Willamette River

The Willamette River is a major tributary of the Columbia River, accounting for 12 to 15 percent of the Columbia's flow. The Willamette's main stem is 187 miles (301 km) long, lying entirely in northwestern Oregon in the United States. Flowing northward between the Oregon Coast Range and the Cascade Range, the river and its tributaries form the Willamette Valley, a basin that contains two-thirds of Oregon's population, including the state capital, Salem, and the state's largest city, Portland, which surrounds the Willamette's mouth at the Columbia.

Willamette River
The Willamette passing through Downtown Portland in the 1980s
A map of the Willamette River, its drainage basin, major tributaries and major cities
Etymology	From a Clackamas Native American village name
Location
Country	United States
State	Oregon
Cities	Eugene, Corvallis, Albany, Independence, Salem, Newberg, Wilsonville, Portland
Physical characteristics
Source	Confluence of Middle Fork Willamette River and Coast Fork Willamette River
- location	near Eugene, Lane County, Oregon
- coordinates	44°01′23″N 123°01′25″W
- elevation	438 ft (134 m)
Mouth	Columbia River
- location	Portland, Multnomah County, Oregon
- coordinates	45°39′10″N 122°45′53″W
- elevation	10 ft (3.0 m)
Length	187 mi (301 km)
Basin size	11,478 sq mi (29,730 km2)
Discharge
- location	Morrison Bridge, Portland, 12.8 miles (20.6 km) from mouth
- average	33,010 cu ft/s (935 m3/s)
- minimum	4,200 cu ft/s (120 m3/s)
- maximum	420,000 cu ft/s (12,000 m3/s)
Basin features
Tributaries
- left	Coast Fork Willamette River, Long Tom River, Marys River, Luckiamute River, Yamhill River, Tualatin River
- right	Middle Fork Willamette River, McKenzie River, Calapooia River, Santiam River, Molalla River, Clackamas River

Originally created by plate tectonics about 35 million years ago and subsequently altered by volcanism and erosion, the river's drainage basin was significantly modified by the Missoula Floods at the end of the most recent ice age. Humans began living in the watershed over 10,000 years ago. There were once many tribal villages along the lower river and in the area around its mouth on the Columbia. Indigenous peoples lived throughout the upper reaches of the basin as well.

Works cited

• Bright, William (2004). Native American Placenames of the United States. Norman, Oklahoma: University of Oklahoma Press. ISBN 978-0-8061-3576-2. OCLC 53019644.