The Willamette National Forest is a National Forest located in the central portion of the Cascade Range of US state of Oregon. It comprises 1,678,031 acres (6,790.75 km2) making it one of the largest national forests. Over 380,000 acres (694 mi2, 1,540 km2) are designated wilderness which include seven major mountain peaks. There are also several National Wild and Scenic Rivers within the forest. The forest is named for the Willamette River, which has its headwaters in the forest. The forest headquarters are located in the city of Eugene. There are local ranger district offices in McKenzie Bridge, Mill City, Detroit, Sweet Home, and Westfir.
The forest is famous for being at the center of the controversy between the logging industry and the endangered species status of the Northern Spotted Owl.Environmentalists maintain that the forest was aggressively clear-cut for many years threatening a federally listed endangered species. The timber industry contends that the forest can simultaneously provide lumber jobs and wildlife habitat. Since April 1994, the forest is governed by the Northwest Forest Plan, which restrict, but does not eliminate, logging in potential spotted owl habitat. Despite protest, the forest is still heavily logged and a drive through the region shows many recent clear-cuts.
The forest stretches for over 100 miles (160 km) along the western slopes of the Cascade Range in Western Oregon. It extends from the Mount Jefferson area east of Salem to the Calapooya Ridge which divides the watersheds of the Willamette and Umpqua rivers. Most of the forest (about 61%) is located in Lane County, but there are large areas in Linn, Marion, and Douglas counties, as well as much smaller areas in Clackamas and Jefferson counties.
The elevation of the forest ranges from about 1,500 feet (460 m) above sea level on the western edge of the forest to almost 10,500 feet (3,200 m) at the top of Mount Jefferson, Oregon's second highest peak. Seven major peaks of the Cascades—Mount Jefferson, Mount Washington, Three Fingered Jack, Diamond Peak, North, Middle and South Sisters—as well as numerous high mountain lakes are within these wilderness areas. The McKenzie River and the North Fork Middle Fork Willamette River are Wild and Scenic rivers.
The Willamette National Forest receives 80 to 150 inches (2,000 to 3,800 mm) of precipitation each year from moist onshore Pacific Ocean flow which encounters adiabatic cooling rising over the Cascades. Much of the precipitation is received in the form of snow which accumulates in higher elevations from October through April. The rain and snow melt drain into the McKenzie, Santiam, and Willamette rivers, which flow from the forest and provide high-quality drinking water to Eugene, Salem, Corvallis, and Albany. There are over 1,500 miles (2,400 km) of rivers and streams in the forest and over 375 lakes.
The forest's dominant tree species is the Douglas-fir, the state tree of Oregon. Douglas-fir is a valuable timber species in the United States. The forest contains some stands of old-growth forest, some of which are over 300 feet (90 m) tall, among the tallest trees in the World, with tree diameters ranging from three to eight feet (0.9 to 2.4 m). A 1993 Forest Service study estimated that the extent of old growth in the forest was 594,800 acres (240,700 ha).
Over one dozen other conifer species are common on the forest, including Western Redcedar, Incense-cedar, Western White Pine, Ponderosa Pine, Pacific Yew, Western Hemlock, Mountain Hemlock, and several species of Fir. The Willamette National Forest is home to over 300 species of fish and wildlife, including the northern spotted owl, Northern Bald Eagle, Chinook salmon, Bull trout, Southern Red-backed Vole, Wolverine, and several other sensitive and threatened species.
About one fifth, or 380,805 acres (1,541 km2), of the Willamette National Forest is designated as wilderness area, some of which conserve its old-growth forests:
- Diamond Peak Wilderness at 52,337 acres (212 km2) is mostly located within the Deschutes National Forest
- Middle Santiam Wilderness at 8,542 acres (35 km2)
- Menagerie Wilderness at 5,033 acres (20 km2)
- Mount Jefferson Wilderness at 111,177 acres (450 km2) is partially located within the Mount Hood and Deschutes National Forests
- Mount Washington Wilderness at 52,516 acres (213 km2) is partially located within the Deschutes National Forest
- Opal Creek Wilderness at 20,266 acres (82 km2)
- Three Sisters Wilderness at 242,400 acres (981 km2) is partially located within the Deschutes National Forest
- Waldo Lake Wilderness at 37,162 acres (150 km2)