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<br />units of concentration (mg/1 or ug/1) for each parameter. The units <br />used for each parameter are the same as those listed on the standards <br />table (Table 9) and are also the same as those used in the water quality <br />reports. The frequency column on Table 10. indicates the number of <br />exceedences out of the total number of samples (i.e.,. 1/2 indicates one <br />exceedence out of two samples) . Below is a summary of standards that <br />were, exceeded. Given in parenthesis is the source and use of each <br />standard. Although the CDOH does not indicate between livestock and <br />irrigation uses in their surface water agricultural standards, they have <br />done so in their similar ground water agricultural standards (see Table <br />5). For the sake of discussion, ~SCC chooses to use those ground water <br />use standards classifications (livestock or irrigation) for surface <br />water use evaluation. <br />Parameter ~ Number of Sites <br />manganese" (CDOH irrigation) 7 <br />nickel (CDOH irrigation) 1' <br />Review of this summary indica tes that only two CDOH surface water <br />agricultural use standards were exceeded . Nickel was exceeded at Spoil <br />Spring 6 (SSSPG6). However, this water is substantially diluted before <br />it leaves the permit boundary (notice no exceedences at lower Grassy <br />Creek (SSG2)). The manganese standard was exceeded at seven sites. <br />However, as noted previously in the ground water discussion, the <br />relatively low CDOH standard of 0•.2 mg/1, according to the EPA, applies <br />to plants grown in acidic soils. In alkaline soils, as are found in the <br />Seneca II region, a more appropriate (EPA) standard would be 10 mg/1. <br />The maximum manganese value observed this year at any NPDES outfall was <br />0.66 mg/1 at NPDES 003. All stream sites had manganese values less than <br />0.5 mg/1. It should also be noted that the site on Grassy Creek (SSG1) <br />that is upstream of Seneca II discharges also experienced exceedences of <br />the 0.2 mg/1 standard. <br />Water discharged from the Seneca II Mine is not used directly for <br />irrigation. Indirectly, although, water discharged from the mine is . <br />significantly diluted by water from either Fish Creek or the Yampa River <br />20 <br />