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<br /> <br />According to data supplied by the USGS, the annual seven day minimum flow for the <br />North Fork of the Gunnison River is 25 cfs. This low Flow value occurred February 17, 1978, is <br />for the period of record from 1934 through 1995 and is measured upstream of the Town of <br />Somerset, CO. <br />The mine water discharge initially flowed at approximately 20 gpm. As of April 1998, the <br />flow has increased to about 35 gpm. In order to account for additional outcrop flow from the <br />flooded mine, it will be assumed that the mine water flow equals 50 gpm. The maximum <br />measured TDS value for the mine water has been 4090 mg/I. <br />The PHC section of the permit projects the total flow through the alluvium is 136 gpm. <br />Of that total flow, approximately 41 gpm is subject to contamination from the coal stockpile area. <br />The quality of the contaminated water should be similar to the water quality in well AA-l. For <br />the period of 1987 though 1996, the maximum TDS measured in AA-1 was 2890 in 1995. <br />The maximum TDS measurement at the upstream North Fork of the Gunnison River <br />monitoring station during 1997 was 120 mg/I. The following table presents the estimated affect <br />the mine discharge and alluvial flow will have on the quality of water in the North Fork of the <br />Gunnison River: <br />Probable Avdrologic Consequences <br />PHC North Fork of the Gunnsson River <br /> Flow m Flow cfs TDS <br />North Fork 11,220 25 120 <br />Mine Dischar a 50 0.11 4090 <br />Alluvial Flow 41 0.09 2890 <br /> <br />Combined Flow 11 311 25.20 148 <br />C~ <br />