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-44- <br />The total estimated water consumed by all of the mines presently operating in <br />the North Fork Drainage Basin is 556 acre-feet per year. This is <br />approximately 0.14% of the mean annual yield of the river. This indicates <br />that the total coal mining activities within the North Fork of the Gunnison <br />Drainage Basin have a very minor impact on the quantity of water available in <br />the Basin. <br />Cumulative Impacts of the Blue Ribbon and Somerset Mines <br />Since all anticipated mining at the Blue Ribbon Mine is within the Hubbard <br />Creek drainage basin, the most significant cumulative impacts of all <br />anticipated mining will be the combined impacts of the Blue Ribbon Mine and <br />Somerset Mine on Hubbard Creek and on the downstream water users. <br />Data collected for the Somerset Mine estimates the annual yield in Hubbard <br />Creek to be 29,700 acre-feet per year (8% of the mean annual yield of the <br />North Fork of the Gunnison - 340,000 acre-feet per year). The total depletion <br />of the flow in Hubbard Creek due to the combined impacts of the Somerset and <br />Blue Ribbon mines may be 0.09 cfs (39 gpm or 56,160 gpd), 0.01 cfs (31 gpm or <br />44,640 gpd) coming from inflow measured in the Somerset Mine adjacent to or <br />under Hubbard Creek, and 0.02 cfs (8 gpm or 11,520 gpd) coming from withdrawal <br />of water by the Blue Ribbon Mine (this analysis ignores the pumping of mine <br />inflows back into the surface water system). This total depletion amounts to <br />about 0.18% of the average streamflow (49.3 cfs) and 3.9% of the low flow <br />(2.23 cfs) in Hubbard Creek as measured above the Blue Ribbon Mine. <br />CUMULATIVE HYDROLOGIC EFFECTS ON GROUND WATER <br />AND SURFACE WATER RESOURCES - FINDING <br />An assessment of the probable hydrologic consequences of the mining operation <br />and an assessment of the probable cumulative impact of all anticipated mining <br />in the general area on the hydrologic balance has been made. Pursuant to Rule <br />2.07.6(2)(c), the Division finds that the Mt. Gunnison mining operation has <br />been designed to prevent material damage to the hydrologic balance outside the <br />permit area. <br />