Glacial Lake Columbia Glacial Lake Columbia Glacial Lake Columbia was the lake formed on the ice-dammed Columbia River behind the Okanogan lobe of the Cordilleran Ice Sheet when the lobe covered of the Waterville Plateau west of Grand Coulee in central Washington state during the Wisconsin glaciation. Lake Columbia was a substantially larger version of the modern-day lake behind the Grand Coulee Dam. Lake Columbia's overflow – the diverted Columbia River – drained first through Foster Coulee, and as the ice dam grew, through first Moses Coulee, and finally, the Grand Coulee. The Cordilleran ice sheet also blocked the Clark Fork River and
Grand Coulee Dam Clapp were pumpers, while many influential businessmen in Spokane associated with the Washington Water and Power Company (WWPC) were staunch ditchers. The pumpers argued that hydroelectricity from the dam could cover costs and claimed the ditchers sought to maintain a monopoly on electric power. The ditchers took several steps to ensure support for their proposals. In 1921, WWPC secured a preliminary permit to build a dam at Kettle Falls, about upstream from the Grand Coulee. If built, the Kettle Falls Dam would have lain in the path of the Grand Coulee Dam's reservoir, essentially blocking its construction. WWPC planted rumors