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
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