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<br /> <br />Parameter # of Sites / # of Excursions <br />Iron, Total Rec. 4/11 <br />Nitrite 2/2 <br />Selenium 2/5 <br />Sulfide 2/2 <br />The total recoverable iron standard (1.0 mg/1) was exceeded eleven times <br />this year. Excursions were normally related to high suspended solids. <br />The two NPDES site excursions occurred during snowmelt runoff in April. <br />This strict aquatic life standard was exceeded in 38% of the premining <br />stream samples. Two samples also exceeded the nitrite standard. Nitrites <br />are unstable in aerated water (Hem, 1989), and will oxidize to nitrates. <br />Five samples from two sites exceeded the chronic selenium standard, 4.6 <br />ug/1. The acute standard, 18.4 ug/1, was not exceeded. <br />Two samples from two sites experienced exceedances of the sulfide <br />standard (0.002 mg/1 un-ionized) this year. These excursions occurred <br />during snowmelt when suspended solid concentrations are high. The <br />analytical method available to SCC detects both dissolved sulfides and <br />acid-soluble metallic sulfides present in suspended matter. It is <br />suspected that a large portion of the sulfides detected is of the latter <br />type, which would bias the un-ionized results high. Any dissolved <br />sulfides present in surface water should eventually oxidize to sulfates. <br />The stream standards for Segment 13e discussed above are based on <br />aquatic life standards, even though there are no fish present in the <br />upper portions of these drainages. SCC has proposed to the CDPHE that <br />these stream standards be changed to agricultural standards. A decision <br />regarding this will be made in June 2008 at a hearing for the Upper <br />Colorado River Basin. <br />NPDES Effluent Criteria (Permit No. CO-0000221). One excursion of NPDES <br />effluent criteria occurred this year. The excursions occurred at Pond <br />014. A sample collected on April 2 had a TSS value of 42 mg/l. The <br />13 <br />1 - - <br />__ -- <br />