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 Dam Grand Coulee Dam (not including the Third Powerplant) to be $168 million; its actual cost was $163 million in 1943 ($ in dollars). Expenses to finish the power stations and repair design flaws with the dam throughout the 1940s and '50s added another $107 million, bringing the total cost to $270 million ($ in dollars), about 33% over estimates. The Third Powerplant was estimated to cost in 1967, but higher construction costs and labor disputes drove the project's final cost in 1973 to ($ in dollars), about 55% over estimates. Despite estimates being exceeded, the dam became an economic success,