South Hillsboro Pipeline Project

PLW_1.1 2017-06-12

Development of South Hillsboro, a 1,400-acre mixed-use community, requires coordination between multiple agencies and infrastructure projects. The Willamette Water Supply Program is coordinating with the City of Hillsboro, Washington County, and private developers to install the portion of the Willamette Water Supply pipeline that will serve the City of Hillsboro. To date, approximately 4,100 linear feet of the Willamette Water Supply pipeline has been installed in coordination with South Hillsboro road projects.

Pipeline construction began in the summer of 2020 on the southern section of the South Hillsboro Pipeline (PLW 1.3). The section of the pipeline under construction is approximately 10,700 feet in length, connecting on the north to the pipe that has already been installed through South Hillsboro. The PLW_1.3 pipeline alignment follows the future Cornelius Pass Road alignment south to Rosedale Road and then east along Rosedale Road to 209th Avenue. The pipeline will connect to the Tualatin Valley Water District system at the intersection of SW Farmington Road and 209 th Avenue. Construction of this segment is anticipated to be complete in 2022.

Construction of the final section of the South Hillsboro pipeline project – an approximately 3,800 linear foot segment between the Cornelius Pass Road and TV Highway intersection and Frances Street – is scheduled to begin in 2022. This segment of the pipeline is being constructed in partnership with Washington County’s Cornelius Pass Road widening project.

The coordinated construction of the pipeline and the Cornelius Pass Road improvements and extension saves money, reduces community and neighborhood impacts, and minimizes the need for multiple construction projects.


Construction Updates


Thank you for your patience during the recent road closures. Crews will continue work on Rosedale and 209th in the upcoming months. There may be lane closures and flaggers controlling traffic.


The microtunnel boring beneath Butternut Creek is underway. The work is noisy at times. The pipe will be installed in the tunnel this summer.


Approximately 3,800 linear feet of 30-inch pipe has been installed along SW Rosedale Road and SW 209th Avenue. The next segment of pipe to be installed is the 66-inch pipe through South Hillsboro.

Our Reliable Water

Program Timeline

Developing the new Willamette water source will take over a decade.

Willamette Water Supply Program

Willamette Water Supply Program