News Release
| Release Number: | 00-167 |
| Dated: | 9/15/2000 |
| Contact: | Public Affairs Office, 503-808-4510 |
Corps and Contractors combat shoals in Columbia River Channel
Portland, Ore. – The U.S. Army Corps of Engineers and contractors are combining forces to combat shoaling in the Columbia River. The Corps' hopper dredges Yaquina and Essayons, along with the Port of Portland's pipeline dredge Oregon and Natco Dredging's Dodge Island are working to remove shoaling built up in the navigation channel.
The Yaquina is currently working near Miller Sands at about River Mile 20 and will move upriver when that area is cleared, and the Essayons is dredging near Sauvie Island and then will move to the Longview, Wash., area. The Oregon is working near Puget Island at about River Mile 40, and the Dodge Island is dredging at the mouth of the Columbia River. All are removing shoaling that has built up in the channel and is causing shippers and river pilots concern during this typically low water time of the year. This year, those levels are even lower than normal.
In 2000, there are lower than usual water levels because of a low snowpack and thus low runoff in the entire Columbia River Basin, which extends from Canada, into Montana, and covers much of Oregon, Washington and Idaho. Water volume measurements taken at The Dalles Dam, near The Dalles, Ore., indicate runoff was 93 percent of normal from January through July 2000, and down to 90 percent of normal from April through August 2000.
The Corps' Portland District develops annual maintenance dredging plans that use contract and Corps dredges to keep the navigation channel at its authorized 40-foot depth, to ensure navigability to 55 feet over the Columbia River Bar, and in other channels and harbors up and down the Coast. Each year, typical dredging needs for the year are evaluated, then specifics developed from hydrosurveys. The District's hydrosurvey boats monitor the entire channel each month year-round, and based on shoaling action and “sand wave” changes, help determine priority dredging areas, in accordance with the annual plans.
All hydrosurveys are provided to the Columbia River Pilots to allow them to navigate the channel safely in areas where shoaling has built up. The pilots, who are able to feel subtle depth changes as they travel the river, also report possible shallow areas to the Corps so that each area can be considered as dredging plans are continuously adjusted.
“Determining exactly where we dredge at any given time and with what dredge, is always a juggling act,” said Steve Perkins, chief, Channels and Harbors Project, Portland District. “There is always a lot of scattered shoaling and sand wave movement in the Columbia River and this year there have been more sand waves than is typical. Flow volumes and velocities seem to have the greatest affects on shoaling and sand wave movement. Also, this year the river level is significantly lower than usual even during this low water time of the year. During the last few days, based on the latest hydrosurveys and reports from the pilots, we've adjusted our dredging plans. We called the Yaquina, which was working on the Coast, back to work in the Columbia. It will return to the Coast when work in the Columbia is completed. Our goal is to be responsive to the needs of the river users, and to maintain the channel at the authorized depth.”
This week the Pilots Association put out a notice that ships navigating the river during this low water need to draft no more than 38 feet because of the shoaling, combined with the lower than normal water level. The pilots and Corps continue to coordinate closely so ships can avoid what could be compared to potholes in the highway, but in reverse. As those avoidance actions are taken and draft guidelines followed, the dredges are working to capacity to diminish the shoaling in various areas along the river as quickly as possible.
A full dredging schedule and multiple requirements means not all areas in the 106-mile-long channel between the ocean and Vancouver can be covered at once. This year, Mother Nature inserted herself in the process, creating more concern than usual. The Corps is coordinating closely with the Columbia River Pilots Association, the shipping industry, and the U.S. Coast Guard.
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