Grand Coulee the Ice Age Floods. Archeological records date human presence back to nearly the end of the Ice Age, but the raging torrents erased the land of clear evidence, leaving us to question who, if anyone, may have survived. With the end of the last glacial advance, the Columbia settled into its present course. The river bed is about below the Grand Coulee. Walls of the coulee reach in height. Grand Coulee is the longest and deepest of eastern Washington canyons. Its unique characteristics include a lower floor at the head of the channel than at its outlet and the widest
Coulee Dam, Washington Coulee Dam, Washington Coulee Dam is a town in Douglas, Grant, and Okanogan counties in the State of Washington. The Douglas County portion of Coulee Dam is part of the Wenatchee–East Wenatchee Metropolitan Statistical Area. The population was 1,098 as of the 2010 census. Coulee Dam was founded by the U.S. Bureau of Reclamation in 1933, to serve as headquarters for the construction of the Grand Coulee Dam. The Okanogan County portion was known as Mason City, location of the head contractor. The Portions in Douglas and Grant Counties was known as Engineers Town and was government owned. In 1942