Corps of Engineers repairs Nooksack River levee damaged in this once-in-a-career event
Repairs have begun on a damaged levee south of Ferndale that caused flooding and evacuations of the Marietta area on Christmas morning.
The 200-foot breach on Dec. 24, 2022, was likely caused by a combination of factors including a king tide, cresting rivers and ice flow caused by freezing temperatures, according to Kieth Rudie, acting chief of Emergency Management in the Seattle District with the U.S. Army Corps of Engineers.
The breach was at a section of the levee along the Nooksack River just south of the Slater Road bridge.
The breach was first confirmed by members of the Lummi Nation, who saw it on a drone flyover, according to Rudie. On Dec. 29, the Lummi Nation declared a state of emergency following the levee breach, although a news release from the Lummi Nation said it is likely the worst of the flooding has passed.
The river breached the same levee in a slightly different spot last year, according to Rudie. He estimates the cost to repair the levee will be a few hundred thousand dollars. Repairs are scheduled to be completed later this week.
The levee is made of piled earth and rock, and is essentially an upgraded river bed. When the river overflowed and came over the levee it damaged the levee, lowering it by four to six feet. Repair crews are working to bring more earth and rock to the levee, filling in the holes and rebuilding the levee to the original height.
“What happened here is that sometime between 10 p.m. and midnight, Christmas eve, the ice in the river jammed up and released here (the levee). This is the (likely) result of an ice flood burst, and the trees were barked from the ice flowing over the levee and what was remaining of the levee,” said Gary Goodall, a former river and flood engineer for Whatcom County. “I have not seen this in 40 years of working on the river and being around the Nooksack. We have had ice two or three times, but not an ice jam debris flow. This is a once-in-a-career event.”
Goodall is retired, but still comes in to help when he is needed.
What made this flood unique was the ice involved. Not only did the river overtop and burst the levee, but the water was full of ice, stripping the trees of bark and making the flood even more dangerous.
The exact time and cause of the river topping the levee is unknown, according to Rudie.
The river overtopping the levee created a scour hole, which caused a breach in the levee. A scour hole occurs when falling water carves out a section of earth, similar to digging a hole in a flower bed with a garden hose. In this case, the floodwaters from the river topped over the levee, and came crashing down on the other side, digging a hole and breaching the levee.
The levee moves hundreds of feet parallel to the Nooksack River, to limit flooding. The Nooksack, like all rivers, twists and turns through the county. The damaged section of the levee came at a turn following a long straight length of river, so the water crashes into the levee at high speeds.
There were also a number of unconfirmed reports that the river was blocked by something, according to Rudie. This seemed likely because the river gauge in Ferndale, a device used to measure the height of the river, was showing an increase, but the river didn’t seem to be flowing. Goodall said he was in the room, watching the gauge as this happened.
“The notion of an ice dam seems reasonable because the river rose very rapidly in less than an hour’s time, and then the gauge dropped,” Rudie said. “Ultimately, what appears to have happened is that the river did back up to a point where it overflowed.”
This story was originally published January 3, 2023 at 10:21 AM.
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