Scientists with the U.S. Geological Survey and the state have been closely monitoring Louisiana’s wetlands. They’ve set up nearly 400 sampling stations, each a square kilometer in size, to track the change. For many of the brackish and saltwater marshes near the Gulf of Mexico, there’s been a clear uptick in land losses since around 2015.
Chart shows estuarine marshes in the Terrebonne, Barataria, Breton Sound, and Pontchartrain basins. Source: Couvillion, B.R. (2023)*
Estuarine wetland area
in southeastern
Louisiana
1,600
sq. mi.
Chart shows saltwater and brackish marshes in the Terrebonne, Barataria, Breton Sound and Pontchartrain basins.
Source: Brady Couvillion
Estuarine wetland area
in southeastern
Louisiana
1,600
sq. mi.
Chart shows saltwater and brackish marshes in the Terrebonne, Barataria, Breton Sound and Pontchartrain basins.
Source: Brady Couvillion
1,600
sq. mi.
Estuarine wetland area
in southeastern
Louisiana
Chart shows saltwater and brackish marshes in the Terrebonne, Barataria, Breton Sound and Pontchartrain basins.
Source: Brady Couvillion
“This is becoming a trend that we’ve seen for six or seven years now,” said Brady Couvillion, a coastal geographer with the U.S. Geological Survey who charts the wetland changes. “It’s definitely piqued our interest.”
In the lower Breton Sound region, losses are happening even faster. More than 8,700 acres have vanished since 1985, according to USGS estimates — and much of that loss has come over the past decade.
Map comparing the extent of wetlands in the Breton Sound and Mid-Barataria regions to the south-east of New Orleans in 1985 and 2020
Lake
Ponchartrain
New
Orleans
Breton Sound
wetlands
Barataria
wetlands
Lake
Ponchartrain
New
Orleans
Breton Sound
wetlands
Barataria
wetlands
Lake
Borgne
Lake
Ponchartrain
New
Orleans
Breton Sound
wetlands
Barataria
wetlands
Louisiana’s wetlands shrank dramatically after being torn up by Katrina and other hurricanes in the 2000s. But a recovery appeared to be underway by 2010. The trend reversed about five years later, suggesting the sudden bout of sea level rise could be a major factor.
In middle Barataria, wetlands up against the ocean are receding, leading to overall loss. But marshes farther from the sea are growing in elevation, like a healthy wetland should.
Glover’s father died in 2007. She knew her dad, engineer John Edgar Land, had been a longtime state employee. But it wasn’t until last year that she learned he’d apparently been involved in designing the state’s first large engineered river-diversion project, constructed long before the current race to defend the coast.
In an old box she found in her brother’s house, Glover discovered plans for the Bayou Lamoque Freshwater Diversion. Built in the mid-1950s to help oyster fishermen by driving back salt water, it contained gates that lifted to channel up to 4,000 cubic feet of fresh water per second into the marshes behind it.
Locator map that shows the location of the following map within Louisiana
New
Orleans
New
Orleans
New
Orleans
Map showing the location of a freshwater diversion built in the 1950s between the Mississippi River and Breton Sound
Breton
Sound
Freshwater diversion
built in the 1950s
Source: Satellite imagery via Planet Labs PBC
Breton
Sound
Freshwater diversion
built in the 1950s
Source: Satellite imagery via Planet Labs PBC
Breton
Sound
Freshwater diversion
built in the 1950s
Source: Satellite imagery via Planet Labs PBC
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