established in 1849, this Cabinet department is headed by the Secretary of the Interior. The Department of the Interior functions as the major conservation agency for the federal government. Its major duties include: managing public lands, which consist of over 500 million acres; promoting the conservation, development, and use of mineral, water, fish, and wildlife resources; reclaiming arid lands for farm use; operating federal hydroelectric power facilities; administering the national parks system; and being responsible for the Native American Reservations. The bureaus and services that make up the Department of the Interior are: the National Park Service; the National Biological Survey; the Bureau of Indian Affairs; the Bureau of Land Management; the Office of Surface Mining Reclamation and Enforcement; the Minerals Management Service; the United States Fish and Wildlife Service; the Bureau of Reclamation; the United States Geological Survey; the Bureau of Reclamation; and the United States Bureau of Mines; and the Office of Territorial and International Affairs.