The Willamette Water Supply System (WWSS), a transformative infrastructure project designed to provide reliable, high-quality drinking water to 350,000 residents in Washington County, is in the final stages of construction before delivering water for Tualatin Valley Water District (TVWD) customers, including those in the Cedar Mill, Cedar Hills, and Bethany areas in 2026. The system will draw water from the Willamette River near Wilsonville, treat it at a new, state-of-the-art facility, and deliver it to residents through 30 miles of advanced, earthquake-resistant pipelines.
Our region faces shifting climate patterns, a growing population, and the ever-present threat of a Cascadia Subduction Zone earthquake. The WWSS serves as a vital solution to ensure access to safe, dependable drinking water—even in the face of uncertainties. When complete, it will be one of the most seismically resilient water systems in Oregon. It will also add a vital water supply to the region to help adapt with more flexibility to threats from a changing climate: prolonged dry years, stronger storm events, and more frequent wildfires.
The project is a partnership between TVWD and the cities of Hillsboro and Beaverton and will serve their customers and capitalize on the economies of scale with shared infrastructure.
“The Willamette Water Supply System is not just about meeting today’s water needs; it is about future-proofing our region against climate impacts and seismic risks while providing a reliable and local water supply to serve our customers,” said TVWD Commissioner Jim Duggan, who has served TVWD as a resident of Cedar Hills for more than 30 years. “This project is a monumental step in providing our community access to the clean, safe water they need, regardless of future challenges.”
This project is a $1.6B investment in the future of drinking water in our region. Construction of the new drinking water infrastructure began a decade ago and is in the final stages before completion.
Key Benefits of the Willamette Water Supply System:
High-quality Water: Water drawn from the Willamette River near Wilsonville will undergo a state-of-the-art, six-step treatment process before delivery to TVWD, Hillsboro, and Beaverton customers.Water will be tested and monitored continuously to ensure it meets or is better than state and federal drinking water regulations.
Meets Current and Future Demand: Washington County’s population is expected to grow 30% by 2050. The new system offers a dependable drinking water supply to meet current and future demand.
Adaptable to Climate Challenges: The region is experiencing increased unpredictability of weather patterns, including more heat waves, stronger storm events, and more frequent wildfires. This additional water supply helps TVWD and the cities of Hillsboro and Beaverton adapt with more flexibility to future environmental uncertainties.
Earthquake Resilient: With advanced, seismic-ready infrastructure, the WWSS is designed to remain operational during and after a major earthquake. This is vital to keeping hospitals, dialysis centers, and other critical care facilities operational.
Local Control: As a locally owned water system, the three partner public agencies have control over the management, maintenance, and cost of this water supply, maintaining local priorities and protecting residents from the uncertainties of external factors.
TVWD will begin delivering water from the WWSS to customers in 2026, taking a phased approach to delivering the new supply to our community with some customers receiving the new supply before others during the integration process.
For more information about the TVWD and Willamette Water Supply System, visit tvwd.org/wwss.