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Cisco-Fish Ford (Stratum 6): The Cisco-Fish Ford reach begins below Westwater Canyon, near RKM 180, and terminates at RKM 153, about 2 km below the confluence with the Dolores River. The upper portion of this reach is bounded by shales of the Morrison Formation, while the lower portion is bounded by sandstones of the Dakota Group (Williams, 1964). Both units are easily eroded, allowing the river to form a broad alluvial valley with a distinct floodplain. Floodplain vegetation is similar to reaches upstream. The average slope is 0.00066, the bankfull width is 147 in, the bankfull depth is 4.49, and the bed material is gravel with a D50 of 38 mm (Table 1). Dewey (Stratum 5): The Dewey reach begins at RKM 151 and ends near the head of Professor Valley at RKM 140 (Fig. 1). The first few kilometers of this reach are bounded by Navaho Sandstone and Wingate Sandstone; further downstream, shales of the Cutler Formation appear at river level. Steep-walled cliffs border the river in several places, but a small, discontinuous floodplain is generally present along much of the channel, thus we classify this reach as quasi- alluvial. The average slope of the reach is 0.00047, the bankfull width is 132 m, the bankfull depth is 5.14 m, and the bed material is sand and gravel with a D50 of 34 mm (Table 1). Professor Valley (Stratum 4): Professor Valley (Fig. 1) is part of the Richardson Amphitheater, a broad valley formed as a result of uplift and differential erosion of a series of northwest-trending salt anticlines. Colman (1983) reports that uplift has been occurring in this area for at least the last 2.5 MY. A sharp inflection in the river's profile occurs just below Hittle Bottom, and the average gradient here increases to 0.00149. Professor Valley also contains several alluvial fans deposited by floods from the La Sal Mountains. Boulders from these fans now form a series of rapids. The river is bounded by shales and thinly bedded sandstones of the Cutler Formation, and Pleistocene terraces. The average bankfull width in this reach is 203 m, the bankfull depth is 4.61 in, and the bed material is gravel and cobbles with a D50 of 70 mm (Table 1). Big Bend (Stratum 3): The Big Bend reach starts below White's Rapid at RKM 124, and ends at RKM 113 (Fig. 1). The upper portion of the reach is a deeply incised canyon bounded by Wingate sandstone, a resistant bedrock unit that weathers to produce steep hillslopes mantled with talus and large boulders; a floodplain is generally absent here. The lower 6 km of the reach is bounded by the less resistant Navajo Sandstone; the canyon is somewhat wider here and a floodplain is present along one or both banks. Thick tamarisk covers the floodplain in this lower segment. The average slope of the reach is 0.00098, the bankfull width is 106 m, the bankfull depth is 6.43 m, and the average D50 is 63 mm (Table 1). Moab (Stratum 2): This reach encompasses the area upstream of Moab, UT, through the Moab Valley, from RKM 111 to RKM 105. Although this reach is short, it is unique because, here, the Colorado River goes through an abrupt transition from gravel- to sand-bed, with a corresponding decrease in channel gradient. Near Moab, the river has cut a wide alluvial valley directly across the Moab Anticline. A wide floodplain covered with dense tamarisk is present through much of the reach. The average channel gradient is 0.00034. The average bankfull width is 151 m, the bankfull depth is 5.13 m, and the bed material is gravel and sand with a D50 of 28 mm (Table 1). Potash (Stratum 1): The reach from Moab to Potash, UT marks the downstream end of the study area. This reach begins at RKM 103 and ends below the Potash plant at RKM 77 (Figure 1). The floodplain is discontinuous here, but well-developed where present. Dense thickets of tamarisk cover the floodplain in this reach. The channel is considerably wider here than upstream, with an average bankfull width of 197 m; the bankfull depth is 4.51 m, and the bed material is sand with a D50 of 0.025 mm (Table 1). 8