Willamette River

major river in northwest Oregon

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
EtymologyFrom a Clackamas Native American village name[1]
CountryUnited States
CitiesEugene, Corvallis, Albany, Independence, Salem, Newberg, Wilsonville, Portland
Physical characteristics
SourceConfluence of Middle Fork Willamette River and Coast Fork Willamette River
 - locationnear Eugene, Lane County, Oregon
 - coordinates44°01′23″N 123°01′25″W / 44.02306°N 123.02361°W / 44.02306; -123.02361[2]
 - elevation438 ft (134 m)[2]
MouthColumbia River
 - locationPortland, Multnomah County, Oregon
 - coordinates45°39′10″N 122°45′53″W / 45.65278°N 122.76472°W / 45.65278; -122.76472[2]
 - elevation10 ft (3.0 m)[2]
Length187 mi (301 km)[3]
Basin size11,478 sq mi (29,730 km2)[4]
 - locationMorrison Bridge, Portland, 12.8 miles (20.6 km) from mouth
 - average33,010 cu ft/s (935 m3/s)
 - minimum4,200 cu ft/s (120 m3/s)
 - maximum420,000 cu ft/s (12,000 m3/s)
Basin features
 - leftCoast Fork Willamette River, Long Tom River, Marys River, Luckiamute River, Yamhill River, Tualatin River
 - rightMiddle 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.


  1. Bright, p. 567
  2. 2.0 2.1 2.2 2.3 [U.S. Geological Survey Geographic Names Information System: Willamette River "Willamette River"]. Geographic Names Information System. U.S. Geological Survey. November 28, 1980. Retrieved June 25, 2010. {{cite web}}: Check |url= value (help) Source and mouth elevation derived from Google Earth search using GNIS source and mouth coordinates.
  3. "Facts About the Willamette River". Willamette Riverkeeper. Archived from the original on October 31, 2016. Retrieved November 16, 2016.
  4. Robbins, William G. "Willamette River". The Oregon Encyclopedia. Portland State University and the Oregon Historical Society. Retrieved May 19, 2014.

Works cited