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, Washington 100 females age 18 and over, there were 80.5 males. The median income for a household in the city was $21,818, and the median income for a family was $29,375. Males had a median income of $25,625 versus $18,125 for females. The per capita income for the city was $13,639. About 11.7% of families and 19.3% of the population were below the poverty line, including 25.3% of those under age 18 and 17.6% of those age 65 or over. Grand Coulee, Washington Grand Coulee is a city in Grant County, Washington, United States. The population was 988 at the 2010