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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. PSCM's lab uses a method with a detection limit <br />of 0.2 ug/l. All the samples collected this year were below the <br />detection limit. During the last NPDES permit renewal, the CDPHE <br />performed a reasonable potential analysis on PSCM's outfalls. It <br />determined that there was no reasonable potential for PSCM's outfalls to <br />exceed the mercury limit; therefore, mercury monitoring is no longer <br />required for PSCM's outfalls. <br />NPDES Effluent Criteria (Permit No. CO -0048275). <br />An excursion occurred at Outfall 005 in June for total recoverable iron <br />exhibiting a concentration of 1367 ug/l. The 30 -day average <br />concentration limit is 1000 ug/l. No other excursions of effluent <br />limits occurred this year. <br />Surface Water Summary. <br />Water discharged from the PSCM is not used directly for irrigation. No <br />irrigation exists on Grassy Creek or Cow Camp Creek below the PSCM. <br />Indirectly, although, water discharged from the mine is significantly <br />diluted by water from either Fish Creek or the Yampa River before it is <br />diverted and used for irrigation. Due to the relative amount of dilution <br />by additional water from both sources, the ambient water qualities of <br />Fish Creek and the Yampa River are the dominant factors in determining <br />their suitability for irrigation. Water discharged from the PSCM is, <br />however, used for livestock watering. <br />Of the 15 surface water features monitored, 12 are exhibiting increasing <br />TDS trends, and three display decreasing trends. NPDES discharges are <br />normally suitable for livestock and irrigation, but exceeded water <br />quality standards (total recoverable iron) for aquatic life this year. <br />20 <br />