Scientists hope a sediment-laying strategy can help preserve the marine highway while restoring marshlands
By Mac Carey, Undark
The U.S. Army Corps of Engineers along with other experts, hopes that placing a thin layer of dredged sediment over the top of the marsh will help them gain ground, literally, in the fight to save the saltwater marshes that flank the Intracoastal Waterway. The 3,000-mile water passage runs along the East and Gulf Coast, and it’s one of the busiest inland waterways in the United States.
“It would be a benefit for both worlds,” said Army Corps of Engineers biologist Erica Janocha, who helped manage the project. She was referring to the two-fold opportunity: find a use for sediment dredged from the increasingly shallow Intracoastal Waterway to ensure it’s deep enough to navigate, and build up the drowning marshlands surrounding it.
Salt marshes like the one along Jekyll Creek serve as buffers between water and land, putting them on the frontlines of climate change; over the last century, salt marsh habitats lost half their global coverage, due in part to rising seas. And in Georgia, the state’s low shoreline geology means some marsh areas may soon get overtaken by the sea.
After dredging and TLP is complete, the salt marsh is covered in a mixture of fine-grain sediment called pluff mud. Visual: U.S. Army Corps of Engineers, Savannah District
Dredging itself can exacerbate the erosion of marsh edges, since it encourages faster and more extreme tidal changes. However, the biggest challenge with dredging is where to put all the resulting sediment. As government funding has increased for the waterway— the Corps has devoted roughly $150 million to operating and maintaining the southern portion since 2022, according to the Atlantic Intracoastal Waterway Association — so has the amount of sediment.
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