What is the Columbia River?

The Columbia River is a major Pacific river that originates at Columbia Lake in southeastern British Columbia, flows about 800 kilometres in Canada and another 1,200 kilometres in the United States to its mouth on the Pacific Ocean at Astoria, Oregon. The total river length is about 2,000 kilometres, the fourth-longest river in North America. The Columbia drains a basin of about 670,000 square kilometres, including parts of British Columbia, Washington, Oregon, Idaho, Montana, and several other US states.

The Canadian Columbia flows north-northwest from Columbia Lake (elevation 813 metres) through the Rocky Mountain Trench to Mica Creek, then south through Kinbasket Lake (the reservoir above Mica Dam) to Revelstoke. The river then turns west into Arrow Lakes Reservoir (Upper and Lower Arrow Lakes are now a single reservoir) and south through Castlegar to cross the Canada-US border at Patterson, BC. Major tributaries in Canada include the Kicking Horse, Beaver, Spillimacheen, Kootenay, and Pend d'Oreille Rivers. The Big Bend of the Columbia (where the river turns from north-flowing to south-flowing) is one of the most distinctive features of BC geography.

The Columbia River was central to the 1846 Oregon Treaty, which fixed the Canada-United States border at the 49th parallel west of the Continental Divide and gave Britain (later Canada) the headwaters of the Columbia in modern southeastern British Columbia. The Treaty replaced earlier proposals to use the Columbia River itself as the boundary. The 1961 Columbia River Treaty between Canada and the United States (in force from 1964) regulated flood control and hydroelectric generation. Three Canadian dams built under the Treaty (Mica, Duncan, and Keenleyside) and the Libby Dam in Montana fundamentally altered the river's flow regime.

The Canadian Columbia supports significant hydroelectric generation. BC Hydro's Mica Dam (1,805 megawatts), Revelstoke Dam (2,480 megawatts), and Hugh L. Keenleyside Dam (185 megawatts) produce a substantial fraction of British Columbia's electricity. Renegotiation of the Columbia River Treaty has been a major Canada-US bilateral file since 2013, with the original Treaty's core provisions due to expire in 2024 unless modernised. The Indigenous Nations Council of the Sinixt (Lakes Salish, previously declared 'extinct' by the federal government in 1956 but re-recognised in the Supreme Court Desautel decision of 2021), the Ktunaxa Nation, and the Secwepemc Nation hold Aboriginal title and treaty interests in the Canadian Columbia basin.