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<br />ClO <br />ClO <br />o <br />M <br /> <br />,~ <br />'. -.,-~ <br /> <br />Palo Verde Division (Palo Verde Diversion Dam to Taylor Ferry) <br /> <br />Except for routine maintenance and repair of constructed features, <br />channel stabilization in the Palo Verde Division is essentially <br />complete. <br /> <br />Cibola Division (Taylor Ferry to Adobe Ruins) <br /> <br />Through much of the Cibola Division, shallowness of the natural <br />channel was caused by sediment deposition. A program to correct <br />channel deficiencies by dredging and constricting levees was <br />begun in 1964 and completed in 1970. <br /> <br />Imperial Division (Adobe Ruins to Imperial Dam) <br /> <br />The Imperial Division includes a diversion pool and associated <br />backwater areas above Imperial Dam. About 50 per cent of the <br />sediment load is deposited on sandbars or in backwater lakes, <br />with the remainder diverted at Imperial Dam. Most of the diverted <br />sediment is removed by desilting works in the All-American Canal, <br />returned to the river below Imperial Dam, and dredged to perma- <br />nent dry-land storage areas. <br /> <br />Laguna Division (Imperial Dam to Laguna Dam) <br /> <br />The Laguna Division, including the empty pool behind Laguna Dam, <br />receives sediment passed by the Imperial sluice gates; and, in <br />recent years, had received large quantities of sediment returned <br />from the All-American Canal Desilting Works. Because this <br />created problems with Mexican diversions at Morelos Dam, the <br />Bureau of Reclamation constructed a settling basin in the Laguna <br />division where sediment from upstream sources is trapped and <br />pumped out for disposal on dry land. <br /> <br />Yuma Division (Laguna Dam to Morelos Dam) <br /> <br />At the present time, normal flows in this division range from <br />100 to 1000 cfs, depending on the time of year and location <br />within the division. While the historical riverbend averages <br />600 feet in width, riverflow normally occupies only about 120 <br />feet. The remaining portions of the riverbed, being at or near <br />the elevation of groundwater, support vigorous growths of vege- <br />tation (cattails, cane, arrowweed, salt cedar, mesquite, <br />cottonwood, etc.). Above Yuma, these growths are controlled by <br />complete channel reconstruction and continuing programs of <br />vegetative control (mowing or cultivation). A 1969 plan for <br />the Yuma division anticipated renovation of the low-flow channel <br />by dredging, reshaping, and lowering of the water table, plus <br />instituting a program of vegetative control. <br /> <br />D-3 <br />