Lake Ewauna is a reservoir in Klamath Falls, Oregon. It is the headwaters of the Klamath River, fed by the Link River from Upper Klamath Lake. Its constant level throughout the year is controlled by the release of water from Keno Dam, 18 mi (29 km) south of the Link River's mouth on the reservoir. Dam and reservoir are elements of the Klamath River Hydroelectric Project.