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Willamette River Watershed

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Photo shows several small sailboats sailing on the Willamette River.
The Willamette River Basin is the largest watershed in the state, covering more than 11,500 square miles. The Willamette River flows through the heart of downtown Portland and is a vital connection for fish and wildlife migrating to habitat and spawning streams.

About the Willamette River Watershed

The Willamette River is formed by the confluence of the Middle and Coast Forks that originate in the mountains south and southeast of Eugene. The river flows almost 200 miles to the Columbia River in North Portland and drains more than 7 million acres of land.

Portland sits at the end of the drainage basin and is the most urbanized part of the watershed. The city occupies only a small fraction of the river's watershed, but the 20 miles of Willamette River that pass through the city are a critical gateway for many of the region’s fish and wildlife. Young salmon and steelhead live in the lower Willamette and its tributaries year-round, from between a few months to a couple of years depending on the species’ life cycle.

During the life cycle of salmon and steelhead, they migrate through Portland twice – once as juveniles on their way to the ocean and again as adults on their way back to spawn. The Willamette River is the only connection these fish have to their spawning grounds – places like Johnson or Crystal Springs creeks – where they can build nests, lay eggs, and mate.

Portland Harbor

The final stretch of the river near its confluence with the Columbia River is one of the largest and most complex Superfund sites in the country. Because of its key location on the Willamette, Portland Harbor has a long history of shipping, industrial, and commercial activity. This area of the river from the Broadway Bridge to Sauvie Island also has historical, natural, and cultural resource significance.

After two decades of study and investigation, the Portland Harbor Cleanup moved into a new phase of the clean-up process. Find information about the cleanup from the U.S. Environmental Protection Agency and the Oregon Department of Environmental Quality.

Portland’s Report Cards

All of the Portland metro region is within the Willamette River watershed. However, the area that we study and include in our report cards is defined as the parts of the city that do not drain first into a subwatershed like Johnson Creek, the Columbia Slough, or Tryon Creek and includes land east and west of the river.

Portland’s Willamette watershed includes:

  • The mainstem of the river and and everything that drains to it.
  • Miles of tributary streams in the West Hills and Forest Park. Stephens Creek, Balch Creek, and Tanner Creek are examples of these tributaries.
  • Downtown Portland and some of Portland’s oldest and most dense residential neigh-borhoods. Here, the historic streams were long ago filled in or piped and paved over for development.

How the Watershed Is Doing Today 

The most recent report cards show we have work to do to improve watershed health. The 2023 Watershed Health Index data resulted the following grades for the Willamette River Mainstem: 

  • Hydrology – C
  • Water Quality – B
  • Habitat – D+
  • Fish and Wildlife – We are still developing scoring criteria for this category.

Grades for the Willamette Tributaries were not much better:  

  • Hydrology – C-
  • Water Quality – B-
  • Habitat – B+
  • Fish and Wildlife – C-

Review the Willamette River Mainstem watershed report card.

Review the Willamette River Tributaries watershed report card.

Review the 2015 Eco Health Report Card for the entire Willamette River — a project of the Meyer Memorial Trust and University of Maryland Center for Environmental Science. 

Work We've Done to Improve Conditions

Environmental Services has worked with many partners to monitor and improve the health of the Willamette River watershed. That work includes to:

Prevent Combined Sewer Overflows

 In 2011, Environmental Services completed the Big Pipe Project, which has reduced combined sewer overflows or CSOs to the Willamette River by 94 percent. Construction is done, but our work continues as we operate and maintain the system to protect the river, especially during Portland’s rainy winters. Read more about Portland’s Big Pipe and track its progress during rainstorms.

Protect Cold Water Tributaries

The Willamette River is often too warm to adequately support native fish, so they depend on cold water flowing into the river from its many tributaries. As a result, we must protect the tributary streams that flow into the Willamette like those flowing through the River View Natural Area. Once part of the cemetery, this large, undeveloped, and densely forested land delivers cool water from seven streams into the Willamette at spots that salmon and steelhead like to hangout. Environmental Services, Metro, and the Trust for Public Lands bought the land for the natural area, which is also home to more than 130 species of plants, 31 species of mammals, and 74 species of birds.  

Increase Shallow Water and Off-channel Habitat

Juvenile salmon hug the shoreline as they head out to the ocean. They seek refuge — or places to find food, rest, and safety from predators — in the shallow waters and areas out of the fast-flowing main channel. Projects like the Stephens Creek Confluence and Oaks Bottom Habitat Enhancement projects have restored those spaces for salmon by removing obstacles and increasing the complexity of the habitat. Read more about watershed restoration work.

Find more information about previous restoration projects on our restoration and monitoring map.

