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I <br />Discharges from the Edna Mine have not exceeded the greater than 0.03 mg/1 instream standards for <br />these constituents. Edna's samples usually contain less than 0.01 mg/l of these two constituents. <br />Comparison of sample data from Trout Creek surface water sites TR-B (upstream from the Moffat Pond <br />discharge) and TR-C (downstream from the Moffat Pond discharge) indicates the Moffat Pond and/or <br />spoil springs in this area probably contribute a significant sulfate load to Trout Creek water. The <br />increase in sulfate concentration between these two locations is usually more than 50%, sometimes <br />resulting in the sulfate concentration in Trout Creek exceeding the secondary drinking water standard of <br />250 mg/l, although this standard is not applicable to this segment of Trout Creek. <br />The CDPS and DRMS sample data from the Edna Mine 2002 through 2008 support a finding that the <br />mine is not causing exceedances of the instream standards. <br />Permit Requirements of Colorado Discharge Permit System (CDPS) <br />As previously mentioned, the Edna Mine has sampled discharges from two outfalls monitored under the <br />Colorado Discharge Permit System (CDPS). Sample data has been collected for the following eight <br />parameters: pH, total suspended solids, settleable solids, total recoverable iron, potentially dissolved <br />manganese, oil and grease, flow, and total dissolved solids. Sample analysis has included testing for <br />Whole Effluent Toxicity. Sample data has been reported monthly in discharge monitoring reports filed <br />with the Colorado Water Quality Control Division and DRMS. The reports indicate that for the time <br />period January 2002 through June 2009 the only exceedance of CDPS permit requirements was a single <br />exceedance of the flow limitation. <br />Clean Water Act Effluent Limitations (40 CFR Part 434) <br />Monitoring data in the Edna Mine's annual hydrology reports from 2002 through 2008 indicate the <br />mine has not caused exceedances of either limitation identified in 40 CFR Part 434 that is applicable to <br />reclamation areas on coal mines (settleable solids of 0.5 ml/l and pH of 6.0 to 9.0). <br />AVF Material Damage Suspect Levels <br />Monitoring data in the Edna Mine's annual hydrology reports from 2002 through 2008 indicate the <br />mine has not caused exceedances of the 1000 µmhos/cm level that that DRMS considers to be a <br />potential material damage threshold for irrigation water in the Trout Creek AVF during irrigation season <br />(June through September). <br />cc: Dan Hernandez <br />2