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“Known as the Willamette Water Supply Program, the city and TVWD plan to build a joint-water system by 2026, which would draw water from the Willamette River in Wilsonville for the two water providers.”

Local officials are calling it the largest capital infrastructure project in Oregon’s history.

Priced at $1.2 billion, a new 30-mile-long water pipeline stretching from Wilsonville to Hillsboro is currently in the works, and is expected to become a new source of drinking water for more than 400,000 people in Washington County who count on Tualatin Valley Water District and the city of Hillsboro to keep their taps running.

Known as the Willamette Water Supply Program, the city and TVWD plan to build a joint-water system by 2026, which would draw water from the Willamette River in Wilsonville for the two water providers.

Much of the cost of the project is paid for by ratepayers. Water rate increases in both Hillsboro and TVWD — which provides water to about 1/3 of Hillsboro’s residents — were approved over the past few weeks.

Hillsboro gets its water from the Tualatin River and Hagg Lake, but that won’t be able to sustain Hillsboro’s expected population boom over the next several years. The city is likely to become Portland’s second largest suburb within 20 years and city planners have said they need to find additional water to meet demand.

“The Tualatin River Watershed has been, and will continue to be, a reliable drinking water source for Hillsboro,” said city water department spokeswoman Tacy Steele. “However, the addition of the mid-Willamette River as a second source will not only provide additional water needed to meet projected growth in the region, but will also bring added value to existing customers by reducing risks associated with dependency on a single source during emergency events.”

It was, in fact, emergency concerns related to the long-predicted Cascadia Subduction Zone earthquake that prompted the pipeline discussion in the first place.

In 2008, the U.S. Bureau of Reclamation released the results of its seismic assessment of Scoggins Dam at Hagg Lake. The bureau determined that a large-scale subduction zone earthquake off the Oregon Coast could cause total dam failure.

Knowing a greater supply of water would be needed as more new residents move to the county, a long-term plan to seismically improve and raise the dam was briefly considered, Steele said. But because working with the federal government — which owns the land on which the dam sits — can often take more time, funding requirements dictated the city and TVWD move sooner on seeking a solution.

A plan to dig new wells was thrown out, along with the possibility of becoming a wholesale water customer of Portland. After roughly three years of studies and community outreach, city and TVWD officials opted on partnering to create an entirely new system: the 30-mile Willamette Water Supply pipeline.

“Hillsboro currently only has one source (of water),” said Marlys Mock, spokeswoman for the Willamette Water Supply Program. “If something were to happen to the Hagg (Lake) source, you’re kind of stuck. Having the additional source is huge.”

In May, Hillsboro staff worked with city officials in Salem to negotiate the purchase of a portion of Salem’s mid-Willamette water right near Wilsonville — a deal that cost Hillsboro $16.2 million.

With the water source secured, city and TVWD staff began working with cities between Hillsboro and Wilsonville to find opportunity projects to piggyback onto for organizing construction.

The first two projects that will see actual pipeline put in the ground will occur during unrelated road work already planned at Southwest 124th Avenue in Tualatin and at Southwest Kinsman Road in Wilsonville later this year.

Other pipeline and road improvement projects in King City, Beaverton and Hillsboro are expected to follow over the next 10 years, along with construction of a new water treatment plant and storage facilities near Cooper Mountain in Beaverton.

“Owning your home or car, instead of renting, gives you more control over your property and is less expensive in the long run,” said Cousins with TVWD. “That’s really what TVWD is trying to achieve through the Willamette Water Supply Program. Ownership of our primary water source assures the district’s customers of a reliable, long-term water supply that is going to be more affordable over time.”

Read original article in the Hillsboro Tribune