The Willamette River: An Introduction

By volume, the Willamette is Oregon's largest river--and the USA's 13th largest river (outside of Alaska). About 70 percent of Oregon's population lives within 20 miles of the Willamette River.

The Willamette's flow in Portland is determined by season, upstream dams, and ocean tides--the river is tidal all the up to Willamette Falls in Oregon City. Average monthly flows range from about 8,000 cubic feet per second (cfs) in August, to over 68,000 cfs in December. Periodic winter floods can exceed 200,000 cfs. On the average about 24 million acre-feet of water flows through Portland each year in the Willamette--enough to cover the City over 250 feet deep.

The Willamette runs through the heart of Portland, supplying Oregon's largest city with an abundance of fish, wildlife, and natural areas. Native fish include Chinook, Coho, Sockeye, and Chum salmon; steelhead, rainbow, and cutthroat trout; and a variety of sculpins and minnows. Non-native fish include bass, crappie, bluegill, and catfish. Riverbanks are home to beaver, river otter, racoons, deer, coyotes, Bald Eagles, Great Blue Herons, and over 200 species of other birds.

But the Willamette has undergone a lot of change over the past 200 years. It has been dredged, channelized, diked, dammed and contaminated. The City and its partners are working to improve the health of our rivers--and there have been improvements: in 2008-09, the river's water quality was rated excellent through Portland (City of Portland Service Efforts And Accomplishments: 2008-09).

Read on to find out more about one of Oregon's defining rivers...

Willamette River Resources