Each year Clean Water Services releases cool water from Hagg Lake and Barney Reservoir to enhance water quality and support fish and wildlife in the Tualatin River Watershed. Scientists closely monitor the river to determine when more water is needed to sustain water quality and stream flow. Water releases typically occur in July when stream flows drop and temperatures increase; this year releases will begin this week, nearly a month earlier.
"This is the earliest we've started water releases in more than 20 years," said Water Resources Program Manager Raj Kapur. "The only source of water in the Tualatin River Watershed is rainfall so the dry winter and spring has resulted in less water in streams and the river."
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 and other groups helps determine when and how much water is released. "We have to release enough water now to cool the river and sustain flows in the summer, but hold back enough water for the dry fall months," said Kapur.
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 enhance water quality, Clean Water Services maintains a minimum flow of 150 cubic feet per second (cfs) on the Tualatin River at Farmington Bridge downstream of Hillsboro. By late summer, up to 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.
A portion of the released water is used to restore stream flow and improve water quality in key tributaries of the Tualatin River. Clean Water Services works closely with the Tualatin Valley Irrigation District and local farmers to send water through their distribution system and release it into tributaries including McKay Creek, Dairy Creek and Gales Creek.
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 Watershed and is working with water managers to meet growing industrial, municipal, and environmental water needs.
Clean Water Services is a water resources management utility for more than 560,000 people in urban Washington County and small portions of Multnomah County, Clackamas County, Lake Oswego and Portland. Clean Water Services operates four treatment facilities, constructs and maintains drainage management and water quality projects, and manages flow in the Tualatin River to improve water quality and protect fish habitat. Although Clean Water Services maintains a close working relationship with Washington County government, it is a separately managed and financed public utility.
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Government & Public Affairs Manager
Clean Water Services