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i~ <br />Review of this summary indicates that only three CDOH surface water <br />agricultural use standard was exceeded. The manganese standard was <br />exceeded at twelve sites. However, as noted previously in the ground <br />water discussion, the relatively low CDOH standard of 0.2 mg/1, <br />according to the EPA, applies to plants grown in acidic soils. In <br />alkaline soils, as are found in the Seneca II region, a more appropriate <br />(EPA) standard would be 10 mg/1. The maximum manganese value observed <br />this year at any NPDES outfall was 0.52 mg/1 at NPDES 003. All stream <br />sites had manganese values less than 0.3 mg/l. It should also be noted <br />that the site on Grassy Creek (SSG1) that is upstream of Seneca II <br />discharges also experienced exceedences of the 0.2 mg/1 standard. <br />Spoil Spring 6 exceeded the cadmium and nickel standards for irrigation <br />(10 ug/1 and 200 ug/1) with values of 11.4 ug/1 and 310 ug/1. However, <br />this water is not used for irrigation. The National Academy of Science <br />suggests a livestock standard of 50 ug/I for cadmium and no livestock <br />standard for nickel. <br />Table 11 shows the CDOH receiving stream standards for Fish Creek (Yampa <br />Segment 13b). Table 12 provides a comparison of those standards to <br />water quality data collected this year from NPDES and stream sites in <br />the Fish Creek basin. Standards that were exceeded (excluding ammonia <br />and sulfide) are: <br />Parameter # of Sites / # of Excursions <br />Selenium (chronic) 1/1 <br />NPDESB exceeded the chronic (30 day average) selenium standard once, but <br />not the acute (one day max.) standard. <br />Ammonia values require extra calculations to determine exceedences. The <br />standard is 0.02 mg/1 un-ionized NH3, while the method detects both un- <br />ionized NH3 and ionized NH4. The following table calculates the actual <br />un-ionized NH3 concentration of the exceedences reported on Table 12. <br />21 <br />