2018-06-29_PERMIT FILE - C1981025

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During the permanent cessation phase of the operation the surface water monitoring was reduced. Monitoring of pond discharges is done according to requirements of CDPS permit number CO -048233. Monitoring on upper and lower North Thompson Creek was reduced to biannual quality monitoring in May and September according to the following parameters: Total Dissolved Solids pH Calcium Iron Manganese Sulfate Copper (mine seepage only) Total Suspended Solids Bicarbonate Chloride Magnesium Sodium Zinc Monitoring of North Thompson Creek was initiated to determine if the mine site and mine discharges impacted the water quality in North Thompson Creek. There has never been an identified impact to North Thompson Creek. Since the mine site has been reclaimed and there is no mine discharge that flows into the Creek, impacts will continue to be minimal to non- existent. Therefore, beginning in June 2018, the North Thompson Creek monitoring will be suspended. The discharge from the No. 1 Mine water treatment ponds (Outfall 001) will be sampled and analyzed annually in June if the discharge flows into North Thompson Creek. June 1989 was the date of the first required sample. The sample will be analyzed for the same parameters listed above for North Thompson Creek including an additional parameter which is copper. The flumes on North and Middle Thompson Creek were removed in the summer of 1986 and flow measurements have been discontinued. All other monitoring on Middle Thompson Creek will be discontinued. Monitoring on the Roaring Fork River was discontinued in previous revisions the permit. 3.6.1.4 Alternative Water Supply The only known use of ground water within the permit area and adjacent areas was by the North Thompson Creek Mine. The mine's water supply was provided by water pumped from the underground workings. This water was appropriated under rights purchased from Anschutz Corporation. The mining operation did not divert or use the surface water from North Thompson Creek. The North Thompson Creek Mine filled during 1988. Since that time, all of the water that flows into the mine, flows out and is passed through treatment ponds. This water is discharged back into North Thompson Creek or contained in on site ponds during most of the year. Seasonally from April through November, a small amount of this water, (10 gpm +/-), is pumped upslope for use for agriculture and stock watering. The only consumptive use of the mine water is storage and seasonal use. At any time this use could be curtailed. Therefore if there were a "call" on North Thompson Creek, all of the mine water would be returned to the creek through the treatment ponds. Since there is no ongoing need for the mine water, no alternative water supply is necessary. TR -29 3-86 04/18