Frequently Asked Questions

Project Need and Background

Why is the new wastewater treatment facility needed?
  • The existing Tryon Creek Wastewater Treatment Plant (TCWTP) was built in 1964 and is owned and operated by the Portland Bureau of Environmental Services (BES). It is aging and parts of the plant are at the end of their useful life cycle.
  • The facility needs significant investments to continue to reliably meet current and potentially more stringent Oregon Department of Environmental Quality (ODEQ) permit requirements and protect it against climate change.
  • Before investing in aging technologies and processes, the cities of Lake Oswego and Portland are exploring whether a new, resilient, and state-of-the-art wastewater treatment facility can be built to replace the aging TCWTP at a cost similar to or less than the costs of upgrading, modifying, and operating the existing facility.
What are the main project benefits?

A new, state-of-the-art wastewater treatment facility will produce cleaner water and ensure more environmentally sustainable services at a similar cost to upgrading the existing aging facility. Some additional benefits include:

  • Smaller footprint that enables riverfront property to be restored for future use
  • Odor control
  • More visually appealing design for the neighborhood
  • Energy efficient
  • Greater climate resiliency
  • State-of-the-art AquaNereda® water treatment technology
  • Higher quality treated water returned to the Willamette River

Public-Private Partnerships (P3)

What is the process for delivering the project?

The project is being delivered under a progressive, dual-stage approach. The first phase involves a Preliminary Services Agreement (PSA) with EPCOR Foothills Water Partners (EFWP) for design development, permitting, financial structuring, community engagement etc. The PSA phase allows the cities to make an informed decision about the costs and benefits associated with replacing TCWTP with a new, resilient, state-of-the-art facility.

At the end of the Preliminary Services period, if Lake Oswego and Portland approve moving forward with the project, the second phase will be covered under a Public-Private Partnership (P3) Agreement. The second phase will involve completing the design, construction, and commissioning of the new facility. EFWP will then operate and maintain the facility for the next 30 years according to the P3 agreement.

What is a Public-Private Partnership (P3) and how does it benefit the cities?

Public-Private Partnerships (P3) generally refer to long-term contractual arrangements between a public authority and a private partner for the design, construction, financing, operation and/or maintenance of a public infrastructure facility like the proposed Lake Oswego Wastewater Treatment Facility.

Under the P3 approach for the proposed Lake Oswego Wastewater Treatment Facility,  EFWP assumes a large share of the risks associated with designing, building, financing, operating, and maintaining the wastewater facility. This insulates the public against project risks such as cost-overruns, schedule delays, performance shortfalls, etc.

Why is a progressive dual-stage approach decision process beneficial?

The process minimizes up upfront expenditures until after the replacement wastewater treatment facility is complete. It gives the cities the opportunity to make decisions based on a definitive life cycle cost analysis and its impact on customers.

Is P3 privatization?

No.  P3 is not privatization. The new treatment facility will be 100% owned by the City of Lake Oswego and EFWP will have no title or ownership in the facility.

Has P3 been done anywhere else in Oregon?

The practice of public-private partnerships is used in Oregon for wastewater treatment.  For example, Gresham and The Dalles use private contract operators and Wilsonville is a Design-Build-Operate plant.  Lake Oswego’s use of a progressive design-build-finance-operate-maintain approach is new to Oregon.

Who is EPCOR and what is their expertise?

EPCOR has extensive experience delivering and operating wastewater treatment plants through the P3 arrangements. EPCOR USA is headquartered in Phoenix, Arizona and currently provides water, wastewater, wholesale water and natural gas services to approximately 780,000 people across 42 communities and 18 counties in Arizona, New Mexico, and Texas.

How was EPCOR Foothills Water Partners selected?

EFWP was selected through a competitive procurement process. A selection committee comprising of City of Lake Oswego and City of Portland staff reviewed the proposals and recommended the selection of EPCOR to the Lake Oswego City Council.  City Council reviewed the selection committee’s recommendation and approved a Preliminary Services Agreement (PSA) with EFWP in May 2021.

Is there an off-ramp in the process? What happens if the cities decide not to move forward with the project?

Yes. The Preliminary Services approach to this project ensures that the cities can make a fully informed decision about this project, and they are under no obligation to proceed.  If, for any reason, the cities decide not to move forward, the cities can terminate their agreement with EFWP, compensating EPFWP only for costs incurred to that date.

Affordability and Financing

How much will the new facility cost?

The costs for the new facility are not yet known.

A critical part of Preliminary Services phase is to determine the feasibility of constructing and operating a wastewater facility at similar or below the projected cost of upgrading and operating the existing Tryon Creek Wastewater Treatment Plant.

