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This summary indicates that only two of the CDPHE surface water <br />agricultural use standards were exceeded. The manganese standard was <br />exceeded at four sites and the selenium standard was exceeded at one <br />site. However, as indicated in the recently revised CDPHE Regulation 31, <br />the standard of 0.2 mg/l or selenium applies to plants grown in acidic <br />(<6.0 pH) soils. In alkaline soils, as are found in the PSCM region, a <br />more appropriate (EPA) standard would be 10 mg/1. All sites had <br />manganese values less than 1 mg/1. It should also be noted that the site <br />on Grassy Creek (SSG1) that is upstream of PSCM discharges has often <br />experienced exceedances of the 0.2 mg/l standard. <br />Table 12 in Appendix A shows the CDPHE receiving stream standards for <br />Fish Creek (Yampa Segment 13g). This new segment came into effect <br />December 31, 2014. Table 13 in Appendix A provides a comparison of <br />those standards to water quality data collected this year from NPDES4 <br />and Site SSC10 in the Fish Creek basin. The stream standards for Fish <br />Creek are based on aquatic life standards, even though there are no fish <br />present in the upper portion of the tributary that NPDES4 discharge <br />into. Standards that were exceeded are: <br />Parameter # of Sites / # of Excursions <br />Mercury 1/1 <br />The mercury MDL is 0.20 ug/1. All test values this year were less than <br />t e MDL. The mercury standard is 0.01 ug/1. <br />T ble 14 in Appendix A shows the CDPHE receivi g stream standards for <br />Upper Grassy Creek (Yampa Segment 13). This new segment came into effect <br />December 31, 2014. Table 15 in Appendix A provides a comparison of <br />those standards to water quality data collected this year from NPDES and <br />stream sites in the Grassy Creek basin. Standards that were exceeded <br />are: <br />