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Willamette River Stormwater Improvement Project

Design Phase

Region 1: Portland metro and Hood River County (Portland, Multnomah)

We are protecting fish, wildlife, water quality, and public health by building 21 stormwater treatment facilities to clean stormwater runoff from the Fremont Bridge (I-405), the St Johns Bridge (U.S. 30 BY) and U.S. 30 in NW Portland. These systems connect into our current stormwater pipes removing large debris like trash and smaller pollutants like metals and oil from the water.​


Construction Impacts

​​Impacts will be communicated when the project nears construction.

Meetings and Events

Online Open House (April 18th - May 9th):
You can access our online open house by 'clicking' the link below or by visiting our online open house platform and searching for the project.

Willamette River Stormwater Improvement Project - Open House #1 (


​​Design continues through 2025 with construction expected in 2026, but is dependent on funding and project schedule.



​We are building 21 stormwater treatment facilities to clean stormwater runoff from the Fremont Bridge (I-405), the St Johns Bridge (U.S. 30 BY) and U.S. 30 in NW Portland. These facilities include 5 underground filtration tanks next to the St Johns and Fremont bridges, and 16 modified roadside ditches and other assorted underground stormwater treatment sites along U.S 30. Each site will collect stormwater from the highways and filter it, before releasing it to the Willamette River between Sauvie Island and downtown Portland. Most sites will not be visible from roads and sidewalks because they will be underground or designed to resemble ditches.

Rain from roads and other hard surfaces pick up trash, metals such as copper and lead, oil and other petrochemical pollutants. When untreated, they wash into drains and nearby waterways diminishing water quality and habitat. Each filtration system we build will meet sustainability goals to protect our rivers, streams and groundwater, and regulations such as the Clean Water Act and Safe Drinking Water Act, by removing large debris like trash and smaller pollutants like metals and oil before they reach the Willamette River.
Above: ​​An aerial view of Portland and the Willamette River showing where the 5 bridge sites and 16 U.S. 30 sites are located. Click here to enlarge.​

What do we plan to build at each location?
St Johns Bridge (East and West)
Two underground filtration tanks: one beneath N Philadelphia Ave on the east end of the bridge with a second beneath NW Knappton-General Road on the west end.

Fremont Bridge East
An aboveground filtration tank at the base of the bridge approximately 8 feet tall and 30 feet long. Although it will be visible, the stormwater treatment system will not be visible from public parks or spaces. 

Fremont Bridge West
An underground filtration tank beneath the landscaping at the base of the bridge, near the Willamette Greenway Trail.

Fremont Bridge West Ramps
The largest underground stormwater treatment system within the project is planned beneath the parking lot at 1500 NW Raleigh Street. The site will have an approximately 12’ tall, prefabricated control room and an approximately 20’ tall tank to manage the underground system; both will be visible from the street. We are working with industry experts to determine if portions of the site could remain available for public parking after construction is finished and we will keep the public informed as the design progresses.

U.S. 30
A mixture of 16 modified roadside ditches and other underground filtration systems are planned between NW Nicolai Street and NW Marina Way. 


Multiple |

​​21 sites on U.S. 30, I-405 (Fremont Bridge), and U.S. 30B (St Johns Bridge).

Cost and Funding

​The five bridge sites are estimated to cost $12 million. The cost of the U.S. 30 sites will be available spring 2024. 


​This project will reduce water pollution to benefit water quality, fish, wildlife habitat, and public health. We are helping protect the environment by removing materials that don’t belong in our water, including fine sediment, nutrients, petroleum hydrocarbons and dissolved metals, as water runs off our highways into the Willamette River. Costs will be reduced by using our current stormwater runoff system.

Additional Information

For ADA (Americans with Disabilities Act) or Civil Rights Title VI accommodations, translation/interpretation services, or more information call 503-731-4128, TTY 800-735-2900 or Oregon Relay Service 7-1-1.

Podemos proveer la información en esta publicación en español. Para recibir la información en español, por favor llamé al (503) 731-4128.

Если вы хотите, чтобы информация об этом проекте была переведена на русский язык, пожалуйста, звоните по телефону 503-731-4128.

如果您想瞭解這個項目翻譯成 繁體中文 的相關資訊,請致電  503-731-4128.

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Contacts & Media

Project Contact

Community Affairs Coordinator
Ellen Waters

Last Updated

4/18/2024 2:26 PM

Project Number


Project Documents

Related documents to this project
22552 US 30 Corridor Mailer 12.2023.pdfA mailer with updates on six projects near U.S. 30 and U.S. 30 Byway.
Factsheet (English).pdfProject factsheet and details in English.
Fact Sheet (Español).pdfFicha informativa en español.