The DOI is a decentralized, cabinet-level agency of the federal government. It manages about one-fifth of the land area of the United States and all of the nation's Outer Continental Shelf (OCS). DOI is the nation's principal conservation agency dedicated to protecting America's treasures for future generations by providing access to our nation's natural and cultural heritage. DOI honors all trust responsibilities to American Indians, Alaska Natives, and our responsibilities to island communities. The Department's mission includes: conducting scientific research, providing wise stewardship of energy and mineral resources, fostering sound use of land and water resources, serving as the largest supplier and manager of water in 17 western states, conserving and protecting fish and wildlife, and offering recreation opportunities. Eight bureaus and each of the Departmental offices carry out the Department's missions.