All of the water that runs through Hillsboro's taps is treated surface water, which means it comes out of a river or reservoir. Hillsboro’s winter water source is the upper Tualatin River. In summer, the river level drops too low for municipal use, so Hillsboro relies upon water stored in Barney Reservoir and Hagg Lake to meet customer needs.
Hillsboro’s water is drawn out of the upper Tualatin River for filtration and treatment at either the Cherry Grove Slow Sand Filter Plant (SSF) or the Joint Water Commission (JWC) Treatment Plant. Both plants operate 24-hours per day, 365-days per year.
The SSF Plant can treat up to three-million gallons per day (MGD), providing water to Cherry Grove, the City of Gaston, the L.A. Water Co-op, Scoggins Valley, and Dilley. After treatment, SSF water flows through an 18-inch line to Dilley; along the way water is fed to Hillsboro’s rural and wholesale customers.
The JWC plant is the largest conventional water treatment plant in Oregon and is capable of treating up to 75 MGD. It provides water to the JWC partner agencies of Hillsboro, Forest Grove, City of Beaverton and Tualatin Valley Water District, and also wholesales water to North Plains. The City of Hillsboro typically uses 17.5 MGD of combined JWC and SSF plant capacities to meet customer needs, but summertime usage can push that demand up to almost 33 MGD, primarily due to outdoor watering habits.
The water is delivered to Hillsboro and beyond via two large transmission lines. There are approximately 250-miles of distribution lines in the city of Hillsboro that are fed by the transmission lines. These lines provide water to over 24,000 business and residential customers who live west of Cornelius Pass Road. The Tualatin Valley Water District serves Hillsboro residents living east of Cornelius Pass Road.
Water Service Area
A map of Hillsboro's In-Town service area and Hillsboro Western Washington County Service Area.