News Release
| Release Number: | 06-044 |
| Dated: | 3/31/2006 |
| Contact: | Jennifer A. Sowell, 503-808-4510 |
PORTLAND, Ore. - The U.S. Army Corps of Engineers will increase outflows from some of its Willamette Valley reservoirs over the next few weeks to protect endangered species of migrating fish.
The Corps has begun to adjust releases from its reservoirs to ensure that flows in the main stem of the Willamette River stay above levels needed to maintain healthy populations of salmon, steelhead and other fish species. The spring flows are an annual operation requested by the Oregon Water Resources Department, Oregon Department of Fish and Wildlife, and National Marine Fisheries Service.
The minimum flow targets as measured at Salem are 20,500 cubic feet per second (cfs) for the first two weeks of April. As of noon, Thursday, the Willamette River’s flow at Salem was 18,700 cfs. The Corps will increase reservoir releases to make up the difference by Saturday.
The greatest increases will likely occur at Lookout Point, Green Peter and Foster dams, while other projects will be adjusting flows slightly depending on weather conditions and inflows. Releases are adjusted very gradually so no safety hazards are expected, however, changes in water levels may be noticeable downstream of some of the dams. These flows will vary depending on the weather. An increase in precipitation or warmer weather, which causes the snowpack to melt more rapidly, would be expected to increase natural streamflows. Although Detroit Dam is not being used to augment the Salem flows, it’s outflow will increase from 1,000 to 1,500 cfs in order to provide adequate spawning habitat for winter steelhead in the North Santiam River.
According to Greg Bowers, hydraulic engineer for the Reservoir Control Center, the changes are not expected to affect the Corps' ability to store enough rain and snowmelt to have full pools, or nearly full pools, in the reservoirs for the summer recreation season.
"Our main stem target flows decrease to 17,800 cfs by April 16 and 15,000 cfs by May 1, and the basinwide snowpack is about 126 percent of average,” Bowers said. "Both of these factors increase the likelihood that the reservoirs will fill, or nearly fill, despite the increased releases."
This year, boating facilities at Detroit and Fern Ridge, including marinas, are expected to be usable by mid- to late-April.
During the two week period beginning Monday, April 1, Foster Lake will be drafted to near its minimum pool elevation so crews can install a weir in one of the dam's spillway gates. The operation, which takes place every year at this time, is designed to help migrating winter steelhead move past the dam on the journey to the Pacific Ocean. The reservoir will be refilled and available for recreational use by the Memorial Day weekend.
The Corps coordinates a delicate balancing act when managing its multiple purpose projects. In the summer, two of the primary competing needs are recreation and fisheries. In addition, other authorized purposes of Corps projects include flood damage reduction, hydroelectric power production, irrigation, navigation, and municipal and industrial needs.
The Willamette Valley reservoirs include: Big Cliff, Detroit, Green Peter, Foster, Fern Ridge, Blue River, Cougar, Fall Creek, Dexter, Lookout Point, Cottage Grove, Dorena and Hills Creek. For more information about current water levels and accessible boat ramp elevations, visit, http://www.nwd-wc.usace.army.mil/nwp/.