History of the National Park Service and multi purpose river basin development programs like the Tennessee Valley Authority which began in the 1930s and spread to river valleys in all parts of the country after World War II. Lake Mead was the first National Recreation Area. The Boulder Canyon Project Act, passed in 1928, authorized the Bureau of Reclamation to construct Hoover Dam on the Colorado River. Work began in 1931 and the dam, highest in the Western Hemisphere, was completed in 1935. The next year, under provisions of an agreement with the Bureau of Reclamation, the National Park Service assumed responsibility for all recreational activities
Floods in the United States: 1901–2000 which was recorded at on July 1. The Colorado, which is usually dry at the mouth due to extensive diversions, reached the Gulf of California for the first time since the 1960s. Due to a spillway design error at Glen Canyon coupled with the relentless flooding, the dam at Glen Canyon very nearly failed, which would have emptied Lake Powell (the second-largest man-made lake in the US) and flooded out the entire lower valley of the Colorado River, cutting off water supplies to millions of people. By August as the water finally began to recede, the dam held, though only