Army Corps flood fighters continue work in Idaho |
| May 22, 2011 |
|
SEATTLE – The Army Corps of Engineers’ Seattle
District has flood fight teams out in three
river basins, and the Corps' Emergency
Operations Center is under 24-hour operation as
rivers remain high. In Kootenai County a flood team is assisting county efforts to prevent Hayden Lake Dam from failing by strengthening the existing structure, which was actively eroding. Construction began May 15 and is expected to continue through Friday. In the Yakima basin, at the request of Yakima County, teams have completed work to shore up a weakened portion of the Nile levee, which was constructed during the 2009 Nile landslide on the Naches River to protect Highway 410. Teams have also completed work on an area of the federally constructed levee on the Yakima River near Terrace Heights and the levee protecting the sewage treatment plant. The team also raised the City of Naches levee and provided assistance on the previously damaged Rock Creek Levee on the Naches River. A team is on the St. Joe River to provide technical assistance to St. Maries as the St. Joe River remains high. The Corps finished assisting Lincoln County with work at Bay Horse Dam on Miller Lake. When Corps and Lincoln County team members arrived on site May 13, the dam was overtopping by 3 to 6 inches at each of the abutments and at the center, and two other low spots. A swift water search and rescue team had deployed to open the 40 inch outlet pipe out of the structure, which had become plugged – there was very little water flowing out, and there was failure occurring around the outlet structure. Only about half could be opened to flow, with additional debris threatening to plug the outlet on the upstream side. The overtopping was causing erosion of the face of the dam when the Corps arrived on site. The team worked until midnight to place 1-2 rows of sandbags across the top of the dam and built an overtopping spillway using sandbags and plastic sheeting. The outlet was cleared and is now flowing and working well, and the level of water behind the dam continues to drop. The Corps has distributed 291,000 sandbags to date in western Montana and northern Idaho, and provided a pump to the town of Cataldo, Idaho, which faces flooding from the Coeur d’Alene River, and another pump is on stand-by for the Pend Oreille. On Monday the Corps began reducing outflows from Libby Dam from 20,000 cubic feet per second to 16,000 cfs. The Libby Dam outflow reduction should help to keep the stage below 1,764 feet at Bonners Ferry while the local inflows remain high. This morning flows into Lake Pend Oreille were 100,000 cubic feet per second and the Albeni Falls Dam was passing 70,000 cfs in free flow operation. Flood stage at Newport is 100,000 cfs, a stage elevation of about 2,046 feet. The lake elevation is above 2,058 feet and rising. Flood stage on the lake is 2,063.5 feet. Public meetings to discuss Pend Oreille flood risk are being held May 18 in Sandpoint, Idaho, and May 19 in Cusick, Wash. Additional flood teams for eastern Washington, western Montana and northern Idaho are on alert. Current flow information for many of the river basins in the Northwest may be found here: http://www.nwd-wc.usace.army.mil/nws/hh/index-j.html. |