Poor results for existing diversion in LSU study

David Blake
August 24, 2019 - 4:12 pm
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An LSU study finds Mississippi River diversions may actually do more harm than good for wetlands restoration. The study looked at three different diversions and found land loss, instead of creating or maintaining land.

Coastal Sciences Professor Gene Turner says that runs contrary to the prevailing opinion on how to restore the coast.

"There was no gain from the diversions from any of the three," said Turner

The study looked at Caernarvon, St. Phillips, and Davis Pond diversions and found land loss, instead of creating or maintaining land. 

What happens next?

"I'm not sure what the exit plan is if any of these diversion plans don't work, once they're built, especially the larger ones, it's harder to recover from, if they lose more land," Turner said.

However, other experts point out that the existing diversions were never intended to carry sediment for land restoration. They were meant to decrease salinity of coastal marshes that scientists thought were getting too salty.

"The freshwater diversions are much different than sediment diversions, as we envision them," Bren Haase, executive director of the state Coastal Protection and Restoration Authority, told The New Orleans Times Picayune | The New Orleans Advocate. "They were designed to maintain a specific salinity regime in the basins, and were not at all designed to introduce sediment or rebuild wetlands through mineral accretion."

Caernarvon opened in 1991, Davis Pond in 2002, and St. Phillips was a natural diversion that occurred in 1973.

Turner says that may be because of the significant side effects of introducing so much freshwater to the brackish systems.

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