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F: <br />• assuming all incident precipitation and snowmelt enters the alluvium, is <br />15.42 acre-feet. <br />This infiltration is 0.4 percent of the average flow through the alluvium. <br />The dilution ratio of 246:1 indicates the large dilution capability of the <br />alluvial aquifer. The actual amount of water infiltrating the Bear No. 3 <br />alluvium is much smaller than 25 inches due to evapotranspiration and the <br />fact that not all the precipitation falls on the area at the same time. <br />Assuming the precipitation and temperature patterns at Paonia, Colorado, <br />are similar to these at the Bear No. 3 Mine, it is estimated that 4.4 inches <br />of precipitation would accumulate during the winter months. This water <br />would infiltrate the alluvium under the Bear No. 3 facilities early in the <br />spring, prior to any significant amounts of evapotranspiration. Infiltration of <br />4.4 inches of water would contribute 2.71 acre-feet of water to the <br />alluvium. <br />This infiltration is 0.8 percent of the average monthly flow through the <br />alluvium. The large amount of dilution in the alluvial material will mitigate <br />any effects of contamination in the alluvium. Water quality in the <br />infiltrating water would have to be 30 times greater than background <br />concentrations to increase the concentration of any parameter by 25 <br />percent. <br />• 3. Surface Water Effects <br />Mining activities at the Bear No. 3 Mine are not expected to degrade the <br />water quality of the North Fork of the Gunnison River. The disturbed area <br />for the Bear No. 1, 2, and 3 Mines is less than 30 acres in size, and is <br />extremely small in comparison to the entire North Fork of the Gunnison <br />drainage basin. The small contribution of surface water runoff from the <br />Bear disturbed area will be diluted by flow in the North Fork of the <br />Gunnison River. The Bear No. 3 sediment pond rarely discharges, and any <br />effluent is required to meet NPDES discharge standards. <br />The water quality of the North Fork of the Gunnison River is not expected <br />to be impacted by water that infiltrates the alluvium of the Bear No. 3 <br />facilities area. The small contribution to the flow of the river is <br />insignificant. Any water which enters the alluvium will be diluted by <br />ground water flowing through the alluvium. The ground water flow through <br />the alluvium will be further diluted by the greater flow in the North Fork of <br />the Gunnison River. The average annual flow in the river is 82.3 times <br />larger than the ground water flow through the alluvium. <br />4. Conclusion <br />An assessment of the probable hydrologic consequences of the mining <br />operation and an assessment of the probable cumulative impact of all <br />• anticipated mining in the general area on the hydrologic balance has been <br />made. Pursuant to Rule 2.07.6(2)(c), the Division finds that the Bear <br />20 <br />