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Willamette River Stormwater Improvement Project

Welcome to our online open house, thank you for joining!

We are building stormwater treatment facilities to clean stormwater runoff from the Fremont Bridge (I-405), the St Johns Bridge (U.S. 30 Bypass) and U.S. 30 in NW Portland. The project has approximately $12 million from state and federal resources to complete preliminary design and acquire right-of-way from 2022-2024. Construction funding is being requested but this additional funding has not yet been awarded. This online open house provides a summary of the stormwater improvements and an opportunity to sign up for updates about the project. In this open house, you can learn about:

  • The stormwater improvements at the Fremont Bridge, St Johns bridge, and U.S. 30.

  • Their environmental and community benefits.

  • Anticipated traffic impacts.

  • Details about the project schedule; and

  • How you can stay connected.

Accessibility and Language Options

If you need this material in an alternative format or for ADA (Americans with Disabilities Act) or Civil Rights Title VI accommodations, translation/interpretation services, or more information call TTY 800-735-2900 or Oregon Relay Service 7-1-1.


Learn more about why stormwater should be treated before entering our waterways
Learn more about the project benefits to public health and the environment
Learn more about the 21 stormwater sites
Learn more about the future traffic impacts on U.S. 30 and parking impacts at Cathedral Park
Learn more about the project schedule and when construction is anticipated to begin
Learn how to contact us about the project or how you stay up-to-date


Rain from roads and other hard surfaces pick up trash, metals such as copper and lead, oil and other pollutants. When untreated, they wash into drains and nearby waterways diminishing water quality and habitat. Each filtration system we build will meet sustainability goals that 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.

You can see our design team assessing a site at the Fremont Bridge in the image below.

An image of our design team assessing a site at the Fremont Bridge.


The project will reduce water pollution originating from our highways to benefit Willamette River water quality, fish and wildlife habitat, and public health. These additional filtration systems will enhance our current stormwater runoff system by adding an additional filtration process at each location before the water reaches the river, which will help protect the environment by removing materials that don’t belong in our rivers, including fine sediment, nutrients, petroleum hydrocarbons and dissolved metals. 

You can see a view of the Willamette River during a rainstorm in the image below.

View of the Willamette River during a rainstorm from beneath the Fremont Bridge.

Stormwater Sites

The stormwater facilities we are building are shown in the map below. They include 5 underground filtration tanks next to the St Johns and Fremont bridges, and 16 underground stormwater treatment sites or roadside ditches along U.S 30. Each site will collect stormwater from these 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 roadside ditches.

Below, you can see an aerial view of Portland that shows where each stormwater site is located.

An aerial view of Portland showing the stormwater site locations.

Anticipated Traffic and Parking Impacts

Most sites will be constructed underground and away from streets or sidewalks to avoid temporary lane or trail impacts to the maximum extent possible. However, two areas will require temporary lane closures and parking reductions:

  • Parking at Cathedral Park (St Johns Bridge East): During construction, the parking lot beneath the east end of the bridge will be reduced to approximately 15 parking spaces to construct the stormwater treatment tank underneath the pavement. A short one-way detour around the parking area will guide visitors to available spaces from the parking lot entrance on N. Willamette Boulevard.

  • U.S. 30 in NW Portland: Intermittent lane and shoulder closures are anticipated on U.S. 30 between Sauvie Island and downtown Portland but freight access will be maintained throughout construction. Pedestrian detours will also be necessary in locations where work will occur on sidewalks, but each route will be signed and clearly marked. Some nightwork is anticipated between 6 p.m. – 7 a.m to grind the existing roadway and replace it with new concrete.  Night closures will be announced ahead of time to build awareness within the local community.

Construction is anticipated in 2026 but is pending funding and the project schedule, which are both subject to change. We are working with local neighborhood and business associations to build awareness about these temporary impacts and hear feedback about potential concerns. Additional project information on the detours, closures, and additional details about their timing will be shared at our next online open house in the winter of 2025. 

Click here to join our email list and stay up to date.


We began the environmental and land use permitting process in October 2023 shortly after starting the project. The preliminary design phase was recently completed. This is the first of two anticipated online open houses to update you about the project: this open house focuses on introducing the project while the second open house will focus on the anticipated construction schedule and traffic impacts. Construction is anticipated in 2026 pending funding and the project schedule, both of which are subject to change.

February 2023l Design phase began. 
October 2023 l National Environmental Policy Act (NEPA) and land use permitting process began.
April 2024l Preliminary design complete.
April 2024l First public online open house.
Winter 2025l Design anticipated to be complete.
Winter 2025l NEPA and land use permitting process anticipated to be complete. 
Winter 2025l Second public online open house anticipated to begin.
Spring 2026l Earliest construction could begin depending on when funding is awarded. 

How to Stay Informed

We will host a second online open house in 2025 to provide additional details about construction, anticipated traffic impacts, and how to stay informed throughout construction. 

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