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Probable Hydrologic Consequences <br />According to data supplied by the USGS, the annual seven day minimum flow for <br />the North Fork of the Gunnison River is 25 cfs. This low flow value occurred February <br />17, 1978, is for the period of record from 1934 through 1995 and is measured upstream <br />of the Town of Somerset, CO. <br />The maximum outcrop seepage discharged from the treatment pond during the <br />year was 10.6 gpm with a maximum TDS of 3700. In order to account for additional <br />seepage not intercepted by the treatment pond, it will be assumed a total of 50 gpm is <br />seeping from the outcrop. <br />The PHC section of the permit projects the total flow through the alluvium is 136 <br />gpm. Of that total flow, approximately 41 gpm is subject to contamination from the coal <br />stockpile area. The quality of the contaminated water should be similar to the water <br />quality in well AA-1. For the period of 1987 though 2002, the maximum TDS measured <br />in AA-1 was 3630 in 2002. <br />The maximum TDS measurement at the upstream North Fork of the Gunnison <br />River monitoring station during 2004 was 140 mg/I in August. The following table <br />presents the estimated affect the mine discharge and alluvial flow will have on the <br />quality of water in the North Fork of the Gunnison River: <br />PHC North Fork of the Gunnsion River <br /> Flow m Flow cfs TDS <br />North Fork 11,220 25.0 140 <br />Mine See a e 50 0.11 3700 <br />Alluvial Flow 41 0.09 3630 <br /> <br />Combined Flow 11311 25.2 168 <br />-9- <br />