The Winema National Forest is a national forest in Klamath County on the eastern slopes of the Cascades in south-central Oregon and covers . The forest borders Crater Lake National Park near the crest of the Cascades and stretches eastward into the Klamath Basin. Near the floor of the basin the forest gives way to vast marshes and meadows associated with Upper Klamath Lake and the Williamson River drainage. To the north and east, extensive stands of ponderosa and lodgepole pine grow on deep pumice and ash that blanketed the area during the eruption of Mount Mazama nearly 7,000 years ago. A 1993 Forest Service study estimated that the extent of old growth (economic definition) in the forest was .