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• Water Oualitv <br />The quality of the water in the area of the Colowyo Mine has been rated as poor by <br />the USGS and designated for limited agricultural use. Since USGS testing in 1978, <br />no water quality analysis performed at monitoring points at the Colowyo Mine have <br />shown any significant difference in water quality compared with what the initial <br />USGS work. The water is slightly saline, alkaline and definitely classified as `hard' <br />water. This can be seen in the water quality measurements for total dissolved solids <br />(TDS) and electrical conductivity (eC). Both TDS and eC exceed the EPA secondary <br />drinking water standards. <br />Since the water is alkaline, the pH is above 7, but rarely exceeding 8.4. <br />Concentrations of heavy metals rarely exceed health limits, as stated in the USGS <br />report. This has also been backed up by the shallow ground water monitoring <br />performed since the Colowyo Mine began operation. <br />Conclusions <br />The Colowyo Mine has no single or multiple continuous geologic units in the mine <br />that contains ground water under unconfined or conftned conditions. The only <br />ground water encountered is the discontinuous perched pockets of ground water. <br />This lack of ground water, except for discontinuous perched ground water pockets, <br />encountered during mining precludes the necessity to monitor ground water on a <br />ridge top. <br />U <br />n <br />U <br />4.05-9c Revision Date: 11/17/05 <br />Revision No.: MR-75 <br />