A price proposal is expected from EFWP in summer 2022 when 60% of the design has been completed. This will include a financial analysis to assess if the impacts to customer rates is the same or less than upgrading and continuing to operate the existing plant.

What is the planned rate structure?

Lake Oswego’s future sewer rates are projected to be increased by approximately 3.9% per year for 15 years. These rate projections cover the necessary Tryon Creek facility improvements and the operations and maintenance of the entire Lake Oswego wastewater system (including other capital improvements).

The new facility is expected to be built within the existing rate increase projections.

Future Ownership, Operations and Maintenance

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 (BES). TCWTP services Lake Oswego, parts of southwest Portland, and unincorporated areas of Multnomah and Clackamas counties.

When the project is complete, ownership of the new facility will be transferred to Lake Oswego. This will give Lake Oswego more control, while enabling both cities to maintain affordable wastewater treatment services.

Who will operate the new facility?

Lake Oswego will be the owner of the new facility and Portland will be a customer. The cities are partnering with EFWP under the P3 agreement to manage ongoing operations and maintenance of the facility. This P3 agreement will be in effect for 30 years.

State-of-the-Art Wastewater Treatment

What kind of technology will be used for the new treatment facility?

AquaNereda® Aerobic Granular Sludge technology was selected for the treatment facility after also evaluating Membrane BioReactor (MBR) technology. It provides tertiary treatment which will further improve wastewater quality before it is discharged to the environment.

Why was AquaNereda Aerobic Granular Sludge technology selected? What are its main benefits over MBR technology?

AquaNereda is an innovative biological wastewater treatment technology with many benefits for Lake Oswego and Portland:

  • Smaller footprint – AquaNereda technology requires less acreage enabling riverfront property to be restored for other potential uses
  • Energy efficient – Energy savings of 40%-50% compared to MBR technology
  • Environmentally friendly – Lower carbon footprint and provides high wastewater quality using less chemicals and energy
  • More efficient maintenance and operations
How does AquaNereda technology work?

Watch this brief video to learn more.

Environmental Sustainability

How will the new facility elevate the cities’ environmental commitment?

The new state‐of‐the‐art facility will have a smaller overall footprint than conventional treatment technologies and elevate the cities’ environmental commitment through

  • Energy savings (40%-50% less than MBR treatment technologies)
  • Minimizing carbon footprint
  • Discharging higher water quality to the Willamette River
How will the new facility address regulatory requirements?

The new facility will meet more stringent treatment standards than the existing TCWTP, producing effluent (liquid wastewater) that exceeds current treatment requirements for discharge to the Willamette River.

What reliability standard will the facility be designed to meet?

The new wastewater treatment facility will be designed  to meet the highest level of reliability (Class I) as required by Oregon DEQ for wastewater treatment facilities within the Willamette Valley.

How will the new facility improve resiliency?

The new facility will be constructed above the floodplain elevation and will be designed to withstand earthquakes.

Foothills Neighborhood Impact (Good Neighbor)

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

The proposed new wastewater treatment facility will be significantly more neighbor friendly. The facility will be located on a smaller 6 acre site with treatment processes housed in a fully enclosed building. 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 – treatment processes will be fully enclosed in a building
  • Reclaimed riverfront – existing property adjacent to Foothills Park will be restored for other potential future uses
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
  • Ability to restore existing TCWTP riverfront property for other potential future use
What will happen with the property where the existing facility is located?

The City of Portland currently owns the existing site for the Tryon Creek Wastewater Treatment Plant.  This site will be sold to the City of Lake Oswego for $1 under an Interim Intergovernmental Agreement (IIGA). In the future after the new facility is complete, Lake Oswego will decommission and demolish the old facility and remediate the land.

After this is complete, the property will be ready for other potential future use. Redevelopment of this property will be a separate project from the planning, design, and construction of a new wastewater treatment facility.

How will neighbors be kept up to date on the project?  Do neighbors have the opportunity to weigh in?

The City is committed to being a good neighbor and will keep residents and the general public informed and involved throughout every phase of the project. This will involve ongoing community information sessions, public meetings, a dedicated project website, ongoing project updates, and other opportunities to share information and gather feedback. To learn about upcoming opportunities, visit the ‘Get Involved‘ page.

How can I learn more?

For more information or to sign-up for e-news visit You can also contact the project team here.

Project Schedule and Permitting

What is the project schedule?
Site investigation and Preliminary Design Summer 2021 – Early Fall 2021
Design Development Fall 2021 – Summer 2022
Final Design Summer 2022 – Early Fall 2022
Permitting Summer 2021 – Fall 2022

Easements and Land Acquisition

Are easements needed and will property need to be acquired for the project to move forward?

Yes. Lake Oswego will be responsible for acquiring easements or property necessary for the project.