The Columbia Basin, the drainage basin

Drainage basin

A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...

 of the Columbia River

Columbia River

The Columbia River is the largest river in the Pacific Northwest region of North America. The river rises in the Rocky Mountains of British Columbia, Canada, flows northwest and then south into the U.S. state of Washington, then turns west to form most of the border between Washington and the state...

, occupies a large area–about 673396 square kilometres (259,999.6 sq mi)—of the Pacific Northwest

Pacific Northwest

The Pacific Northwest is a region in northwestern North America, bounded by the Pacific Ocean to the west and, loosely, by the Rocky Mountains on the east. Definitions of the region vary and there is no commonly agreed upon boundary, even among Pacific Northwesterners. A common concept of the...

 region of North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

. In common usage, the term often refers to a smaller area, generally the portion of the drainage basin that lies within eastern Washington

Eastern Washington

Eastern Washington is the portion of the U.S. state of Washington east of the Cascade Range. The region contains the city of Spokane , the Tri-Cities, the Columbia River and the Grand Coulee Dam, the Hanford Nuclear Reservation and the fertile farmlands of the Yakima Valley and the...

.

Usage of the term "Columbia Basin" in British Columbia generally refers only to the immediate basins of the Columbia and Kootenay River

Kootenay River

The Kootenay is a major river in southeastern British Columbia, Canada and the northern part of the U.S. states of Montana and Idaho. It is one of the uppermost major tributaries of the Columbia River, which is the largest North American river that empties into the Pacific Ocean...

s and excludes that of the Okanagan, Kettle

Kettle River

-Rivers:*Kettle River in British Columbia and Washington*Kettle River , a tributary of the St. Croix River in eastern Minnesota*Kettle River , a tributary of the Blueberry River in central Minnesota...

 and Similkameen River

Similkameen River

The Similkameen River runs through southern British Columbia, eventually discharging into the Okanogan River near Oroville, Washington in the United States. The river is approximately long, and its drainage basin is in area...

s.

Description

The Columbia Basin includes the southeastern portion of the Canadian

Canada

Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

 province of British Columbia

British Columbia

British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...

, most of the U.S. state

U.S. state

A U.S. state is any one of the 50 federated states of the United States of America that share sovereignty with the federal government. Because of this shared sovereignty, an American is a citizen both of the federal entity and of his or her state of domicile. Four states use the official title of...

s of Idaho

Idaho

Idaho is a state in the Rocky Mountain area of the United States. The state's largest city and capital is Boise. Residents are called "Idahoans". Idaho was admitted to the Union on July 3, 1890, as the 43rd state....

, Oregon

Oregon

Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...

, and Washington, the western part of Montana

Montana

Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...

, and very small portions of Nevada

Nevada

Nevada is a state in the western, mountain west, and southwestern regions of the United States. With an area of and a population of about 2.7 million, it is the 7th-largest and 35th-most populous state. Over two-thirds of Nevada's people live in the Las Vegas metropolitan area, which contains its...

, Utah

Utah

Utah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...

, and Wyoming

Wyoming

Wyoming is a state in the mountain region of the Western United States. The western two thirds of the state is covered mostly with the mountain ranges and rangelands in the foothills of the Eastern Rocky Mountains, while the eastern third of the state is high elevation prairie known as the High...

. The south and southeastern drainage divide

Water divide

A drainage divide, water divide, divide or watershed is the line separating neighbouring drainage basins...

 borders the interior drainage of the northern Great Basin

Great Basin

The Great Basin is the largest area of contiguous endorheic watersheds in North America and is noted for its arid conditions and Basin and Range topography that varies from the North American low point at Badwater Basin to the highest point of the contiguous United States, less than away at the...

. To the northeast the region borders the basins of the Saskatchewan River

Saskatchewan River

The Saskatchewan River is a major river in Canada, approximately long, flowing roughly eastward across Saskatchewan and Manitoba to empty into Lake Winnipeg...

 (Hudson Bay

Hudson Bay

Hudson Bay , sometimes called Hudson's Bay, is a large body of saltwater in northeastern Canada. It drains a very large area, about , that includes parts of Ontario, Quebec, Saskatchewan, Alberta, most of Manitoba, southeastern Nunavut, as well as parts of North Dakota, South Dakota, Minnesota,...

) and the MacKenzie River

Mackenzie River

The Mackenzie River is the largest river system in Canada. It flows through a vast, isolated region of forest and tundra entirely within the country's Northwest Territories, although its many tributaries reach into four other Canadian provinces and territories...

 (Beaufort Sea

Beaufort Sea

The Beaufort Sea is a marginal sea of the Arctic Ocean, located north of the Northwest Territories, the Yukon, and Alaska, west of Canada's Arctic islands. The sea is named after hydrographer Sir Francis Beaufort...

), and to the northwest the basin of the Fraser River

Fraser River

The Fraser River is the longest river within British Columbia, Canada, rising at Fraser Pass near Mount Robson in the Rocky Mountains and flowing for , into the Strait of Georgia at the city of Vancouver. It is the tenth longest river in Canada...

. The Columbia Basin extends from the Rocky Mountains

Rocky Mountains

The Rocky Mountains are a major mountain range in western North America. The Rocky Mountains stretch more than from the northernmost part of British Columbia, in western Canada, to New Mexico, in the southwestern United States...

 in the east through the Cascade Range

Cascade Range

The Cascade Range is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as the North Cascades, and the notable volcanoes known as the High Cascades...

 to the Columbia River's outflow at the Pacific Ocean

Pacific Ocean

The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

 in the west.

