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 Coulee Dam flooded over 21,000 acres (85 km) of prime bottom land where Native Americans had been living and hunting for thousands of years, forcing the relocation of settlements and graveyards. The Office of Indian Affairs negotiated with the United States Bureau of Reclamation on behalf of tribes who were concerned about the flooding of their grave sites. The Acquisition of Indian Lands for Grand Coulee Dam, 54 Stat.703 Act of June 20, 1940 allowed the Secretary of the Interior to remove human remains to new Native American grave sites. The burial relocation project started in September 1939. Human remains