Cougar Reservoir, reservoir in Lane County, Oregon, United States

Cougar Reservoir is a reservoir in the Cascade Mountains of Oregon, formed by Cougar Dam on the South Fork McKenzie River. The water is surrounded by dense forest, and several campgrounds sit along its shoreline to serve visitors who come for fishing, boating, and swimming.

Cougar Dam was built by the U.S. Army Corps of Engineers and completed in 1963, damming the South Fork McKenzie River about 3 miles south of Rainbow in Lane County. Its purposes were flood control and hydroelectric power, and the reservoir filled the valley behind the structure.

The reservoir's name comes from Cougar Dam, and its shoreline holds three Forest Service campgrounds: Cougar Crossing, Slide Creek and Sunnyside, used for camping, hiking and picnicking. Anglers fish for stocked rainbow trout and landlocked Chinook salmon, plus naturally reproducing cutthroat trout; bull trout must be released. Terwilliger Hot Springs lies along Rider Creek just west of the lake.

From Eugene, take Highway 126 east for 46 miles (74 km) to the turnoff about 3 miles (5 km) north of Rainbow, then follow the signed road south to the reservoir. The U.S. Forest Service maintains three campgrounds near the water—Cougar Crossing, Slide Creek and Sunnyside—while French Pete and Delta lie nearby. Terwilliger Hot Springs is along Rider Creek just west of the lake.

A short trail from the western shore leads to Terwilliger Hot Springs, a set of natural hot pools fed by geothermal water along Rider Creek. The pools are carved into the rock and sit in the middle of the forest, making them a completely different experience from the main reservoir visit.