Corps of Engineers considers nature-based flood control

The U.S. Army Corps of Engineers is known for damming rivers and building levees to keep waterways at bay. But a new initiative seeks natural flood control solutions as climate change brings increasingly frequent and severe weather events that test the limits of concrete and steel.

It only makes sense to use Mother Nature’s flood defenses as one of the tools to combat destruction from intense rains in the middle of the country and storms and sea level rise on the coasts, says Todd Bridges, who heads the Corps Engineering with Nature initiative.

Pieces are in place to make the change. In the 2020 Water Resources Development Act, Congress directed the Corps to consider nature-based systems on equal footing with more traditional infrastructure. And the initiative was directly funded for the first time last year with $12.5 million.

Some obstacles

But the Corps is often constrained by its own rules and the way costs and benefits of its projects are evaluated.

“The Corps has a lot of people who are used to doing things a certain way,” said Jimmy Hague, The Nature Conservancy’s senior water policy advisor. “We’re tracking some projects right now where nature-based solutions are almost an afterthought.”

In Missouri, the Corps recently completed a levee setback along the Missouri River after the existing levee was overtopped and breached by flooding in 2019. Rather than simply repairing the levee, the Corps built a new 5-mile stretch farther from the river, opening up about 1,000 acres of floodplain to help reduce future flooding while providing habitat for rare and declining species.

Dave Crane, the Corps’ environmental lead on the project, said making it happen was not simple. The Corps is required to repair levees at the lowest cost, and only extreme damage to the original levee made building a new one possible under its rules.

The Corps also likes to work fast to repair levees before a new flood, and moving the levee required time for planning and acquiring land. The local levee district needed to purchase millions of dollars in farmland that would no longer be protected. With help from The Nature Conservancy and local community buy-in, the Corps constructed the setback, but it’s far from the norm.

Stakes rise

Bridges hopes new 1,000page international guidelines for nature-based systems, five years in the making, will push the Corps to take nature-based solutions more seriously. The manual was developed in collaboration with the Netherlands and the United Kingdom, among others.

The stakes are rising. Over the past five years alone, weather and climate-related disasters cost the U.S. more than $630 billion in damages, Richard Spinrad, head of the National Oceanic and Atmospheric Administration, said when the guidelines were released Sept. 16.

“How we evaluate benefits (of nature-based solutions) is the key issue,” Bridges said. Putting monetary value on their flood protection is a first step. Bridges also wants the Corps to recognize social and environmental benefits not traditionally considered.

For example, he said, a mangrove forest can provide wildlife habitat, enjoyment for people who dive, fish or boat, as well as cleaner air and water. And while concrete floodwalls fall apart and must be replaced, mangroves can grow, affording more protection over time.

“Florida has 500,000 acres of mangrove forest today that provide billions of dollars in flood-risk reduction. How do we sustain or even grow that benefit in the future?” Bridges asked.

Siloed funds

The Corps has rules beyond benefit assessments that complicate its adoption of such solutions.

In Port Fourchon, Louisiana, authorities want to use dredging spoils to restore nearby marshland. But the Corps wants to pump the spoils into the Gulf of Mexico, said Chett Chiasson, the port’s executive director.

That’s because the project’s money comes from the Corps navigation fund requiring the agency to dispose of spoils as cheaply as possible. It doesn’t matter that there is a separate ecosystem restoration fund for projects like the marsh, Chiasson said.

“Their money is siloed, and they can’t put (funds) together in a way that makes common sense,” he said.

GRANT SCHULTE — THE ASSOCIATED PRESS Todd Bridges, a senior research scientist for the U.S. Army Corps of Engineers, walks along a new wetland area that had been flooded in 2019a few miles south of Rock Port, Missouri, on Monday.