Weather, water wage war along Columbia River

Tom Conning

Public Affairs Office

Unrelenting, continuous rains and snow-melt brought western rivers to near-flood or flood stages, including the Columbia and Willamette rivers. The U.S. Army Corps of Engineers and its partners have been managing the incoming water to reduce flood risks and providing support to local and state flood-fight efforts when local resources are exhausted. Those efforts began, in earnest, March 24.

Maj. Gen. Scott Spellmon, Northwestern Division commander (center), Jason McBain, Portland District levee safety manager (left), and John Leighow, Northwestern Division readiness and contingency operations chief (right), discuss a boil on a golf course during levee inspections along the Columbia River, March 28. (Corps of Engineers photo)

The dreary and wet weekend saw the Portland District and its partner, the Multnomah County Drainage District, conducting levee patrols due to the high water on the Columbia River. The teams were looking for areas of concern including levee slides, unusual seepage, boils on the landward side of the levee or ponding.

“County partners requested assistance through the state, which then requested our help,” said Paul Jewell, Portland District flood control and coastal emergency program manager. “Our flood team, a group of 21 dedicated and enthusiastic volunteers are providing support.” “Right now, we’re in a mode of watchful caution and hope to stay that way.”

 

One area of concern was a piece of a levee that was sloughing. Sloughing happens when soil becomes unstable and slides downward. This occurs because the weight of the soil exceeds its ability for cohesion.

Part of a levee in the Bridgeton area of Portland is experiencing sloughing. Sloughing happens when soil becomes unstable and slides downward. This occurs because the weight of the soil exceeds its ability for cohesion. (Corps of Engineers photo)

Although sloughing is a concern, this piece of the levee was not in imminent danger of failing according to Jason McBain, Portland District levee safety manager.

“The current high water certainly demands extra attention to be paid to the levee – which is happening – but for now the levee is stable,” McBain continued. “There were no surprises during the monitoring inspections over the weekend.”

Flooding in some areas is a concern, but water levels are currently more than 10 feet below the Flood of 1996, which saw water overlapping the banks of the Willamette and Columbia rivers in multiple areas. During that flood, those overlapping areas typically didn’t have flood damage reduction structures like levees or berms.

The Corps uses the run-off forecasts produced by the National Weather Service Northwest River Forecast Center to help determine the amount of space needed in its flood storage reservoirs. Year-round monitoring of these forecasts helps the Corps make the timeliest decisions possible to reduce flood risks.