Clean Water Services to begin summer water releases from
Hagg Lake/Scoggins Reservoir to restore flows in the Tualatin River

Hillsboro, OR — June 27, 2008 — On July 1, Clean Water Services will begin releasing water from Scoggins Reservoir (Hagg Lake) into the Tualatin River to maintain stream flows for water quality, fish and wildlife.

Scientists at Clean Water Services carefully monitor water quality and flow in the Tualatin River to determine when to release water from Scoggins and Barney Reservoirs to supplement summer river flows and protect the environment. Before requesting the release of water to the river, the scientists evaluate the weather forecast, the amount of water stored in the reservoirs and the number of summer days left. The goal is to cool water temperatures and maintain dissolved oxygen levels for the fish and wildlife in the river.

“We balance the release of enough water to cool the river now while holding back enough for the drier months of September and October,” said Water Resources Program Manager Jan Miller. “Each day we decide how much water the river needs by checking a network of water quality monitors and flow meters, and the weather reports.”

The goal is to maintain the average summer flow above 150 cubic feet per second (cfs) on the Tualatin River at Farmington Bridge downstream of Hillsboro. The release rate will average 35 cfs—or 23 million gallons a day—during July and August. In drier September and October, the volume from Scoggins Reservoir is increased and also supplemented by releases from Barney Reservoir for an average of 70 cfs—or 45 million gallons a day. The Tualatin River needs the additional flows in the summer because it does not receive water from mountain snow melt.

Clean Water Services was one of the original investors in Scoggins Reservoir which was built in the early 1970s to meet agricultural irrigation and drinking water needs. In the 1990s, the District joined the Joint Water Commission in expanding Barney Reservoir on the upper Trask River to secure additional stored water. In order to ensure lifegiving flow to the Tualatin River, Clean Water Services has acquired nearly a quarter of the basin’s stored water in the past decade. Today, Clean Water Services is working with water managers throughout the basin to investigate and secure additional water sources to meet growing industrial, municipal, and environmental water needs through the Tualatin Basin Water Supply Project.

During the late summer months, more than 50 percent of the flow in the lower Tualatin River is from Clean Water Services’ water releases from Scoggins Reservoir, Barney Reservoir, and its two advanced wastewater treatment facilities.

Clean Water Services is the water resources management utility for more than 500,000 people in
urban Washington County and small portions of Multnomah County, Clackamas County, Lake Oswego, and Portland. Clean Water Services operates four wastewater treatment plants, constructs and maintains flood 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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