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Site Date NH3+NH4,mg/1 pH Temp,C $NH3 NH3 conc., mg/1 <br />No samples exceeded the ammonia standard this year. <br />Sulfide values also require extra calculations. The standard is 0.002 <br />mg/1 un-ionized H2S, while the method detects for un-ionized H2S and <br />ionized HS. The following table calculates the actual un-ionized H2S <br />concentration of the exceedences reported on Table 12. <br />Site Date H2S+HS,mg/1 pH $H2S H25 concentration, mg/1 <br />NPDES4 4/9/03 0.03 7.81 14 0.004 A <br />NPDES4 6/9/03 0.03 7.87 11.5 0.003 A <br />NPDESH 4/9/03 0.04 8.11 7.5 - 0.003 A <br />SSF11 5/21/03 0.40 8.14 7.5 0.030 A <br />SSF11 6/10/03 0.08 8.24 5.9 0.005 A <br />SSF13 5/21/03 0.40 8.16 5.9 0.024 A <br />SSF13 6/10/03 0.40 8.45 3.9 0.016 A <br />A = exc eedence <br />All samples experienced exceedences of the sulfide standard. However, <br />any sulfides present in surface water should eventually oxidize to <br />sulfates. <br />There were seven chromium values that had elevated detection limits <br />higher than the acute and chronic standards. The cause of these <br />elevated detection limits was a decision by the laboratory to dilute the <br />samples prior to analyses in order to reduce the effects of <br />interferences (primarily, high salinity). Finally, all mercury values <br />reported were less than the most sensitive available detection limit, <br />0.2 ug/1. The standard for mercury is 0.01 ug/1. <br />In 2003, the CDOH established new receiving stream standards for Grassy <br />Creek. Table 13 shows the CDOH receiving stream standards for Grassy <br />Creek (Yampa Segment 13e). Table 14 provides a comparison of those <br />standards to water quality data collected this year from NPDES and <br />22 <br />