Columbia Basin Project were built at the north and south ends of Grand Coulee, the dry canyon south of Grand Coulee Dam, allowing the coulee to be filled with water pumped up from the Columbia River. The resulting reservoir, called Banks Lake, is about long. Banks Lake serves as the CBP's initial storage reservoir. Additional canals, siphons, and reservoirs were built south of Bank Lake, reaching over . Water is lifted from Lake Roosevelt to feed the massive network. The total amount of the Columbia flow that is diverted into the CBP at Grand Coulee varies a little from year to year, and
Grand Coulee Dam to oversee the dam project, and Reclamation was selected to oversee construction. On July 16, 1933, a crowd of 3,000 watched the driving of the first stake at the low dam site, and excavation soon began. Core drilling commenced that September while the Bureau of Reclamation accelerated its studies and designs for the dam. It would still help control floods and provide for irrigation and hydroelectricity, though at a reduced capacity. Most importantly, it would not raise its reservoir high enough to irrigate the plateau around the Grand Coulee. However, the dam's design provided for future raising and upgrading. Before