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.

Primary 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. 


• 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. 

Future Additional Water Source — Willamette River at Wilsonville

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.

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.  

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:

• Access the dedicated webpage


• Watch progress on YouTube


• Sign up to receive email updates

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