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A brief description of the Probable Hydrologic Consequences of the Foidel Creek Mine <br />follows: <br />Ground water <br />Several possible effects to the ground water system have been identified. <br />Dewatering and potentiometric drawdown in bedrock units <br />Dewatering will occur in the Trout Creek Sandstone, Wadge/Wolf Creek Overburden, and <br />Twentymile Sandstone. Monitoring data have verified both that this dewatering has <br />occurred and the existence of a depression of the potentiometric surfaces of these <br />hydrostratigraphic units in the vicinity of the mine. <br />Diminution of bedrock discharize to alluvium and surface streams <br />Gradient reversal due to mining could cause a decrease in natural discharge to alluvium and <br />streams. This would persist for approximately 360 years until potentiometric levels recover <br />to pre -mining conditions. Discharge of mine water discharge to the streams will more than <br />offset this loss, which is estimated at approximately .02 cfs in Fish Creek. <br />Degradation of Wadge and Wolf Creek overburden/interburden water <br />Only the Wadge and Wolf Creek overburden/interburden aquifer is predicted to be degraded <br />with regard to water quality. Estimates indicate that degraded water will persist for 23,000 <br />years. Conductivity of degraded water is estimated at 4000-7500 umhos/cm. Areas <br />immediately down gradient will be affected to a greater degree due to the close proximity to <br />the source (mine workings). Due to dilution and dispersion, water quality will generally <br />improve as the distance from the mine workings increases. Wadge and Wolf Creek <br />overburden/interburden water is not presently used on the Twentymile Park basin. <br />Degradation of alluvial water quality in Fish Creek <br />Water will move down gradient to the natural discharge points along Fish Creek. Alluvial <br />aquifers are recharged mainly by stream flows during high flow conditions and to a lesser <br />degree, bedrock discharge. Given the small amount of estimated discharge, this degraded <br />water will easily be diluted by upstream flows. <br />Degradation of alluvial water quality in Foidel Creek <br />Only the area near the confluence of Foidel and Middle Creeks contain adequate saturation <br />to be measured. As with Fish Creek, the water near the confluence of Foidel and Middle <br />Creeks will move down gradient to the natural discharge points along Middle Creek. <br />Alluvial aquifers are recharged mainly by stream flows during high flow conditions and to a <br />lesser degree, bedrock discharge. Given the small amount of estimated discharge, any <br />degraded water will easily be diluted by upstream flows. <br />Foidel Creek Mine 20 February 25, 2016 <br />