Middle Santiam Wilderness, Wilderness area in Willamette National Forest, Oregon.

Middle Santiam Wilderness is a 30 km² (about 7,400-acre) protected area in Willamette National Forest, in the central Cascade Range of Oregon. Its terrain runs from steep slopes and ridges down to bench-like lower ground. Donaca Lake, the Middle Santiam River and Chimney Peak, a 4,965-foot lava plug in the northwest, are its main features.

Congress protected this territory in 1984 as a designated wilderness area within the Cascade Range system. The decision reflected growing efforts to preserve unaltered landscapes across the Pacific Northwest.

The name comes from the Middle Santiam River, which flows through the area and gives the wilderness its identity. The river and Donaca Lake support native fish, and Chinook salmon return to spawn there each season. Visitors can watch for salmon in the water while walking the river corridor.

Access is by unmarked trails that require navigation skills and proper gear for backcountry travel. Be prepared for uneven terrain, dense vegetation, and weather that changes quickly in the mountains.

Chimney Peak, a lava plug in the northwestern part of the wilderness, is the highest point at 4,965 feet. The Middle Santiam Wilderness covers about 30 km2, and Menagerie Wilderness lies not far to the south.