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revised in December 2005. Table 13 shows the new CDOH receiving stream . <br />standards for Grassy Creek. Table 14 provides a comparison of those <br />standards to water quality data collected this year from NPDES and <br />stream sit es in the Grassy Creek basin. Standards that were exceeded <br />are: <br />Parameter # of Sites / # of Excursions <br />Iron, Total Rec. 3/4 <br />Sulfide 5/5 <br />All iron excursions were the result of high suspended solids. None of <br />the iron excursions were at a NPDES site. Two of the three stream sites <br />that experienced excursions are upstream of Seneca's discharges. <br />Five samples experienced exceedances of the sulfide standard (0.002 mg/1 <br />un-ionized). Two of these excursions are from streams above Seneca's <br />discharges . The analytical method available to SCC detects both <br />dissolved sulfides and acid-soluble metallic sulfides present in <br />suspended matter. It is suspected that a large portion of the sulfides <br />detected i s of the latter type, which would bias the un-ionized results <br />high. Any dissolved sulfides present in surface water should eventually <br />oxidize to sulfates. <br />NPDES Effluent Criteria (Permit No. CO-0000221). Three excursions of <br />NPDES effluent criteria occurred this year. NPDES3 experienced an <br />excursion of the total suspended solids limit, 3S mg/1, on June 7 with a <br />value of 36 mg/1. The excursion was a result of an algae bloom. This <br />site was in compliance for all months after the excursion. <br />Both NPDES4 and NPDESS failed the chronic WET tests for fathead minnows <br />performed in July. Preliminary Toxicity Investigations for both sites <br />passed the limits, indicating that the toxic episode was transitory (or <br />may have never existed in the first place, i.e. lab error). <br />Surface Water Summary. Water discharged from the Seneca II Mine is not <br />used directly for irrigation. Indirectly, although, water discharged <br />22 <br />