Columbia River drainage basin

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

Its largest tributary, the Snake, travels 1,038 miles (1,670 km) from its source in Yellowstone National Park in Wyoming before joining the Columbia.

[2] The area includes valuable farmland that has excellent soil profile and underlying silty loess.

[1] When Lewis and Clark explored the region in the early 19th century, huge numbers of fish (salmon) returned to spawn every year.

[4] In the early 20th century, the government and private interests began constructing dams on the tributaries of the Columbia River to provide water for irrigation or flood control.