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stream sites in the Grassy Creek basin. Standards that were exceeded <br />are: <br />Parameter # of Sites / # of Excursions <br />Iron, Total Rec. 1/1 <br />Mercury 1/1 <br />The iron excursion was the result of high suspended solids. YSG5 <br />exceeded the total recoverable iron standard of 1.0 mg/l with values of <br />1.60 mg/l in June. <br />The mercury MDL is 0.20 ug/1. All test values this year were less than <br />the MDL. The mercury standard is 0.01 ug/l. <br />No excursions occurred at NPDES 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 (HZS) 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, found on this website: <br />http://nepis.epa.gov/Adobe/PDF/20003O3L.pdf <br />19 <br />