A bureau within the Department of the Interior, whose mission is to manage, develop, and protect water and related resources. The agency replaced the Reclamation Service, which was established pursuant to the Reclamation Act of 1902 to "reclaim (arid lands) throughout the West through irrigation." The Bureau built, operates, and maintains more than 300 storage dams on rivers throughout the western United States.

An agency in the U.S. Department of Interior, which operates federal water projects in 17 western states.

The BOR was chartered in 1902 with the responsibility to reclaim arid lands in the western U.S. for farming by providing secure, year-around water supplies for irrigation. The BOR's responsibilities since have expanded to include generating hydroelectric power; overseeing municipal and industrial water supplies, river regulation, and flood control; enhancing fish and wildlife habitats; and researching future water and energy requirements.