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the lower canyon reaches because the sediment supply originates from the DeerlodgePark reach. Sand deposition occurs in the pools upstream of the cobble riffles during low flow and is scoured during the high spring flows. Some sand deposition occurs on the cobble bars and riffles during the peak flows (O'Brien 1984) . It was observed during the 1983 peak flow that portions of the cobble bars and riffles were covered by 0.15 m or more of sand. At low flow, this sand deposition affected the discharge distribution around bars. High flows on the recessional limb were required to flush sand from the interstices of cobbles (O'Brien 1984). The dynamics of removing the sand from the cobbles involving the incipient motion of the cobbles is discussed in Harvey et al.( 1993). Generally, the flushing of sand from the cobbles without cobble mobilization is limited to a depth equivalent to the median coarse particle diameter (O'Brien 1984; Berry 1985). The cobble bars in Yampa Canyon in the vicinity of RK 26-29 were used as spawning habitat by Colorado pikeminnow (Tyus 1990). The 8 km Deerlodge Park sand-bed reach is an important indicator of the dynamic relationship between the sediment load in the Little Snake River and dominant discharge of the Yampa River (Table 5). Upstream of the confluence of the two rivers, the Yampa River has cobble substrate. Immediately downstream of the confluence, the river is primarily sand-bed with a few exposed cobble and gravel bars. The sediment transport capacity of the Deerlodge Park reach controls the sediment load to Yampa Canyon. Deerlodge Park serves as a sediment storage reach. Sediment may build-up in this reach over several years then a large slug of sand enters the canyon during high flows. Elliott et al. (1984) concluded that the Deerlodge Park reach was in sediment transport equilibrium, Le., that neither aggradation or degradation were 26