Opal Creek Wilderness in Oregon’s Willamette National Forest anchors a larger protected landscape beside Mount Hood National Forest and contains the state’s largest uncut watershed. Long known for old-growth western Cascades forest, the basin once held Douglas fir, Pacific silver fir, and western hemlock commonly estimated at 500 to 1,000 years old, along with many waterfalls, lakes, and trails. Officially designated wilderness on September 30, 1996, after nearly 20 years of conflict over logging and mining, it became a landmark in Oregon conservation. That legacy was deeply altered when the Beachie Creek Fire in 2020 burned through the area and destroyed most of its old-growth forest.