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Parameter <br />Ammonia Nitrogen <br />Iron, Total Recoverable (TR) <br />Mercury <br />Sulfide <br /># of Sites / # of Excursions <br />The aquatic life ammonia standard is dependent on pH and temperature. <br />The detection limit for ammonia is 0.05 mg/l. All values above detection <br />limit are compared to table standards found on this website, page 87: <br />http://www.epa.gov/waterscience/criteria/ammonia/99update.pdf <br />No ammonia excursions occurred this year. <br />Iron excursions were likely the result of high -suspended solids (TSS) <br />and are generally observed during snowmelt runoff. This strict aquatic <br />life standard (1.11 mg/1) was exceeded in over half of the pre -mining <br />stream samples. <br />The drinking water standard for mercury is 2 ug/l. The aquatic life <br />standard for mercury is 0.01 ug/l, which is set to protect the average <br />human consumer of fish. SCC's lab uses a method with a detection limit <br />of 0.2 ug/l. None of the samples collected this year were above the <br />detection limit. During the last NPDES permit renewal, the CDPHE <br />performed a reasonable potential analysis on SCC's outfalls. It <br />determined that there was no reasonable potential for SCC's outfalls to <br />exceed the mercury limit; therefore, mercury monitoring is no longer <br />required for SCC's outfalls. <br />One sample from site WSPG46 experienced an exceedance of the sulfide <br />standard, 0.02 mg/l, this year with a value of 0.07 mg/l. 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. Any dissolved sulfides present in surface water should eventually <br />oxidize to sulfates. <br />24 <br />