Hells Canyon Dam on the Snake River, at river mile 247.5, is located 23 miles downstream from Oxbow Dam. Hells Canyon Dam was the third and final dam built for the Complex.  It began generating electricity in 1967.  It houses three generating units with a total nameplate capacity of 391 megawatts (MW). Hells Canyon Dam is unique in that the switchyard is mounted on the dam's face.