Scoggins Dam at Hagg Lake
The upper Tualatin River would be a mere trickle in the dry months, if not for Clean Water Services' life-giving releases of cool water from Hagg Lake and Barney Reservoir. Because the Tualatin River is a vital source of water for Washington County's abundant agricultural crops and growing population, scientists closely monitor the river to determine when more water is needed to sustain water quality, fish and wildlife.
Dry, warm weather has prompted Clean Water Services to begin releasing cool water this week, following the trend in the last few years of releasing water earlier than normal. The annual releases typically occur in July when stream flows drop and temperatures increase.
"This is the third year in a row we've started water releases earlier than normal," said Water Resources Analyst Jamie Hughes. "We have to release enough water now to cool the river and sustain flows in the summer and through the dry fall months," said Hughes.
Knowing when and how much water to release is an intricate balancing act based on stream flow, weather, water quality conditions in the Tualatin River, and the amount of water in the reservoirs. A network of continuous monitoring data from United States Geological Survey, Oregon Water Resources Department, Clean Water Services and other groups helps determine when and how much water is released.
In an average year, Clean Water Services releases about 25 million gallons of water per day in July and August, and about 35 million gallons per day in September and October to cool temperatures, enhance water quality, and provide habitat for fish and wildlife. In order to improve water quality, Clean Water Services maintains a flow of 165 cubic feet per second (cfs) in the Tualatin River at Farmington Bridge downstream of Hillsboro. By late summer, more than 70 percent of the flow in the lower Tualatin River is from Clean Water Services' water releases from Scoggins and Barney Reservoirs, and its two advanced treatment facilities in Hillsboro and Tigard. See the Tualtin River Flow Diagram (PDF, 585KB).
Clean Water Services also began releasing water from the Forest Grove treatment facility and Natural Treatment System (NTS) earlier this month. The NTS creates an ecological bridge between treatment and the watershed, where thousands of native plants cool and naturalize the water before it's returned to the river. With the release of water from Forest Grove, Clean Water Services is also working to maintain stream flow in the upper Tualatin River, which has significant withdrawals for drinking water and irrigation. Clean Water Services coordinates with the Joint Water Commission (which provides drinking water to a several cities in Washington County including Hillsboro, Beaverton, and Forest Grove), Tualatin Valley Irrigation District, and the Oregon Water Resources Department to maintain stream flow.
Clean Water Services was one of the original investors that built Scoggins Dam in the early 1970s for agricultural irrigation, drinking water, and flow augmentation. With the Joint Water Commission, it expanded Barney Reservoir in 1998 to secure additional stored water. Clean Water Services now controls nearly a quarter of the stored water in the Tualatin River Watershed and is working with water managers to meet growing industrial, municipal, and environmental water needs.
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 570,000 residents and businesses in urban Washington County.
Government & Public Affairs Manager
Clean Water Services