Work We're Doing to Improve Conditions

Environmental Services and our partners continue to expand and build on past efforts. We continue to work to:

Manage Stormwater and Add Green Infrastructure

Several of our sewer and stormwater improvements within the watershed add green infrastructure like green streets, which help keep rain out of pipes. This is especially important in the combined sewer area where rain and sewage flow through the same pipes to the treatment plant. In the Buckman-Kerns Green Street and Sewer Project alone, Environmental Services plans to construct more than 70 green street planters to help keep the runoff from more than 15,000 square feet of streets and sidewalks out of the neighborhoods’ sewer pipes. Learn more about green streets or how we manage stormwater.

In addition, Environmental Services works with private property owners to add green solutions on their land to reduce rainwater going into pipes. Learn more about how you can manage the rain on your property.

Make Connections

Salmon migrate to the ocean. Birds head south in the winter. Fish and animals need to migrate throughout their lives to find food and shelter. When we plant trees, enhance wetlands, remove culverts, and restore floodplains, we create connections or corridors for fish and wildlife who use them to move around like we use our streets. Projects like the Miller Creek Culvert and Restoration Project will remove obstacles to help reconnect fish with habitat.

Restore Tributaries

Remember, all of Portland’s streams flow to the Willamette River. Environmental Services’ sewer, stormwater, and watershed restoration projects in the tributaries protect and improve conditions in the Willamette. For example, several projects are planned in the Stephens Creek watershed to slow stormwater flows, treat runoff to protect water quality, improve habitat, add trees and plants and reduce flooding risks.

Find information on all our current projects that are working to protect and improve watershed health.

Important Fish and Wildlife 

The Willamette River is critical habitat for salmon, steelhead, lamprey, and other fish listed on the Endangered Species Act. Learn more about salmon in Portland's rivers and streams.

Lower Willamette Mainstem

More than 30 percent of the fish captured in the Lower Willamette are non-native. Native largescale sucker and chinook salmon are the two most commonly captured fish. Smallmouth bass and common carp are the most commonly captured non-native species.

Osprey and bald eagles are the two most common seen raptors along the river. In fact, eagles routinely steal fish that osprey have worked hard to catch. Peregrine falcons nest on many of the river’s bridges and spend their days hunting small and medium-sized birds high over the city. In fall and winter, a variety of gulls frequent the river as do double-crested cormorants. Resident Canada geese are the most commonly seen bird along much of the river front. They are sometimes joined by larger flocks of migratory cackling geese from Alaska and Canada.

Willamette Streams

The lower Willamette tributary streams have the largest cutthroat trout populations in the city,  particularly in Balch, Tryon, and Miller creeks. Culverts in the streams block fish from accessing often the highest quality habitat in the city. Johnson Creek in SE Portland supports coho salmon production (both spawning and rearing), and is one of the most important salmon and steelhead rearing streams in the city. Many of the city’s tributary streams are fishless or have very low numbers of fish, and although Balch Creek has the largest cutthroat population in Portland, no other fish species have yet been detected in that large, high-quality stream.

Downstream of the culverts, the Willamette streams are some of the most species-rich reaches in the city where they join with the mainstem. The Stephens Creek confluence is the only stream reach in the city where the four most common salmon or trout species have been captured (chinook, coho, cutthroat and rainbow/steelhead trout). The mouth of Miller Creek is the only other site where three of those salmonids have been captured. Chinook have not yet been detected there.

Extensive tree canopy along the Willamette streams supports many common native bird species. Robins, spotted towhees, and juncos are common in neighborhoods. Deeper forest habitats are where you will find Swainson’s and varied thrushes, brown creepers, and Pacific-slope flycatchers. Wilson’s warblers sing scratchy songs from low brush in the forest while black-throated gray warblers sing fast buzzy songs from the canopy of maples and alders. In the last two decades, a few pairs of ravens have moved into Forest Park. Listen for their deep, croaky calls.  Sharp-eyed observers may also spot a hairy woodpecker, the larger relative of the more common downy woodpecker.

How to Experience the Willamette River

There are countless ways to enjoy the Willamette River watershed, from strolling along the river downtown, to viewing its confluence with the Columbia at Kelly Point Park, to paddleboarding, kayaking, and more.

Check the Rec: Willamette River Water Quality Testing

Environmental Services checks temperature and tests water quality year-round along the Willamette’s mainstem. During the summer months, we increase that to weekly and add several popular recreation areas on the river. Learn more about Check the Rec and get weekly updates during the summer.

Fishing on the Willamette

Sport fishing is a great way to enjoy the river. Find more information about where fishing is permitted in city parks. Fishing is not permitted on any tributary streams.

Fish Advisories

Multnomah County and the Oregon Health Authority post advisories about which fish to eat and which fish to avoid. Find the health authority's Lower Willamette Fish Advisory and all fish advisories and guidelines. Find Multnomah County's fish advisories.

How to Get Involved 

Several organizations host stewardship opportunities in the Willamette River watershed. A few include: