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-43- <br />Both the 81ue Ribbon and the Somerset mines have surface facilities <br />and underground mine workings located in the Hubbard Creek <br />Drainage. The combined mining operations of the Blue Ribbon and <br />Somerset mines may impact the quality of surface water flowing in <br />Hubbard Creek and in the irrigation ditches supplied by Hubbard <br />Creek. The quantity of flow may be depleted through the dewatering <br />of faults, fractures and rock strata which are in direct or in <br />indirect communication with the alluvium or stream bottom of <br />Hubbard Creek. <br />The Somerset Mine has mined beneath Hubbard Creek. Inspection of <br />the underground workings by CMLRD hydrologists showed this portion <br />of the mine to be making significant amounts of water. At the <br />present time it is uncertain whether or not surface flows are being <br />depleted. However, there is a greater concentration of inflows and <br />increased discharges associated with the inflow in the Somerset <br />mine workings below Hubbard Creek. <br />The Mt. Gunnison application has proposed a subsidence protection <br />plan for the Dry Fork of Minnesota Creek to protect streamflow. <br />The adequacy of this protection plan was not assessed as a part of <br />the Mt. Gunnison Mine permit review (this area lies outside of the <br />current 5-year permit area). The Division stipulated that <br />site-specific monitoring data concerning subsidence and its <br />hydrologic effects be taken into account in the design of any <br />protection plan. <br />Three perennial streams cross the southern portion of the Mt. <br />Gunnison life-of-mine area: Lick Creek, South Prong, and Horse <br />Creek. Subsidence effects could be significant along these stream <br />courses as well, unless WECC develops and institutes subsidence <br />protection plans for these drainages as well as Dry Fork. <br />Depletion of Seeps and Springs <br />Underground mining, even in the absence of subsidence, could cause <br />flow from intermittent and perennial springs to be depleted, or <br />even to go completely dry. The significance of this effect depends <br />upon the use of the spring water and its contribution to flow in <br />receiving streams. <br />Underground mining at the Mt. Gunnison Mine has a high potential <br />for affecting springs located in Sylvester Gulch. However, flow <br />from these springs is already diverted into the Tony Bear Pipeline <br />for use in the Bear mining operation, and does not reach the North <br />Fork of the Gunnison. <br />The Mt. Gunnison permit application identified numerous springs in <br />or adjacent to the area to be mined. The application indicates <br />that springs contribute 11 percent of the flow in Lower Dry Fork, 4 <br />percent of the flow in Lick Creek, 12.6 percent of the flow in <br />