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10 <br />There are no other known natural or artificial ponds or other impoundments in the XPA, <br />nor is it served or traversed by or the origin of any canals or pipelines. <br />Preliminary analysis of readily available but sparse data indicates that average flow in <br />Terror Creek peaks in May, with snow melt runoff, at between 400 and 500 cubic feet <br />per second (cfs). Flow declines rapidly to less than 50 cfs by July and averages less <br />than 12 cfs in the fall and winter months. <br />Ground Water <br />The major aquifer in the North Fork watershed is the alluvium associated with the river <br />itself, with reported yields of up to 500 gallons per minute (U.S. Department of Interior <br />1978); water quality is similar to that of the river. Perched terraces, which consist of the <br />alluvium remaining from higher Pleistocene river levels, and alluvial fans, are also <br />significant aquifers where present, especially in the vicinity of major tributaries to the <br />North Fork. Pediment and other colluvial deposits are local water sources. The <br />terraces, fans, and colluvial deposits dip gently toward the river and contain occasional <br />springs at their contact with bedrock, which dips between 2 percent and 5 percent to the <br />north and northeast. These springs are highly variable in flow rate, persistence, and <br />water quality. <br />~ The Rollins Sandstone and the numerous lenticular sandstones in the Williams Fork <br />Formation carry variable but usually small amounts of water except where strongly <br />• fractured, where flows in excess of 10 g.p.m. can occur for time periods dependent on <br />the nature of the recharge regime, if any. Because of the usually low permeability, <br />porosity, and resultant low hydraulic conductivity of these sandstones, and because <br />water quality from them is usually poor, these units are not considered aquifers in that <br />they do not store and transmit water of such quality and in sufficient quantities to be of <br />beneficial use. <br />The only probable significant aquifer in the XPA is the alluvium in the bottom of Terror <br />Creek Canyon. <br />Soils <br />The following is obtained from the Final Environmental Impact Statement, Iron Point <br />Exploration License, Iron Point Coal Lease Tract, Elk Creek Coal Lease Tract, Delta and <br />Gunnison Counties, Colorado, February 2000, formulated by the USDA-Forest Service, <br />USDI-Bureau of Land Management and USDI-Office of Surface Mining Reclamation & <br />Enforcement. <br />Soils overlying mountain side slopes and toe slopes are developing in residuum <br />and colluvium from sandstone and shale sources, as well as from some mixed <br />alluvium parent materials. <br />Soils overlying mountain side slopes and toe slopes are developing in residuum <br />and colluvium from sandstone and shale sources, as well as from some mixed <br />alluvium parent materials. These soils occur on slopes typically ranging from 20 <br />