Drinking Water Sources

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The City of Hillsboro Water Department proudly serves high-quality drinking water to more than 93,000 customers. Every drop of water that runs through customers’ taps comes out of a river, or a dam and reservoir.

Current Water Source - Upper Tualatin River

Winter Source
Hillsboro’s winter drinking water source is the upper-Tualatin River and its tributaries. The river stretches almost 80 miles from the Tillamook State Forest in Washington County to the Willamette River near West Linn. The Tualatin River has been Hillsboro’s only winter drinking water source for almost 80 years.

Summer Sources
In the summer, the river level drops too low for community use, so Hillsboro customers rely upon water stored in two reservoirs to meet demand:

The Barney Reservoir is located in the Trask River Watershed and holds 20,000 acre-feet of water at capacity, of which 14,886 acre-feet is available for drinking water. (An acre-foot is the amount that covers an acre with a foot of water and is equal to 325,851 gallons.) Water is moved from the reservoir to the Tualatin River through a one-mile-long pipeline.
- Learn more and access water level and flow rate information.
The Scoggins Reservoir — also known as Hagg Lake — is located near Gaston. The reservoir stores approximately 53,323 acre-feet of water when full, of which 13,500-acre feet is available for drinking water. Learn more and access water level and flow rate information.

Take a virtual tour of the Tualatin River Watershed.

Future Additional Water Source - Willamette River at Wilsonville
While the upper-Tualatin River will continue to be Hillsboro’s primary water source, the City of Hillsboro is partnering with the Tualatin Valley Water District and the City of Beaverton to develop the Willamette River at Wilsonville as an additional water supply source by 2026.

Design and construction of the new Willamette Water Supply System (WWSS) is underway, and includes building:

A modified water intake on the Willamette River at Wilsonville
A state-of-the-art water treatment plant in Sherwood
Water supply tanks (reservoirs) in Beaverton
More than 30 miles of large-diameter transmission water pipeline traveling from Wilsonville to Hillsboro

The entire WWSS will be built to modern seismic standards and designed to withstand the impacts of a large earthquake or other natural disaster. This will help restore service quickly after a catastrophic event.

WWSS related projects in Hillsboro include:

Cornelius Pass Road Pipeline Project, including pipeline installation in the northeast corner of Orenco Woods Nature Park
South Hillsboro Pipeline Project

The total investment for the WWSS is currently estimated at $1.6 billion dollars, split between the three partners with the City of Hillsboro investing about 36%.

Learn More about Hillsboro's Future Additional Water Supply Source

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