The Columbia River pours more water into the Pacific Ocean than any other river in North or South America. In its 1270 miles (2,043.9 km) course to the Pacific Ocean, the Columbia flows through four mountain ranges—the Rockies

Rocky Mountains

The Rocky Mountains are a major mountain range in western North America. The Rocky Mountains stretch more than from the northernmost part of British Columbia, in western Canada, to New Mexico, in the southwestern United States...

, Selkirks

Selkirk Mountains

The Selkirk Mountains are a mountain range spanning the northern portion of the Idaho Panhandle, eastern Washington, and southeastern British Columbia. They begin at Mica Peak near Coeur d'Alene, Idaho and extend approximately 320 km north from the border. The range is bounded on its west,...

, Cascades

Cascade Range

The Cascade Range is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as the North Cascades, and the notable volcanoes known as the High Cascades...

, and coastal mountains—and drains 258000 mi2. The mainstem of the Columbia rises in Columbia Lake

Columbia Lake

Columbia Lake is the primary lake at the headwaters of the Columbia River, in British Columbia, Canada. It is fed by several small tributaries. The village of Canal Flats is located at the south end of the lake....

 on the west slope of the Rocky Mountain Range in Canada. Its largest tributary, the Snake

Snake River

The Snake is a major river of the greater Pacific Northwest in the United States. At long, it is the largest tributary of the Columbia River, the largest North American river that empties into the Pacific Ocean...

, travels 1038 miles (1,670.5 km) from its source in Yellowstone National Park

Yellowstone National Park

Yellowstone National Park, established by the U.S. Congress and signed into law by President Ulysses S. Grant on March 1, 1872, is a national park located primarily in the U.S. state of Wyoming, although it also extends into Montana and Idaho...

 in Wyoming before joining the Columbia. When Lewis and Clark explored the region in the early 19th century, huge numbers of fish (salmon

Salmon

Salmon is the common name for several species of fish in the family Salmonidae. Several other fish in the same family are called trout; the difference is often said to be that salmon migrate and trout are resident, but this distinction does not strictly hold true...

) returned to spawn every year. "The multitudes of this fish are almost inconceivable," Clark wrote in the autumn of 1805. At that time, the Columbia and its tributaries provided 12935 miles (20,816.8 km) of pristine river habitat.

Common usage

Residents of the area surrounding the confluence of the Columbia

Columbia River

The Columbia River is the largest river in the Pacific Northwest region of North America. The river rises in the Rocky Mountains of British Columbia, Canada, flows northwest and then south into the U.S. state of Washington, then turns west to form most of the border between Washington and the state...

 and Snake

Snake River

The Snake is a major river of the greater Pacific Northwest in the United States. At long, it is the largest tributary of the Columbia River, the largest North American river that empties into the Pacific Ocean...

 rivers—a region centering on the Tri-Cities, Washington

Tri-Cities, Washington

The Tri-Cities is a mid-sized metropolitan area in the southeastern part of the U.S. state of Washington, consisting of three neighboring cities: Kennewick, Pasco, and Richland. The cities are located at the confluence of the Yakima, Snake, and Columbia rivers in the semi-arid region of...

 metropolitan area—use the term "Columbia Basin" to refer to their own, much smaller region. This usage is roughly synonymous with the Columbia Plateau

Columbia Plateau

The Columbia Plateau is a geologic and geographic region that lies across parts of the U.S. states of Washington, Oregon, and Idaho. It is a wide flood basalt plateau between the Cascade Range and the Rocky Mountains, cut through by the Columbia River...

 or roughly equivalent to the relatively unforested area bounded by the Cascades, Blue

Blue Mountains (Oregon)

The Blue Mountains are a mountain range in the western United States, located largely in northeastern Oregon and stretching into southeastern Washington...

, Wallowa

Wallowa Mountains

The Wallowa Mountains are a mountain range located in the Columbia Plateau of northeastern Oregon in the United States. The range runs approximately 40 mi northwest to southeast in southwestern Wallowa County between the Blue Mountains to the west and the Snake River to the east. The range is...

, and Rocky

Rocky Mountains

The Rocky Mountains are a major mountain range in western North America. The Rocky Mountains stretch more than from the northernmost part of British Columbia, in western Canada, to New Mexico, in the southwestern United States...

 mountain ranges and the Okanagan Highland

Okanagan Highland

The Okanagan Highland is a plateau-like hilly area in British Columbia, Canada, and the U.S. state of Washington . It lies between the Okanagan Valley on its west and the Kettle River on its east, and geologically is more or less an extension of the Thompson Plateau, which lies west of the Okanagan...

. This sense of the term Columbia Basin has expanded from its early focus on the land irrigated by Grand Coulee Dam and the Columbia Basin Project to include other irrigation districts such as the Yakima and Walla Walla valleys. At its center is the Pasco Basin, an area roughly double the size of, and fully containing, the Hanford Site

Hanford Site

The Hanford Site is a mostly decommissioned nuclear production complex on the Columbia River in the U.S. state of Washington, operated by the United States federal government. The site has been known by many names, including Hanford Works, Hanford Engineer Works or HEW, Hanford Nuclear Reservation...

.

External links

• Geology of Washington - Columbia Basin, Washington State Department of Natural Resources