Stored water from Hagg Lake and Barney Reservoir is essential to keeping the Tualatin River cool, healthy, and flowing
The arrival of warm and dry weather and a hot forecast ahead prompted Clean Water Services to begin releasing cool water on May 31, 2023.
The Tualatin River is a vital source of water for Washington County communities, crops, and companies. To keep the Tualatin River flowing and healthy in dry months, CWS releases cool water from Hagg Lake and Barney Reservoir. Scientists closely monitor the river to determine when more water is needed to sustain water quality and the ecology of the watershed.
“With the significant spring rains, Hagg Lake is fuller than it has been in the last several years so we are starting out with a good supply of stored water to release to the Tualatin River,” said Water Resources Manager Jamie Hughes. “This a good thing given how hot the weather suddenly became in the last few weeks!”
“We are seeing stream flows drop very quickly now,” Hughes continued. “And with hotter, longer summers occurring every year, a wetter spring like the one we had this year really helps build up the water levels in Hagg Lake and Barney Reservoir that we need to maintain stream flows throughout the entire summer.”
Did You Know?
Because the Tualatin River is so small, slow, and sensitive, CWS operates under some of the most stringent water quality standards and innovative management techniques in the nation to ensure the continuous improvement and protection of the river. Learn about our first-in-the-nation approach to protecting the region’s water.
Knowing when and how much water to release is an intricate balancing act based on stream flow, irrigation and water supply withdrawals, weather, water quality conditions in the Tualatin River, and the amount of water in the reservoirs. A network of continuous monitoring data from the United States Geological Survey, Oregon Water Resources Department, and CWS helps determine when and how much water is released. CWS coordinates with the Joint Water Commission (which provides drinking water to several cities in Washington County including Hillsboro, Beaverton, and Forest Grove), the Tualatin Valley Irrigation District, the Oregon Water Resources Department, and the Lake Oswego Corporation to maintain stream flow.
In an average year, CWS releases about 30 million gallons of water per day to maintain sustainable base flows, cool temperatures, enhance water quality, and provide habitat for fish and wildlife. By late summer, more than 70 percent of the flow in the lower Tualatin River is from stored water releases from Hagg Lake and Barney Reservoir, and from CWS’ water resource recovery facilities in Forest Grove, Hillsboro, and Tigard. See the Tualatin River Flow Diagram (PDF).
CWS was one of the original investors that built Hagg Lakes’s Scoggins Dam in the early 1970s for agricultural irrigation, drinking water, and flow enhancement. With the Joint Water Commission, it expanded Barney Reservoir in 1998 to secure additional stored water. CWS has access to 24% of the stored water in the Tualatin River Watershed. The stored water is used to enhance stream flow, provide habitat, and improve water quality in the Tualatin River Watershed.
Everything we do at Clean Water Services aims to protect public health, while enhancing the natural environment of the Tualatin River Watershed. Combining science and nature, we work in partnership with others to safeguard the river’s health and vitality, ensure the economic success of our region, and protect public health for more than 600,000 people in urban Washington County. Although CWS maintains a close working relationship with Washington County government, it is separately managed and financed.
