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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 14. <br />Site Date H2S+HS,mg/1 ~H ~H2S H25 concentration, mg/1 <br />SSG3 4/13/04 0.03 7.96 9.0 0.003 A <br />SSLGS 4/13/04 0.04 9.00 1.0 0.0004 <br />A = exceedence <br />Only one sample experienced exceedences of the sulfide standard. This <br />site drains a pre-SMCRA mining area- However, any sulfides present in <br />surface water should eventually oxidize to sulfates. <br />NPDES Effluent Criteria (Permit No. CO-0000221). No excursions of <br />NPDES effluent criteria occurred this year. <br />• <br />Surface Water Summary. Water discharged from the Seneca II Mine is not <br />used directly for irrigation. Indirectly, although, water discharged <br />from the mine is significantly diluted by water from either Fish Creek <br />or the Yampa River before it is diverted and used for irrigation. No <br />irrigation exists on Grassy Creek below Seneca II. Due to the relative <br />amount of dilution by additional water from both sources, the ambient <br />water qualities of Fish Creek and the Yampa River are the dominant <br />factors in determining their suitability for irrigation. Water <br />discharged from the Seneca II Mine is, however, used for livestock <br />watering. <br />Below average rainfall and snowfall values resulted in below average <br />discharge values this year. TDS values at NPDES 002 and 003 are <br />increasing at a moderate rate while TDS values at NPD ES 004 and 008 are <br />increasing slightly and appear to be stabilizing. On lower Grassy Creek <br />(SSG2), TDS values are increasing slightly. Of the ten spoil springs <br />monitored, seven are exhibiting decreasing EC trends, while two display • <br />a stable EC trend. Discharges are normally suitable for livestock, but <br />24 <br />