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The iron excursion was the result of high suspended solids. Two samples <br />from YSG5 exceeded the total recoverable iron standard of 1.0 mg/l with <br />values of 1.07 and 2.53 mg/l in 2016. No excursions occurred at NPDES <br />sites. <br />No sites exceeded the sulfide standard this year. The sulfide values <br />provided in Tables 13, 15 and 17 in Appendix A differ from the values <br />reported in Appendix D. The sulfide data presented in Appendix D are the <br />total of both the ionized (S-) and un -ionized (H2S) forms of hydrogen <br />sulfide. The un -ionized form is the potentially toxic form, and is what <br />the CDPHE water quality standard is based upon. A procedure for <br />calculating the un -ionized form may be found on the website: <br />http://www.mullalyengineering.com.au/images/product/file/45/Problem of H <br />ydrogen Sulphide in Sewers.pdf page 5, Table 1. The analytical method <br />detects both dissolved sulfides and acid -soluble metallic sulfides <br />present in suspended matter. It is suspected that a large portion of the <br />sulfides detected is of the latter type, which would bias the un -ionized <br />results high. Any dissolved sulfides present in surface water should <br />eventually oxidize to sulfates. <br />No sites exceeded the ammonia standard this year. The aquatic life <br />ammonia standard is dependent on pH and temperature. The detection limit <br />for ammonia is 0.05 mg/1. All values above detection limit are compared <br />to table standards, page 87, fund on this website: <br />http://nepis.epa.gov/Adobe/PDF 20003O3L. df <br />The drinking water standard for mercury is 2 ug/l. The aquatic life <br />standard for mercury is 0.01 ug/1, 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 of 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 thee was no reasonable potential for PSCM's outfa�onger <br />ls to <br />exceed the mercury limit; therefore, mercury monitoring is no <br />required for PSCM's outfalls. <br />22 <br />