Lake Ewauna is a reservoir in Klamath Falls, Oregon. It is the headwaters of the Klamath River, fed by 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.
Lake Ewauna is an ideal length for crew rowing, and the Ewauna Rowing Club has used the lake for practice and competition since 1970.