Frequently Asked Questions

What is the status of the process for delivering the new wastewater treatment facility? 

• In 2024, the project team evaluated competitive procurement delivery methods using public financing for implementing the next phase of the project, which involves completing the designs, constructing the facility, and operating and maintaining the facility under a long-term contract. In May 2024, City Council approved moving forward with a design-build-operate-maintain (DBOM) delivery method.
• In October 2024, the City of Lake Oswego issued a Request for Qualifications (RFQ) to shortlist qualified vendors. In August 2025, the City issued a Request for Proposals (RFP) to provide integrated design, construction, and long-term operations and maintenance services for the new wastewater treatment facility. A formal proposal is expected in spring 2026.

What are the next steps? 

• Once a proposal is received and an agreement reached, designs will be finalized and land-use permitting will resume.
• Demolition of the buildings on the new site is expected to take place in late 2026, followed by construction.

Who will own the new wastewater treatment facility?

• The current Tryon Creek Wastewater Treatment Plant (TCWTP) is owned by the City of Portland and operated by the Portland Bureau of Environmental Services.
• The current plant services Lake Oswego, parts of southwest Portland, and unincorporated areas of Multnomah and Clackamas counties.
• Lake Oswego contributes more than 50% of sewage to the plant.
• When the project is complete, Lake Oswego will own the new facility. Portland will be a major customer.

Who will operate the new facility?

As currently planned, the DBOM entity would provide long-term (20+ years) operations, maintenance, repair and replacement services for the new facility.

Schedules are subject to change. 

How is the project being financed?

• The project is being financed through a combination of a Water Infrastructure and Innovation Action (WIFIA) loan from the federal Environmental Protection Agency (EPA), municipal bonds, System Development Charges (from development), and utility revenue.

What do you expect the cost of the project will now be?

• The costs will only be known once a proposer is selected. This is expected in spring 2026.
• The project team believes that the project can still be implemented within the planned Lake Oswego rate structure of 3.9% increase per year.

What is WIFIA?

• The Water Infrastructure Finance and Innovation Act (WIFIA) program was created by Congress in 2014 to accelerate investment in water infrastructure projects like the Lake Oswego Wastewater Treatment Facility Project.
• The federal credit program helps make critical water infrastructure projects more affordable for communities and their ratepayers. It couples low interest rates with flexible, long-term repayment schedules. This lowers the cost of investment in critical water projects, extending payments over the life of the asset.
• Regionally, the Portland Water Bureau, Willamette Water Supply Program, Cascade Groundwater Alliance, and City of Beaverton have all received WIFIA loans, which will save their ratepayers millions of dollars. Other water and wastewater systems in the region are also applying for these loans to take advantage of the savings from the program.

What are the benefits of WIFIA?

• Low interest rates. The WIFIA program sets its interest rate based on the U.S. Treasury rate on the date of loan closing, the lowest possible borrowing rate in the country. This interest rate is not impacted by the borrower’s credit or loan structure, allowing borrowers to benefit from the AAA Treasure rate, regardless of the project’s credit profile.
• Customized repayment schedules. Borrowers can customize their repayments to match their anticipated revenues and expenses for the life of the loan. This flexibility provides borrowers with the time they may need to phase in rate adjustments, minimizing the impact of new projects on ratepayers.
• Long repayment period. WIFIA loans may have a length of up to 35 years after substantial completion of the project, allowing payment amounts to be smaller throughout the life of the loan, thereby minimizing the impact on user rates.

Does the City have a WIFIA loan?

Yes, on September 9, 2025, the City of Lake Oswego closed a $123 million loan from the US Environmental Protection Agency for the project through the WIFIA program.

EPA’s announcement shared: “This project will help the city modernize its wastewater infrastructure by constructing a new wastewater treatment facility to replace its existing 60-year-old plant. The new facility will be compliant with current structural code, mitigating impacts from seismic activity. Overall, this project improves the city’s wastewater services and reduces the risk of untreated wastewater spilling into the Willamette River.”

“Deferring principal payments for five years allows the City of Lake Oswego to more slowly and uniformly raise customer sewer rates, compared to a larger and more immediate rate increase of approximately 20 percent without WIFIA financing.”

Where can I get more information about the WIFIA program?

• WIFIA Program Factsheet
• WIFIA Program Benefits
• WIFIA Website

Where will the new proposed facility be located?

The proposed site for the new facility is located on the far northwest corner of the Foothills District. A map can be found here. Some of the benefits of this location include:

• Reduced flood risk
• Smaller footprint in the neighborhood

Are you still acquiring properties for the new facility?

• Yes, the plan is still to build a new facility next to the existing plant.
• Lake Oswego has been in the process of acquiring the properties and relocating the impacted businesses since 2021.
• The site serves a critical community need to supply reliable wastewater services to Lake Oswego and Portland.

Why was this location selected as the preferred site? Were other locations explored for siting the new plant?

• The site was selected because it is large enough, safer from flooding, and is close to the existing pipes and outfall to the river (thus not requiring re-routing or building new sewer mains to the plant).
• The new facility needs 6 acres of space and must be close to the existing Treatment Plant because of the utility infrastructure that is required.  As a result, the only option that meets these needs is to acquire the three properties that are next to the existing plant.

Why can’t the new plant be built on the current site?

• Consideration was given to building the new facility on the existing Tryon Creek site, however the existing plant needs to be fully operational while the new plant is being built.

What will happen with the property where the existing treatment plant is located?

• The City of Portland currently owns the existing site of the Tryon Creek Wastewater Treatment Plant, which is located within Lake Oswego.  Under the proposed new arrangement, the site will be sold to the City of Lake Oswego.  Once the new facility is complete, Lake Oswego will decommission and demolish the old facility and remediate the land.
• Planning for the future of the Foothills District is a separate project from the new wastewater treatment facility.

How will the proposed new facility benefit the surrounding Foothills neighborhood?

The proposed new wastewater treatment facility will be significantly more neighbor friendly. Benefits for the neighborhood include:

• Smaller footprint – 6-acre footprint compared to 12 acres to expand the old facility
• Better neighborhood appeal – design and landscaping will fit into the Foothills neighborhood
• Reduced odor and emissions