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and leffens <br /> . <br /> Water Resource, Environmental, and Mining Engineering <br /> August 29, 2018 <br /> Mr. Alan Martellaro <br /> Division 5 Engineer <br /> Colorado Dept. of Water Resources <br /> P.O. Box 396 <br /> Glenwood Springs, CO 81602 <br /> Alan.Martellaro()state.co.us <br /> Neal Misbach <br /> Lead Water Commissioner <br /> Water Districts 36, 50 and 51 <br /> 70 E Agate Unit F <br /> Granby, CO 80446 <br /> Neal.Misbach(o-)state.co.us <br /> Re: Maryland Creek Ranch Aggregate Mine near Silverthorne, Effect <br /> of Mining-Method Change on Groundwater and Substitute Water <br /> Supply Plan <br /> Gentlemen: <br /> Eagle's Nest Mountain Ranch is located across Highway 9 from Maryland Creek Ranch <br /> gravel mining operation (the Mine) about five miles north of Silverthorne. Beginning in the summer <br /> of 2016 the Mine managers changed the method of gravel/sand extraction from "wet" mining using <br /> a dragline to "dry" mining using conventional mobile equipment. The dry mining method requires <br /> pumping down (dewatering) the pit lake each spring to expose the gravel resource for conveying <br /> and screening of products. When the summer extraction season is over, the pumps are turned off <br /> and the pit refills with water. <br /> Dewatering of the gravel deposit has significantly affected the groundwater hydrology on the <br /> Eagle's Nest Mountain Ranch. Lowering of the water table during gravel extraction has affected <br /> jurisdictional wetlands and associated water pools on Eagle's Nest Mountain Ranch as well as <br /> production of hay that is irrigated by Lund Blue River Ditch. Refilling the gravel pit in late fall and <br /> winter (i.e. cessation of pumping to Maryland Creek) decreases the natural flow of groundwater to <br /> Blue River, creating a lagged out-of-priority depletion of both the Blue and Colorado Rivers. <br /> 13918 E. Mississippi Ave., #60119 <br /> Aurora. CO 80012 <br /> steffensinc(a-)-msn.com <br /> 303.378.8181 <br />