The Bonneville Dam was the first of the major dams on the Columbia River. It was one of the northwest’s largest Depression-era New Deal projects, built to harness the river’s might for hydroelectric generation and to improve navigation. Construction began in 1933, and water began to rise in 1937. In a short time, the impoundment drowned the historic Cascade rapids that had been a treacherous obstacle for Native Americans for generations and for European-American explorers and travelers since the arrival of Lewis and Clark. The dam, 2,690 feet long and 197 feet high, is about two miles downstream from the Bridge of the Gods. It is operated and maintained by the U.S. Army Corps of Engineers. There are visitor centers with interpretive programs and tours on both the Oregon and Washington sides. A separate visitor area for the navigation lock is located on the Oregon side.