News Release
| Release Number: | 06-003 |
| Dated: | 1/5/2006 |
| Contact: | Heidi Y. Helwig, 503-808-4510 |
Portland, Ore.—The U.S. Army Corps of Engineers will release large amounts of water on Friday from its reservoirs on the Middle Fork of the Willamette River and the North Santiam River to prepare for future rain storms.
Friday morning, Jan. 6, Corps water regulators will gradually increase releases from Big Cliff Dam on the North Santiam River to 12,000 cubic feet per second (cfs), increasing water elevations at the Mehama gage to about 8.1 feet by Friday evening. At about the same time, releases from Dexter Dam on the Middle Fork of the Willamette also will be gradually increased to 12,000 cfs, raising water elevations at the Jasper gage to about 8.8 feet by Saturday, Jan. 7, said Karl Kanbergs of the Corps’ Reservoir Control Center, the nerve center for Willamette River water regulation.
The increases are necessary to get ready for rain storms projected for early next week. Lookout Point and Detroit dams, which feed into Dexter and Big Cliff reservoirs, were 50 percent and 63 percent full, respectively, as of midnight on Jan. 4, Kanbergs said. Normally the Willamette projects are held at minimum levels in the winter to capture rises in inflows due to rain. Flows will remain high on the Willamette mainstem, especially at Harrisburg and Salem, but below peak levels experienced last weekend, he said.
“This is the largest release of water from these dams in quite a while,” Kanbergs said. Though releases as high as 10,000 cfs of water below Dexter Dam has caused localized flooding in the past, “the best information we have today indicates that modifications to Corps revetments will now allow us to release up to 15,000 cfs without the threat of downstream flooding in these areas, other than the low-lying access roads,” he said.
While Dexter and Big Cliff dams will experience the largest releases of water over the weekend, the Corps also is releasing water from its remaining Willamette Valley reservoirs to regain flood damage reduction capability, Kanbergs said. Currently, the releases from the reservoirs exceed the amount of water coming into the reservoirs from rain or runoff, he said. This allows the reservoirs to draft out the water that was stored during the last big storm, he said.
For daily reports of water inflows and outflows, as well as the current elevation of each Corps reservoir in the basin, click on “Daily Report” on the Corps’ web page at: http://www.nwd-wc.usace.army.mil/nwp/reports.html.
While Corps dams only control 27 percent of the water that flows through the Willamette River Basin, the results are impressive. Fern Ridge Dam on the Long Tom River, for instance, reduced flows as far north as Salem by more than half a foot, Kanbergs said. Following the last big rainstorm, the peak flow at Salem reached about 141,000 cfs or elevation 26.8 feet, he said. “Without Fern Ridge Dam, we estimated it would have caused Salem flows to reach about 148,000 cfs or elevation 27.4 feet. All 11 storage dams were operated together to drop Salem from an estimated peak elevation of 36 feet – almost 1 foot higher than flows during the flood of 1996.” Work to repair a failing drainage system in Fern Ridge Dam was completed in November 2005.
During the flood damage reduction season--between mid-November and Jan. 31 for the Willamette River Basin--the Corps' goal is to operate all of its reservoirs to reduce flood damages downstream while still maintaining safe amounts of storage space in the reservoirs.
In addition to minimizing flood damages, Corps reservoirs are operated for hydropower, irrigation, fisheries, water supply, water quality and recreation. The Corps' goal is to effectively balance these competing needs to serve the region and its people.