Grand Coulee Dam on the Columbia River in Washington was built from 1933 to 1942 to generate hydroelectric power and deliver irrigation water to the Columbia Basin, after a long struggle over how to irrigate central Washington. Backed by promoters including William M. Clapp, James O'Sullivan, and Rufus Woods, the high-dam design won federal approval in 1935 after Franklin D. Roosevelt endorsed it. The massive project became the largest power station in the United States by nameplate capacity and later expanded with a third powerhouse. Its electricity fueled wartime industry and its reservoir supports vast irrigation, but it also displaced thousands, flooded Native lands and burial sites, and blocked salmon from the upper river.