1/1 This summary indicates that only four CDPHE surface water agricultural use standards were exceeded. The manganese standard was exceeded at six sites. However, as indicated in the recently revised CDPHE Regulation 31, the standard of 0.2 mg /l, applies to plants grown in acidic ( <6.0 pH) soils. In alkaline soils, as are found in the PSCM region, a more appropriate (EPA) standard would be 10 mg /l. The maximum manganese value observed this year at any NPDES outfall was 0.461 mg /l at NPDES3. All stream sites had manganese values less than 1 mg /l, and all but one spoil springs were less than 10 mg /1. It should also be noted that the site on Grassy Creek (SSG1) that is upstream of PSCM and Seneca II discharges has often experienced exceedances of the 0.2 mg /l standard. Spoil Spring 6 exceeded the cadmium, nickel and manganese agricultural standards. However, this spring eventually flow into Spoil Spring 6A and NPDES Pond 002, neither of which exceeded any of these parameters. Spoil Spring 4 exceeded the selenium standard. This spring has previously never exceeded the standard. Table 12 shows the CDPHE receiving stream standards for Fish Creek (Yampa Segment 13b). Table 13 provides a comparison of those standards to water quality data collected this year from NPDES4 and Site SSC10 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 upper portion of the tributary that NPDES4 discharge into. Standards that were exceeded are: Parameter # of Sites / # of Excursions Selenium 1/2 17