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<br />u <br /> <br />Probable Hvdrolo~ic Consequences <br />According to data supplied by the USGS, the annual seven day minimum flow for the <br />NoRh 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 maximum mine water discharge during the year was 40.9 gpm. In order to account <br />for additional outcrop Flow from the flooded mine, it will be assumed the mine water flow equals <br />50 gpm. The maximum measured TDS value for the mine water during the year was 3650 mg/1. <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 <br />area. The quality of the contaminated water should be similar to the water quality in well AA-1. <br />For 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 Iv'orth Fork of the Gunnison River <br />monitoring station during 1998 was 60 mg/1. The following table presents the estimated affect <br />the mine discharge and alluvial tlow will have on the quality of water in the North Fork of the <br />Gunnison River: <br />PHC North Fork of the Gunnsion River <br /> Flow m Flow cfs TDS <br />North Fork 11,220 25 60 <br />Mine Discharge 50 0.11 3650 <br />Alluvial Flow 41 0.09 2890 <br /> <br />Combined Flow 1 ],311 25.20 86 <br />-11- <br />