When Grand Coulee Dam was being built during the depths of the Great Depression, everything about it was the biggest in the world. The mile-long behemoth was the largest hydroelectric power-producing facility in the world and was completed just in time to power the nation's defense plants and the atomic reactors for the Manhattan Project. But despite its tremendous achievements –including the plentiful production of clean energy - the negative consequences of its construction are equally noteworthy. In a single stroke, Grand Coulee prevented access to one of the greatest salmon rivers in the world, threatening huge populations of fish with extinction, depriving the local Native people of their most important economic and spiritual resource. This AMERICAN EXPERIENCE film explores how the crucial tension between technological achievement and environmental impact hangs over the project's legacy.