The U.S. Army Corps of Engineers plans to draw down the reservoir feeding west central Oregon’s South Santiam River earlier than the normal pace as a test to see how they might better operate Foster Dam to improve the survival of spring chinook, winter steelhead and other fish.
The South Santiam River, a tributary of the Santiam River, is about 66 miles long. The Santiam, drains an area of the Cascade Mountains and flows into the Willamette River near Corvallis. The Willamette flows north to join the Columbia River at Portland.
The Corps this week issued an alert to boaters, fishers and others on the South Santiam River near Sweet Home, Ore., that Foster Reservoir water levels will drop more rapidly than usual in October as the Corps draws the reservoir down to its winter flood control elevation.
The Corps normally draws Foster Reservoir down from its summer elevation of 637 feet above sea level to its winter elevation of 613 feet between Oct. 1 and Nov. 15. This year, the Corps intends to draw down the reservoir to 616 feet by about Oct. 15.
For many years the Corps has held the reservoir’s water level between 613 and 616 feet in April and May, allowing the surface water where juvenile steelhead usually swim to gently spill through a notched wall segment called a weir installed in one of the dam’s spillway bays.
However, recent Oregon Department of Fish and Wildlife research in the South Santiam River shows that many juvenile fish -- particularly steelhead -- are migrating downriver at other times of the year, particularly in October and November.
“We hope this study will give us a better sense of how we can best operate the dam to ensure these fish survive passing the dam as they journey to the sea, and return to the river as adults in a few years,” said Corps fishery biologist Fenton Khan, who is leading the study. “We appreciate the understanding and support of river and reservoir users as we work to achieve that goal.”
The research is part of an ongoing effort to restore Upper Willamette River spring chinook salmon and winter steelhead that are listed under the federal Endangered Species Act.
Foster Dam and Reservoir is one of 13 dam and reservoir projects operated by the U.S. Army Corps of Engineers in the Willamette River drainage system. Each dam contributes to a water resource plan designed to provide flood damage reduction, power generation, irrigation, water quality improvement, fish and wildlife habitat, recreation and navigation on the Willamette River and many of its tributaries.
For more information, visit http://www.nwp.usace.army.mil/Locations/WillametteValley.aspx