How Wide is the Columbia River at Its Widest Point?


Written by Janet F. Murray

Updated: July 20, 2023

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Infographic about the Columbia River.
The Columbia River is the world’s greatest source of hydroelectric power.

The Columbia River has a width of 6 miles near its mouth. This location is near the Astoria-Megler Bridge. It lies over the lower part of the Columbia River between Astoria, Oregon, and Megler, Washington.

The Columbia River is North America’s Pacific Northwest’s most prominent. It is also the fourth-largest river in the U.S. by volume. Additionally, it has the greatest flow of any North American river entering the Pacific Ocean.

Follow us as we explore the magnificent and unique Columbia River.

How Does the Width of the Columbia River Vary Along Its Flow?

The Columbia River is approximately 14 miles at its widest point near the Astoria-Megler Bridge.


The width of the Columbia River varies considerably along its 1,243-mile flow. It twists and turns from British Columbia through seven U.S. states. Then, it dumps its massive load into the Pacific Ocean.

This river also varies from one to 14 miles wide between Oregon and Washington alone. Here are some examples of the variations in width to give you a clearer idea of just how much its breadth changes:

  • Astoria-Megler Bridge – 14 miles
  • Lewis and Clark Bridge – 2,722 feet
  • Vancouver-Portland Bridge – 3,538 feet
  • Bonneville Lock and Dam – 2,690 feet
  • Bridge of the Gods – 1,856 feet
  • Hood River Bridge – 4,418 feet
  • The Dalles Bridge – 3,339 feet
  • Biggs Rapids Bridge – 2,567 feet
  • John Day Dam – 7,635 feet
  • Umatilla Bridge – 3,433 feet
  • McNary Dam – 7,365 feet

Where is the Mouth of the Columbia River Located on a Map?

The mouth of the Columbia River is located in the Pacific Northwest region of the United States, on the border between Oregon and Washington. It can be found at approximately 46 degrees north latitude and 124 degrees west longitude. To get there by car, one can take Highway 101 or Interstate 5 and follow signs to Astoria, Oregon, or Long Beach Peninsula in Washington state. The river mouth itself is where the Columbia River meets the ocean, forming a wide estuary that stretches for several miles along the coast. On a map, it can be identified as a large body of water with multiple channels leading inland toward Portland, Oregon, and other cities along its banks.

How Large is the Columbia Basin?


The Columbia

River Basin

is the size of France.

©Kmusser / CC BY-SA 3.0 – Original / License

Incredibly, the Columbia River has a drainage basin the size of France. It covers 258,000 square miles of waterways and lakes. Further, it supports 14 hydroelectric dams on its journey. Also, this mighty river and its tributaries account for about 219,000 square miles of drainage. This drainage covers one Canadian province and seven U.S. states:

  • Idaho
  • Montana
  • Wyoming
  • Utah
  • Nevada
  • Oregon
  • Washington
  • The Canadian province of British Columbia

The basin’s unique relationships between topography, hydrologic cycles, and human innovation have been the source of much provision. For example, this basin offers the following resources:

  • Precious metals
  • Fertile soils
  • Abundant forests
  • Clean, renewable, low cost and reliable electricity
  • Flood control
  • Irrigation
  • Navigation
  • Recreation

How Many Tributaries Feed Into this River?

Amazingly, more than 60 significant tributaries and smaller ones feed into the Columbia River. Furthermore, six primary river systems form part of the Columbia River.

Five sub-tributaries are the longest to feed the Columbia River. We categorize them from longest to shortest below:

  1. Snake River System – 1,078 miles
  2. Kootenay River System – 485 miles
  3. Deschutes River System – 252 miles
  4. Yakima River System – 214 miles
  5. Willamette River System – 187 miles

Four of the six sub-tributaries are the largest by discharge volume. We categorize these from highest to lowest below:

  1. Snake – 54,830 cubic feet per second at Ice Harbor Dam
  2. Willamette – 33,010 cubic feet at the Morrison Bridge in downtown Portland
  3. Kootenay – 27,616 cubic feet at Cora Linn Dam near Nelson, British Columbia
  4. Pend Oreille – 26,320 cubic feet at Box Canyon Dam in northern Washington

Why Does the Columbia River Have the Greatest Flow in North America?

Columbia River emits the 36th most voluminous discharge of all the world’s rivers.

© Kukanur

And because of its unique flow, Columbia has one of the greatest runoffs in the world. From its headwaters in British Columbia to its abrupt exit into the Pacific, the river drops at about two feet per mile.

This lofty decent causes the Columbia River to empty an enormous 192 million cubic feet of water into the Pacific annually.

Measured by the volume of its flow, the Columbia is the largest river flowing into the Pacific from North America. In fact, Columbia has the 36th greatest discharge of any river in the world.

Why is the Mouth of the Columbia River Dangerous?

Columbia River Mouth

The Columbia Bar is murky and dangerous.

©Little Mountain 5 / CC BY-SA 3.0 – Original / License

The waters of the Columbia can be dangerous and tempestuous at their destination. Because of its downhill flow through mountain ranges, its arrival at the mouth can be dramatic. And the Columbia approaches the ocean at full force. Combined with an abrupt drop and a steep incline to the sea bottom at the Astoria, it causes a watery riot.

Additionally, the Columbia picks up desert sand, volcanic ash, and forest debris along its path. This debris creates an ellipse of mucky sludge at the mouth, forming what is known as the Columbia River bar. The river and ocean fight fiercely over the bar shoving the debris back and forth.

A quote from World’s Most Dangerous by Michael Haglund sums up the situation exceptionally well, “… The Columbia River bar is the most dangerous entrance to a commercial waterway in the world.”

How Does the Columbia River Basin Facilitate Hydropower?

Despite its explosive nature, the Columbia River is an ideal source of renewable, low-cost, reliable electricity. Hydroelectric dams supplied by the Columbia River and its major tributaries produce half of the electricity consumed in the Pacific Northwest.

A harmonious balance between high volume flow and stable canyons makes the Columbia River an ideal power source. Currently, 14 of the 450 dams in the Columbia River basins are used for electricity. 

Why Are There Efforts To Clean up the Columbia River?

Fresh-caught steelhead trout on stones with lure in its mouth


and steelhead – a legacy of the Columbia River.


Besides, the Columbia River is home to many fish species. Important ones include the anadromous (migrating) fish. Examples of these are the lamprey, salmon, steelhead, shad, and sturgeon. However, the steelhead and salmon are famous residents of this river. These fish have been a vital part of the river’s ecology and lifeblood of the Pacific Northwest for hundreds of years.

Unfortunately, industry and waste by-products have caused harm to the river’s ecosystem. So, the ‘taming’ of the Columbia River for people has often caused conflict with conservation. Now, several organizations are working toward its clean-up and attempting to restore environmental balance to the long, wide Columbia River.

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About the Author

I'm a freelance writer with more than eight years of content creation experience. My content writing covers diverse genres, and I have a business degree. I am also the proud author of my memoir, My Sub-Lyme Life. This work details the effects of living with undiagnosed infections like rickettsia (like Lyme). By sharing this story, I wish to give others hope and courage in overcoming their life challenges. In my downtime, I value spending time with friends and family.

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