Fourmile Lake, Reservoir in Klamath County, Oregon, United States

Fourmile Lake is a reservoir in Klamath County, Oregon, at 5,748 feet elevation, 45 miles northeast of Medford and just east of Mount McLoughlin. Created by the 25-foot-tall, 660-foot-long Fourmile Lake Dam on Fourmile Creek, it covers 740 acres, reaches 170 feet deep, and borders Sky Lakes Wilderness within Winema National Forest. A campground sits near the lake.

Fourmile Lake was created in 1906 when the Fish Lake Water Company, founded in 1898 to irrigate the Rogue Valley, built a 25-foot dam on Fourmile Creek. Fish Lake was completed in 1908, and in 1915 the Cascade Canal linked the two lakes, carrying water over the Cascade Divide. The dam was repaired and a new spillway added in 1955.

The lake lies 45 miles (72 km) northeast of Medford, just east of Mount McLoughlin, at 5,748 feet (1,752 m) elevation. The Pacific Crest Trail passes about 2 miles (3.2 km) away, and a trail from the lake leads into the bordering Sky Lakes Wilderness. One campground sits near the lake; fishing, swimming and boating are the usual activities.

The lake holds rainbow trout, kokanee, brook trout and lake trout, while bushy-tailed woodrats and golden-mantled ground squirrels live around its shores. The Pacific Crest Trail passes about 2 miles (3.2 km) away, and a trail from the lake leads into the Sky Lakes Wilderness.