Drinking Water Supply
Beaverton's Drinking Water Sources
The primary source of filtered drinking water in Beaverton’s service area is the Joint Water Commission (JWC) Water Treatment Plant located south of Forest Grove. The water treatment plant filters surface water pumped from the nearby upper Tualatin River. The water treatment plant can produce up to 75 million gallons a day (mgd) of finished drinking water. The City owns a 25% share in the water treatment plant, allowing the City up to 18.75 mgd of treated water.
About the JWC
The City is a member of the JWC, which is an intergovernmental water supply group whose owner-members include the cities of Beaverton, Hillsboro, Forest Grove, and the Tualatin Valley Water District. The JWC was established to store, manage, treat, and convey drinking water for the owner-member agencies, and it supplies water to as many as 400,000 people.
Beaverton's Water Rights
During the summer, when drinking water demand is high and Tualatin River streamflow is low, water is released from Hagg Lake (Scoggins Reservoir) and Barney Reservoir (formed behind a dam on the Trask River in the Coast Range). The water spilled from the two dams is to compensate for the amount removed from the Tualatin River for Beaverton’s summer use. Water released from Barney Reservoir is diverted by pipes from the Trask River basin into the upper Tualatin River.
The City of Beaverton owns yearly water rights of up to 1.3 billion gallons (4,000 acre-feet) in Scoggins Reservoir and 1.4 billion gallons (4,300 acre-feet) in Barney Reservoir. Water originating from Scoggins Reservoir and Barney Reservoir is the source of most of the City’s raw water (before treatment) during the summer. Release of stored raw water from the two dams increases summertime streamflow in the Tualatin River, helping to sustain a healthy river ecosystem. Every winter and spring, the City uses its 16 mgd natural streamflow water right to meet daily water supply demands. Surface water from the Tualatin River is filtered in the JWC Water Treatment Plant before delivery to the City of Beaverton.
Finished drinking water from in the JWC Water Treatment Plant is pumped about one-half mile up to the Fern Hill Reservoirs, two 20-million-gallon, above-ground storage reservoirs situated at 520 feet elevation. To transport water from the water treatment plant to Beaverton, the City owns 14 million gallons per day (mgd) capacity in the JWC South Transmission Line.
The City also owns emergency backup capacity in the parallel JWC North Transmission Line. From the two Fern Hill Reservoirs, water travels about 20 miles by gravity through large-diameter transmission lines to Beaverton, where the City’s two terminal water storage reservoirs are located in central Beaverton. The City’s two terminal water storage reservoirs hold a combined total of 20 million gallons.
Aquifer Storage & Recovery (ASR)
Since 1999, the City has used aquifer storage and recovery (ASR) to temporarily limit the purchase of new water supply facilities. During the winter and spring, Beaverton injects treated drinking water from the JWC Water Treatment Plant into natural underground basalt formations (aquifers), displacing native groundwater. During the summer months, treated water is recovered from ASR wells to supplement JWC surface water to help meet peak season demands (up to 17 mgd).
Acting as a conservation measure, ASR conserves surface water from primary sources (rivers and dams) during environmentally stressful summer seasons. Beaverton has reduced its diversion of limited summer river streamflow and water stored behind dams by substituting stored water recovered from ASR wells.