PORTLAND, Ore. – The U.S. Army Corps of Engineers alerts neighbors and visitors to Fall Creek Reservoir near Lowell, Ore., that the Corps plans to lower the reservoir’s water level well below normal winter levels this week.
The Corps plans to repeat its 2011 operation of drawing down the reservoir to the original stream channel at 680 feet above sea level, to assist the downstream passage of juvenile spring Chinook salmon listed under the Endangered Species Act. The lower water levels give young salmon a better chance of finding the dam’s regulating outlets and passing through them safely.
The Corps has usually maintained Fall Creek Reservoir’s water level at 728 feet above sea level during past winter flood seasons, but lowered it to 714 feet from 2007 through 2009, 690 feet in 2010, and 680 feet in 2011, resulting in increasing numbers of juvenile salmon passing the dam.
Greg Taylor, aquatic stewardship supervisor for the Corps’ Willamette Valley Project, said that last year’s drawdown attracted at least 20,000 juvenile salmon through the dam, most within a three-day window.
Fall Creek is by far the largest contributor of wild spring Chinook to the Middle Fork Willamette River, and the increasing numbers of juveniles making it downriver to the sea will hopefully be reflected in better numbers of returning adults in the future.
“We have a lot of historical evidence that this is a good method of improving juvenile passage, which in turn increases the number of returning adults,” Taylor said. “From 1968 to 1977 the reservoir elevation was lowered to the streambed and we saw annual returns of 1,000 to 4,500 spring Chinook, versus 90 to 500 fish when water levels were kept higher.”
Fall Creek neighbors and users will notice increased water turbidity. The Corps has closed the reservoir to all boating, including kayaks, rafts and canoes, during the drawdown to protect the public from safety hazards around the dam. Oregon Parks and Recreation Department boat ramps on the reservoir are already routinely closed during the winter months, so impacts to the boating public are minor.
The Corps will return Fall Creek Reservoir to normal winter water levels by February 1 as part of its process of gradually refilling it for the summer conservation season.
Fall Creek is one of 13 U.S. Army Corps of Engineers dam and reservoir projects in the Willamette River Basin. Each dam contributes to a water resource management system that provides flood damage reduction, supports power generation, irrigation, water quality improvement, fish and wildlife habitat and recreation on the Willamette River and several of its tributaries. Since their completion, the dams have cumulatively prevented over $20 billion in flood damages to the Willamette Valley. For more information, please visit http://www.nwp.usace.army.mil/Locations/WillametteValley.aspx.