I have found two links for the Bureau of Indian Affairs
Some of the addresses I might be able to get the boundry data from follow:
Portland Area Office
(Oregon, Washington, and Idaho)
Bureau of Indian Affairs
Marion Peterson-Coordinator
911 N.E. 11th Avenue
Portland, Oregon 97232
(503)231-6702 FAX (503) 231-2201
Department of the Interior
Bureau of Indian Affairs
Office of Public Affairs,
1849 C Street NW
Washington DC, 20240-0001
Office (202) 208-3711 FAX (202) 501-1516
Northern Idaho Agency
Bureau of Indian Affairs
P.O. Drawer 277
Lapwai, ID 83540
P: 208/843-2300
F: 208/843-7142
William Aubertin (Acting)
Plummer Field Office
Bureau of Indian Affairs
Agency Road
Plummer, ID 83851
P: 208/686-1277
F: 208/686-1903
Michael A. Morigeau, Field Representative