Treaty Boundary Map
This map identifies the treaty area as compared to the diminished land area of the Confederated Tribes of the Umatilla Indian Reservation. In 1871, the Reservation boundary was surveyed for the federal government. Although the Treaty of 1855 described an area of 500,000 acres, this boundary contains only approximately 245,000 acres. The Umatilla Allotment Act (Slater Act) of 1885 authorized the allotment and diminishment of the reservation to 120,000 acres. In 1939 , a Congressional act authorizes the Secretary of Interior to restore the Umatilla Indian Reservation 14,000 acres of Federal lands located south of the diminished boundary.