For 150 years, Hillsboro and its partners across the Tualatin Basin have collaborated to ensure water availability for municipal, agricultural, environmental, and recreational needs.

Water service began with the Peoples Water and Gas Company, which delivered water from Sain Creek in western Washington County through a wooden pipe. The original Utilities Commission later built a Tualatin River intake at Haines Falls, running an 18" steel line 26 miles to Hillsboro. That line still serves upper-system customers today, though the north transmission line was built in the late 1990s to serve in-town customers.

In the 1960s, Hillsboro began work to expand its infrastructure to capture winter water for summer use. Barney Reservoir uses a gravity-fed transfer system to move stored water to the Tualatin River intake, while Scoggins Reservoir releases water in summer to protect streamflow, fish, and water quality.

Hillsboro has a strong tradition of long-term planning — looking 50+ years ahead to ensure future generations have access to clean, reliable drinking water. As the largest city in Washington County, Hillsboro today serves a diverse base of industrial, commercial, and residential customers.

Historical Highlights

1913

Public water service begins with the Sain Creek connection to Hillsboro via wooden pipe. 

1940

The City of Hillsboro purchases the water system and forms the Utilities Commission. 

1970 - 1974

The original Trask Dam is completed, and Barney Reservoir is formed. Scoggins Reservoir was completed, forming Hagg Lake.

1976

The Joint Water Commission Water Treatment Plant was completed, with an original capacity of 20 million gallons per day (MGD). After multiple expansions, the current capacity is 85 MGD. 

2013 - 2026

The Willamette River was selected as Hillsboro’s preferred additional water source. The Willamette Water Supply Program designed and constructed a new water supply system, including a new water intake facility, water treatment plant, transmission lines, and reservoirs. The Willamette Water Supply System will be Hillsboro’s additional water source to increase reliability, provide redundancy, and improve seismic resiliency.