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Our Precious Water: The Columbia River Drainage Basin

The Columbia River drainage basin covers an area larger than the province of Alberta

In this series of educational articles, the Advance will explore connections to our water with interesting and historical facts.

So what is a drainage basin?

It is the area of land where water collects and drains off into a common source, such as a river, lake, or other body of water. Precipitation, run-off, snowmelt, streams that run on a downward slope, and groundwater underneath the surface will collect together in the basin.

Where is the Columbia River drainage basin?

In our region, the basin covers a huge area of 668,000 km2, which is larger than the entire province of Alberta! Canada and the United States share this watershed, which straddles the south-eastern corner of B.C. and the predominate chunk of the U.S. Pacific Northwest.

The footprint of the Columbia Basin includes part of B.C., most of Washington, Oregon, Idaho, a small part of Montana, and very tiny parts of Wyoming, Utah, and Nevada. It does not include any part of Alberta though, since the provincial border in southeastern B.C. runs along the continental divide. Waters on the Alberta side flow to the east, while on the B.C. side, they flow west.

The Columbia River

What starts out as tiny steams flowing in different directions, eventually forms into powerful forces, such as the Columbia River. At 2,000 km long, it is the largest river by discharge flowing into the Pacific Ocean from North America, with an average flow of 7,500 m3/s.

The Columbia River starts out between Invermere and Cranbrook in the heart of the Kootenays. From there, it heads north to Golden, then into Kinbasket Lake. It rounds the corner and heads west and south to Revelstoke, Castlegar, and Trail. Next, the water flows across the border south to the U.S. slicing through the middle of Washington state, to Portland Oregon. The river enters the Pacific Ocean just north of the city of Vancouver in Washington state.

Interestingly, the Kootenay River starts further north than the Columbia River - between Golden and Invermere. It too heads south near Cranbrook, then into Montana, and then turns north up to Creston and into Kootenay Lake. The water then flows past Nelson and down to Castlegar to merge into the Columbia.

The Columbia River also takes in waters from the Okanagan, Pend-Oreille, Snake, and Spokane rivers, just to name a few.

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