BELLE CHASSE, La. (AP) — Louisiana has completed one of its biggest coastal restoration projects yet, and is at work on even bigger ones.
The dredge used to suck up sediment from the Gulf of Mexico to add 1,000 acres (405 hectares) of habitat to sites in the Terrebonne Basin is now at work in the Mississippi River, doing the same for a 1,600-acre (650-hectare) project that's further east and named for a historic Plaquemines Parish outlet called Spanish Pass, officials said last week.
“These are key examples of our frontline defense” against hurricanes, said Bren Haase, executive director of the state Coastal Preservation and Restoration Authority.
They had been eaten away by erosion and subsidence — and by sea level rise, which, like hurricanes, is made worse by climate change.
On Tuesday, the authority announced completion of another project — the addition of about 256 acres (104 hectares) of beach and dune and 143 acres (58 hectares) of marsh on West Grand Terre Island.
Barrier islands and marshes slow storm surge, so the work protects people and buildings on shore while providing habitat for plants and animals.
The Spanish Pass project starts just outside the Plaquemines Parish town of Venice.
The fragility of the wetlands fringing Louisiana's coast was illustrated less than a minute by seaplane from the project's west end. In that spot, trees grow in parallel lines on relatively high ground in open water. They mark the banks of canals dredged through marshes that no longer exist.
The state's biggest restoration project so far was 1,200 acres (485 hectares) completed in 2010 in the upper Barataria Basin, the authority's deputy director, Greg Grandy, said in an email. And work began in January on the nearly 2,800-acre (1,100-hectare) Lake Borgne Marsh Creation project near Shell Beach in St. Bernard Parish.
“The more land I have between me, wherever I’m standing, and the Gulf of Mexico as a hurricane is approaching, the better I feel, the better off we are,” Haase said. “Those natural barriers are very, very important.”
The Terrebonne Basin project increased the size of Timbalier and Trinity-East islands and West Belle Headland as well as creating 8.6 miles (14 kilometers) of beach. It took about two years, partly because of hurricanes in 2020 and 2021.
Hurricane Zeta in 2020 and Hurricane Ida last year both crossed the work area, Haase said.
He said work to enlarge Trinity East Island was completed before Ida hit on Aug. 29, and it stood up well to the storm. However, Ida damaged incomplete work on West Belle Headland — an area that also had been worked on in 2018 to repair damage from Hurricanes Katrina and Rita in 2005.
The dredge is now working to create of seven miles of marshes backed by ridges in an area west of Venice. The ridges, high enough to be planted with trees, are designed both to protect the new marshes from erosion and to slow storm surges heading toward shore.
The project will take 10.8 million cubic yards (8.3 million cubic meters) of sediment — enough to fill the Empire State Building nearly eight times.
Money paid by BP LLC after the 2010 oil spill is funding the current projects.
The Terrebonne Basin project cost $166 million. The Spanish Pass and West Belle Terre projects are about $100 million each, the Lake Borgne project is about $61 million.
The Barataria project, completed about a month before the spill, cost about $36 million.
Follow AP coverage of climate change and the environment: https://apnews.com/hub/climate-and-environment.