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Table 11 provides a comparison of all surface water quality data, <br />including the spoil spring, this year to agricultural standards. This <br />Paradox database generated table does not include the units of <br />concentration (mg /l or ug /1) for each parameter. The units used for each <br />parameter are the same as those listed on the standards table (Table 10) <br />and are also the same as those used in the water quality reports. The <br />frequency column on Table 11 indicates, in this order: uncensored, that <br />is, the number of exceedances above the Method Detection Limit (MDL) / <br />the number of exceedances between the MDL and the Practical Quantitation <br />Level (PQL) / censored, that is, the number of sample values below the <br />MDL but the MDL was higher than the standard / the total number of <br />samples. Below is a summary of standards that were exceeded. Given in <br />parenthesis is the source and use of each standard. Although the CDPHE <br />does not indicate between livestock and irrigation uses in their surface <br />water agricultural standards, they have done so in their similar ground <br />water agricultural standards (see Table 5). For the sake of discussion, <br />SCC chooses to use those ground water use standards classifications <br />(livestock or irrigation) for surface water use evaluation. <br />Parameter <br />Manganese (CDPHE irrigation) <br />Selenium (CDPHE, irrigation) <br /># of Sites / # of Excursions <br />1/2 <br />1/1 <br />This summary indicates that only two CDPHE surface water agricultural <br />use standards were exceeded. The manganese standard was exceeded twice <br />at NPDES8. However, as indicated in the recently revised CDPHE <br />Regulation 31, the standard of 0.2 mg /l, applies to plants grown in <br />acidic ( <6.0 pH) soils. In alkaline soils, as are found in the Seneca II <br />region, a more appropriate (EPA) standard would be 10 mg /l. The maximum <br />manganese value observed this year at any surface water site was 1.72 <br />mg /l. <br />NPDES8 exceeded the selenium standard (20 ug /1) with a total recoverable <br />value of 20.6 ug /l in May. Prior to this year, this site has never <br />exceeded this standard. See the following NPDES Effluent section for a <br />discussion of the selenium excursions. <br />10 <br />