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YSSF2. In both instances the total recoverable iron at the Yoast Mine outfalls met the Segment <br /> Be iron standard and the concentration were an order of magnitude lower than the <br /> concentrations observed downstream (Table 17). This indicates that the elevated iron in Sage <br /> Creek during these events was unrelated to the runoff from the reclaimed mine and further <br /> demonstrates that iron concentrations above the standard in Sage Creek can occur naturally as a <br /> result of erosion from the unaffected portion of the watershed. <br /> Ammonia, Nitrogen <br /> The Yampa Segment Be ammonia nitrogen water quality standard of 0.05 mg/L was exceeded <br /> once at YSSF3 and once at YSS2 (Table 7 and Table 8). The aquatic life ammonia standard, as <br /> established by USEPA, is dependent on both the pH and temperature of the surface water body. <br /> The ammonia in the YSSF3 (0.07 mg/L) and YSS2 (0.11 mg/L) samples were compared to the <br /> temperature and pH dependent values of the chronic criterion found in Table 6 of USEPA's 2013 <br /> Aquatic Life Ambient Water Quality Criteria for Ammonia—Freshwater(USEPA 2013). The <br /> ammonia chronic aquatic life criteria value is 3.3 mg/L for the YSSF3 sample and 0.74 mg/L for <br /> the YSS2 samples.Neither of the samples exceed the chronic aquatic life criteria value. <br /> Sulfide <br /> As discussed in greater detail in the Grassy Creek Sulfide section, the sulfide detection limit for <br /> the method utilized by SCC's lab exceeds the instream water quality standard. The analytical <br /> method detects both dissolved sulfides and acid-soluble metallic sulfides that are present in <br /> suspended matter and provides a single cumulative concentration that includes both the ionized <br /> (HS-) and un-ionized forms of hydrogen sulfide (H2S). The un-ionized hydrogen sulfide is the <br /> potentially toxic form that the instream water quality standard was established for. Calculations <br /> of the un-ionized H2S indicate that the alkaline surface water at this location will not result in <br /> un-ionized H2S above the water quality standard when the sulfide concentrations are below 0.02 <br /> mg/L.None of the samples collected from stream points YSSF3 or YSS2 exceed the 0.02 mg/L <br /> concentration. <br /> SL-7 - 40 <br />