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Along the North Fork of the Gunnison River, a narrow flood plain is <br />• restricted to a narrow V-shaped canyon. Alluvial sediments, primarily sand <br />and gravel of igneous origin, have been deposited in the flood plain. At <br />slightly higher elevations along the river canyon above the flood plain lie <br />alluvial terraces or pediments, which are the erosional remnants of ancient <br />river levels left high above the current river. <br />Several massive slump features are evident on the north-facing slopes <br />south of the North Fork of the Gunnison River. These features are the <br />result of mass movement of blocks of consolidated rock and unconsolidated <br />soil. Although it is somewhat difficult to differentiate between slumps <br />and old terraces, slumps occur primarily on moist, steep, generally north- <br />facing slopes. <br />The North Fork of the Gunnison River is part of the Colorado River <br />• system. This perennial stream is formed by the joining of Anthracite Creek <br />and Muddy Creek just downstream of Paonia Reservoir (Exhibit 2.04.5-A). <br />The Hawk's Nest Mine is approximately three miles downstream of this <br />junction. The river flows southwestward until it joins the Gunnison River <br />near Hotchkiss, Colorado. Flow is partially regulated by the Paonia <br />Reservoir upstream of the permit area on Muddy Creek. <br />The North Fork of the Gunnison River has an average annual discharge <br />of 427 cfs with a maximum recorded peak discharge of 7860 cfs (June 4, 1957) <br />at the U.S. Geological Survey (USGS) gaging station about a mile downstream <br />of the permit boundary. The same station recorded a minimum discharge of <br />17 cfs in 1951. The yearly hydrograph is snowmelt regulated. The highest <br />discharge is recorded in May due to snowmelt with a gradual decline through <br />• <br />2.04-10 <br />