Tap Into Tomorrow: Willamette Water Supply System

The Willamette Water Supply System (WWSS) has been in the works for over a decade to help our community face future water challenges and build seismic resiliency.

The new water source from the Willamette River will be treated at a state-of-the-art water treatment plant before coming to Hillsboro customers. This will supplement our current water supply, creating a more reliable system for generations to come.

Staff are hard at work getting Hillsboro's distribution system ready to bring in a new supply this year. Minor changes could occur during the integration process, like a difference in taste or smell, but changes will be temporary and will not pose a health risk.

Thanks to our water treatment processes and rigorous water quality testing, most customers will not notice a difference in their water service. But behind the scenes, Hillsboro will be better prepared than ever-with two water sources ensuring reliable, high-quality water for our community, even in emergencies.

Timeline

2012 - 2013 Long-term Water Supply Study

The City of Hillsboro conducted a Long-term Water Supply Study to select a future water supply capable of meeting forecasted demands for the next 50 years. Community members were invited to provide feedback that became the evaluation criteria for each source. Five potential water sources were considered and judged based on criteria like cost, source water quality, reliability, redundancy, risk, and others.

2014 - 2016 Water Supply Selection & Preliminary Planning

Hillsboro and the Tualatin Valley Water District selected the Willamette River as the preferred water supply. Both agencies completed multi-year technical studies and collected public input to evaluate potential sources The Willamette River was selected based on lower cost to reduce impacts on water rates, excellent water quality, increased system reliability, and fewer environmental impacts.

2016 - 2025 Design, Permitting, and Construction

The Willamette Water Supply Program managed the infrastructure construction needed for a new water supply system. Over 30 miles of pipeline was installed to transmit water from Wilsonville, through Beaverton, to Hillsboro. Pipeline construction was paired with other utility projects where possible to minimize disruptions and save money.

2018 Integration Planning

Integration planning facilitates the transition and ensures water will remain safe to use and drink when the new system comes online. Preparations included researching other water supply integration projects, conducting lab and field studies, modeling the blend of two supplies, increasing water quality monitoring, and preparing the distribution system through flushing.

2022 Water Treatment Plant Construction

Construction began on a new state-of-the-art water treatment plant. Water will be treated using the latest technology to meet or exceed strict drinking water standards. The plant will initially produce up to 60 million gallons of water per day (MGD) but will be designed for a maximum of 120 MGD.

2023 - 2024 Cornelius Pass Road & Orenco Woods Nature Park Pipeline Construction

The Cornelius Pass Road Pipeline Project was a 3.3-mile section of pipeline between Frances Street and the Tualatin Valley Water District connection point just south of Highway 26. About 900 feet of this section of the pipeline crosses the northeast corner of Orenco Woods Nature Park (OWNP).

Trail improvements were completed in tandem with this project, increasing public access during high-water events and protecting habitat for fish and wildlife.

2026 WWSS Commissioning & Startup

Once the construction on the new water treatment plant is complete, it will undergo multiple tests to ensure water quality standards are met before water is delivered to Hillsboro.