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.
  • Lake Oswego, with Portland’s support, has been using a phased approach that could replace the aging Tryon Creek plant, with an environmentally sustainable wastewater treatment facility, at a good value to the community.

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 water treatment technology
  • Higher quality treated water returned to the Willamette River

Project Status

What is the status of the process for delivering the new wastewater treatment facility? 
  • Lake Oswego, with Portland’s support, has been using a phased project approach to replace the aging Tryon Creek plant with an environmentally sustainable wastewater treatment facility, at a good value to the community.
  • The first phase of the project is now complete, which included developing facility designs, preliminary permitting, and proposed pricing for the Wastewater Treatment Facility Project.
  • On Tuesday, January 30, 2024, the Lake Oswego City Council voted to not proceed with a 30-year project agreement with EPCOR to design, build, finance, operate, and maintain (DBFOM) a new wastewater treatment facility. Instead, Lake Oswego will explore a competitive procurement method using public financing, to complete the design, construct the facility, and operate and maintain the facility under a long-term contract.
What did the first phase achieve?
  • The first phase successfully demonstrated the feasibility of building a new plant away from the riverfront. It also enabled the cities to make a fully-informed decision about the costs and benefits associated with the private-public partnership approach to constructing the project.
Why would Lake Oswego change the project delivery approach now and not move forward with EPCOR?
  • The progressive phased approach was intentionally designed to allow Lake Oswego to determine whether it would be getting the best possible value for ratepayers and customers from a DBFOM private-public partnership with EPCOR, or if there is value in engaging other entities through a competitive method, with public financing.
  • There was never a guarantee or commitment for Lake Oswego to proceed with EPCOR to phase 2, under the public-private partnership model.
  • The proposed cost of the private financing provided by EPCOR poses significant cost burdens on ratepayers and customers, compared to public financing. Therefore, it is not financially beneficial to enter phase 2 with EPCOR.
  • The cities believe it would be more cost-effective and a long-term benefit for ratepayers for the next phase of the project to take place using 100% public financing, as opposed to the public-private partnership DBFOM approach.
What accomplishments and products resulting from phase 1 can be applied to the new competitive method for phase 2?
  • Depending on the technical approaches proposed under the competitive method, the facility design, residuals study, environmental studies, geotechnical reports, commissioning/testing plans, startup and transition plans, archaeological investigations, and operational plans will likely be able to be applied.
  • In addition, phase 1 yielded products that will be necessary or useful moving forward, including:
    • Detailed cost estimates and financial structuring to assess affordability and potential implications on rates and charges.
    • Earmarked approval for a Water Infrastructure Finance and Innovation Act (WIFIA) loan.
    • Preliminary draft of Oregon Department of Environmental Quality (DEQ) discharge permit.
    • An Intergovernmental Agreement (IGA) between Portland and Lake Oswego to initiate the project, and a framework for an IGA to address future services to Portland.
    • Public engagement and input into the design of the facility.
    • Progress in acquiring the three properties that are adjacent to the existing Tryon Creek Wastewater Plant to be the location of the new facility. This included relocating 16 of 18 businesses.
    • Proof that a new facility can be built within the proposed footprint of 6 acres.
    • Detailed understanding of each city’s requirements related to the Wastewater Treatment Facility Project.

Next Steps and Schedule

Is the project still moving forward? Will you go back to upgrading the old plant, instead of replacing Tryon with a new facility?
  • Yes, the project is still moving forward.
  • There are currently no plans to upgrade the existing Tryon Creek plant, as it has reached the end of its useful life.
  • The cities are committed to replacing the current plant.
  • They still believe it is the best financial decision to build a new, cost-effective, resilient, state-of-the-art facility capable of meeting increasingly stringent regulatory requirements, rather than investing in the outdated plant.
What will the project delivery method for the next phase be, if you aren’t going ahead with EPCOR?
  • In 2024, Lake Oswego plans to explore a competitive procurement method with public financing to complete the design, construct the facility, and operate and maintain the project under a long-term contract. This is known as a design-build-operate-maintain (DBOM) delivery method.
  • The next step will involve gauging interest and soliciting input from DBOM firms/teams and industry experts, determining market interest for the DBOM approach, especially in light of the current level of design plans for the facility.
  • Once market interest has been established, the city would issue a request for proposals (RFP) from qualified firms.
  • The cities believe that a competitive procurement method will provide better long-term value to both communities.
What does this mean for the timeline?
  • It will extend the procurement timeline by about a year, potentially longer.
  • Schedules will be further developed once a firm is hired for the next phase.
  • The City will work as practically as possible to reduce delays.
Will you need to redesign the new facility?
  • It is likely there will be some adjustments to the current design, depending on the DBOM entity’s proposed design, construction, and operations approach.
  • We will continue to use the valuable input from residents and stakeholders to finalize the design.
Will AquaNereda technology still be used for the treatment process?
  • The AquaNereda treatment technology is preferred by the cities based on our phase 1 work, due to the site constraints and the environmental sustainability benefits it provides. This preference will be communicated to DBOM entities during the procurement method.
  • However, opportunities will be provided to proposers to offer alternative treatment technologies, as long as they meet the original project goals. 
Who will own the new wastewater treatment facility?
  • A change from a DBFOM delivery method with EPCOR to a DBOM delivery method, with public financing, does not affect the ownership of the new 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.


How was the project originally to be financed? Why does the City believe it can get a lower price than that offered by EPCOR?
  • The project was originally scoped to be privately financed, through a combination of a WIFIA loan (for 49% of the project), private debt, and at-risk equity provided by EPCOR.
  • By using lower cost public financing, the City believes that it can significantly reduce the cost burden of the project on ratepayers and the public.
What is the impact of the project qualifying for the federal EPA WIFIA loan during the phase 1 work?
  • The project was selected to apply for a WIFIA loan in December 2021.
  • The low-cost WIFIA loan significantly improves the affordability of the project.
What do you expect the cost of the project will now be?
  • The costs will only be known once the procurement method is finalized and a DBOM proposer is selected.
  • The project team believes that the project can still be implemented within the planned Lake Oswego rate structure of 3.9% increase per year.

Property Acquisition

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 in close proximity 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.