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from NPDES and stream sites in those basins. Standards that were exceeded <br />are: <br />Parameter <br /># of Sites / # of Excursions <br />Iron, Total Recoverable (TR) 2/4 <br />Mercury, Total 3/3 <br />Selenium, Pot. Dissolved 1/1 <br />Selenium, Total Recoverable (TR) 1/1 <br />The total recoverable iron standard (1.0 mg/1) was exceeded four times at <br />two sites this year (YSGFS and YSGS) with a high of 2.64 mg/l. Iron <br />excursions were likely the result of high suspended solids (TSS) and are <br />generally observed during snowmelt runoff. This strict aquatic life <br />standard was exceeded in over half of the pre -mining stream samples. <br />The drinking water standard for mercury is 2 ug/1. 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 runs two different mercury tests, a high level <br />test with a MDL of 0.2 ug/l (for streams) and a low level test with a MDL <br />of 0.0002 ug/l (for certain NPDES sites only). All high level test values <br />this year were less than the detection limit, which is 0.2 ug/l. <br />NPDESI3 exceeded the selenium Yampa Segment 13e standard, 4.6 ug/1 chronic <br />and 18.4 ug/1 acute, with values of 18.3 ug/1 (potentially dissolved) and <br />18.8 ug/l (total recoverable). Both exceedances were from a sole sample <br />on April 4, 2017. NPDESI3 did not exceed the selenium agricultural use <br />standard of 20 ug/l. <br />NPDES Effluent Criteria (Permit No. CO -0000221) <br />No excursions of NPDES limits occurred this year. <br />14 <br />