Hillsboro, OR — June 28, 2006 —
On July 1, Clean Water Services will begin releasing water from Scoggins Reservoir (Hagg Lake) to the Tualatin River to improve water quality and protect fish and wildlife by maintaining stream flows.
During the dry summer months, scientists at Clean Water Services carefully monitor the water quality and flow of the Tualatin River to determine when to release stored water from Scoggins and Barney Reservoirs to restore river flows and protect the environment. The scientists must consider the weather forecast, the amount of stored water available in the reservoirs and the number of summer days left before requesting the release of water to the river. The goal is to augment flows to cool water temperatures and maintain dissolved oxygen levels that protect the fish and wildlife in the river.
“It’s a delicate balancing act,” says Water Supply Project Manager Tom VanderPlaat. “We need to release water now to cool the river, but we also have to hold back enough water to release during the drier months of September and October. I’m one of the few people in town who cheers for summer rainstorms.”
Clean Water Services uses a cadre of water quality monitors, flow meters and weather data to make daily decisions on reservoir releases. The District’s goal is to maintain the average summer Tualatin River flow above 150 cubic feet per second (cfs) at Farmington Bridge downstream of Hillsboro.
In July and August, the release rate will average 35 cfs—or 23 million gallons a day. During the drier months of September and Octobers, releases from Scoggins Reservoir will increase and releases from Barney Reservoir will start resulting in an average of 70 cfs—or 45 million gallons a day. The water released from the reservoirs supplements the river flows in the summer because the Tualatin River does not receive water from mountain snow melt.
Clean Water Services was one of the original investors in Scoggins Reservoir when it 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 the last decade, Clean Water Services has acquired nearly a quarter of the basin’s stored water to restore life-giving flow to the Tualatin River during the dry summer months. Today, Clean Water Services is working with water managers throughout the basin to investigate and secure additional water sources to meet the growing industrial, municipal, and environmental water needs.
During the late summer months, Clean Water Services’ water releases from Scoggins Reservoir, Barney Reservoir, and its two advanced wastewater treatment facilities account for more 50 percent of the flow in the lower Tualatin River.
Clean Water Services is the sanitary sewer and surface water management utility for more than 480,000 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.