Summer water releases begin from Hagg Lake

Tag : melt flow index

With the start of July, Clean Water Services will begin releasingwater from Scoggins Reservoir (Hagg Lake) into the Tualatin River.
Scientists at Clean Water Services carefully monitor the river'swater quality and flow to determine when to release water fromScoggins and Barney reservoirs. The water supplements summer riverflows and protects the environment.
Before requesting the release of water to the river, they evaluateweather forecasts, the amount of water stored in the reservoirs andthe number of remaining summer days. Their goal is to cool watertemperatures and maintain dissolved oxygen levels for fish andwildlife.
"We balance the release of enough water to cool the river now whileholding back enough for the drier months of September and October,"said Water Resources Program Manager Jan Miller. "Each day wedecide how much water the river needs by checking a network ofwater quality monitors and flow meters, and the weather reports."
The goal is to maintain an average summer flow above 150 cubic feetper second on the Tualatin River at Farmington Bridge downstreamfrom Hillsboro. The release rate will average 35 cfs - or 23million gallons a day - during July and August.
In drier September and October, the volume from Scoggins Reservoiris increased and also supplemented by releases from BarneyReservoir for an average of 70 cfs - or 45 million gallons a day.The Tualatin River needs the additional flows in the summer becauseit does not receive water from mountain snow melt.
During the late summer months, over 50 percent of the flow in thelower Tualatin River is from Clean Water Services' water releasesfrom Scoggins Reservoir, Barney Reservoir and its two wastewatertreatment facilities.
Clean Water Services was an original investor in ScogginsReservoir, built in the early 1970s to meet agricultural irrigationand drinking water needs. In the 1990s, the district joined theJoint Water Commission to expand Barney Reservoir on the upperTrask River to store additional water.
To ensure flow to the Tualatin River, Clean Water Services hasacquired nearly a quarter of the basin's stored water in the pastdecade. It works with water managers throughout the basin to secureadditional water sources for the growing industrial, municipal andenvironmental water needs through the Tualatin Basin Water SupplyProject.