Columbia River: Largest North American River Flowing to the Pacific

Columbia River: The Pacific Northwest's Mighty Artery

The Columbia River is the largest river by volume flowing into the Pacific Ocean from North America.

Vital Statistics

• Length: 1,243 mi (2,000 km).
• Basin: 258,000 sq mi (668,000 km²) – 7 US states + 1 Canadian province (BC).
• Average discharge at mouth: 265,000 cu ft/s (7,500 m³/s) – 2nd in US (after Mississippi), largest into Pacific.
• Source: Columbia Lake, BC (Rocky Mountain Trench).
• Mouth: Astoria, OR / Ilwaco, WA (Columbia Bar – "Graveyard of the Pacific").

Key Features

• 14 Mainstem Dams (US: Grand Coulee, Chief Joseph, Bonneville, The Dalles, John Day, McNary; BC: Mica, Revelstoke, Hugh Keenleyside).
• Hydropower: >40% of US hydro generation; Grand Coulee = largest US power station (6,809 MW).
• Salmon/Steelhead: Historic runs 10–16M; now 1–2M (dams, habitat loss, hatcheries).
• Irrigation: Columbia Basin Project (670K acres).
• Navigation: 465 mi slackwater to Lewiston, ID (barges: wheat, wood, fuel).
• Treaty: Columbia River Treaty (1964, US/Canada) – flood control, power sharing; modernizing 2024.

Tributaries

• Snake River (largest trib, 1,078 mi) – Hells Canyon, Shoshone Falls.
• Willamette, Deschutes, John Day, Kootenay, Pend Oreille/Clark Fork.

Bottom line: The Columbia defines the Pacific Northwest—economically, ecologically, culturally.