The Castle Rock Wilderness Study Area (WSA) (OR-3-18) is located in Malheur County, Oregon, approximately 26 miles north of the community of Juntura and U.S. Highway 20. The WSA includes 5,560 acres of BLM lands and 640 acres of split-estate lands. The WSA is roughly triangular in shape and has three narrow extensions which give it a slightly irregular perimeter. It is bounded by a combination of high standard dirt roads on public land and by private property. Most of the southern and southwestern boundary borders private land. Portions of the area are steep and support stands of ponderosa pine with Douglas fir, western juniper and mountain mahogany. The most notable physical feature of the WSA is Castle Rock. It is the highest within 100 miles to the south and east and 20 miles to the north and west. Castle Rock is the neck of an extinct volcano and reaches an elevation of 6,780 feet.
The WSA was initially identified and studied under section 603 of the Federal Land Policy and Management Act (FLPMA) with additional acquired estate lands studied under section 202. The WSA was included in the Final Oregon Wilderness Environmental Impact Statement (EIS) filed in February 1990.