Kettle River Range Mountains, which in turn form part of the Columbia Mountains. The range runs north to south, bordered on the east by the Kettle River and the Columbia River, and on the west by the Kettle River, the Curlew Valley and the San Poil River. The mountainous region begins immediately north of the Canada–US border, at Grand Forks, British Columbia, extending 110 miles (177 km) south to the bend of the Columbia River and Lake Roosevelt, formed by Grand Coulee Dam, where it terminates. The Okanogan Highlands are adjacent to the range on the west, and the Selkirk Mountains are adjacent
Grand Coulee Dam of electricity. Each generator is supplied with water by an individual penstock. The largest of these feed the Third Powerplant and are in diameter and can supply up to . The dam's power facilities originally had an installed capacity of 1,974 MW but expansions and upgrades have increased generation to 6,809 MW installed, 7,079 MW maximum. Grand Coulee Dam generates 21 TWh of electricity annually. This means the dam generates about 2,397 MW of power on average, which results in a total plant factor efficiency of 35%. In 2014, 20.24 TWh of electricity was generated. Grand Coulee Dam's spillway is