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<br />Colorado Yampa Coal Company (CYCC) hereby submits an analysis of stream- <br />flow depletion of the Upper Colorado River Basin (UCRB) due to surface mining <br />activities at tf~ CYCC mine. This submittal is made in order to comply with <br />new regulations,. the "lJindy Gap Policy", of the United States Fish and Wild- <br />life Service (USFWS). <br />CYCC is a surface coal mine seven miles northwest of Oak Creek, Colorado, <br />in Routt County. The mine impacts Fish, Foidel and Middle Creeks, which are <br />headwater streams within the Upper Colorado River Basin. <br />Separate streamflow depletion analyses have been conducted for (1) all <br />mining activity authorized by CYCC Permit 79-117 at Mines 1, 2 and Eckman <br />Park, and (2) mining associated only with Lease 26914, which is a newly leased <br />30 acre tract. Information regarding the hydrology of the area under consi- <br />deration and impact of mining activity can be found in Permit 79-117, which <br />was submitted to the Colorado Mined Land Reclamation Division in 1979. Speci- <br />fic information used in this analysis is taken from the Permit. The life of <br />Mines 1, 2 and the Eckman Park i4ine is from 1979 to 1987. <br />Mines 1, 2 and Eckman Park <br />Mining under Permit 74-177 impacts surface water quantity in the UCRB <br />through (1) construction of sedimentation ponds; and (2) use of water for <br />operations and dust control. <br />Two types of ponds have been considered for this analysis: ponds which <br />dry up during the summer and ponds which do not. Each pond contains an outlet <br />works whose lowest orifice i5 located at the elevation of designed sediment <br />volume. Sediment is cleaned out of each pond when sediment reaches 60% of <br />designed sediment volume. Water levels generally remain at or below the <br />lowest outlet orifice except during spring snowmelt. Most ponds receive <br />little runoff after snowmelt. This observation is borne out by the fact that <br />from 1975 to 1978, Foidel Creek (U.S.G.S. Station 9243900) experienced over <br />97~ of total runoff in t4arch through i4ay. Thus, many ponds completely evapor- <br />ate by autumn. Evaporation for these ponds has been estimated as equal to the <br />-1- <br />