1993-11-15_PERMIT FILE - C1981017 (2)

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Mid-Continent Report; Nov. 15, 1993 Steve Renner/Harry Posey Page 9 Driving of the 'Rock Tunnel' adit in 1984 led to changes in mining practices in ways that caused TSS to fall. How this happened might be discerned from a review of the mining practices over that period. The adit apparently became operational in 1987, according to the 1988 AHR. Road use probably decreased, and the combination of decreased road use and installation of sediment collection ponds likely caused TSS concentrations to fall. There is no discernable indication that flooding of the adit and the subsequent "natural' discharge caused deterioration of water quality by Dissolved Solids beyond that caused by the prior pumped discharges. However, there does appear to be an excursion toward poorer TDS quality water after the adit was constructed and in operation. Higher dissolved solids appear to consist of Na and Ca sulfates and dissolved clays, as deduced from the pre-existing water quality information and the known composition of the local rocks. Overall, water quality from the mine area has improved in some respects but has deteriorated in others. Unless the adit intersected base metal sulfide veins that are now weathering and contributing to poor water quality (high TDS) it is highly unlikely that the parameters that have lowered the water quality are of the type that would injure wildlife. It would be appropriate to collect water quality monitoring samples at station #20 over the next year, analyze them for a full suite of base metals, and from that determine whether the mine water discharge is of a different composition than that of the general water quality prior to construction of the adit. cc: Mike Long Jim Pendleton Larry Routten Tony Waldron Attachments: The Crystal River Drainage Study August 1978 - May 1979 USGS Multiple station analyses (Processed 11-10-93) Water quality data excerpts; Mid-Continent Annual Hydro Reps. Graphs showing flow, TDS, TSS, and Conductivity