Restoring our coast

Louisiana’s first line of defense
Published: May. 29, 2019 at 2:52 PM CDT
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(WAFB) - Louisiana has lost about 1900 square miles of land since the 1930s.

Restore the Mississippi River Delta, a coalition of groups looking to slow that trend, recently took First Alert Storm Team’s Dr. Steve Caparotta up for a bird’s eye view of the fight to save our coast.

Flying over the Mississippi River Delta, it can be tough to distinguish where the coast ends and the Gulf of Mexico begins. Our coast was built and shaped over the course of thousands of years, largely by natural meanders in the Mississippi River and its periodic floods that would deposit land-building sediment, but man changed that in the 20th century.

"The Mississippi River, we tamed it in order to benefit navigation, in order to prevent floods from happening,” explained Dr. Alisha Renfro with National Wildlife Federation. “But at the same time, we’ve shut off the natural processes that built most of coastal Louisiana and by doing that, we’ve starved our wetlands of sediment and now they’re dying.”

The Bohemia Spillway, located just downriver of Pointe à la Hache in Plaquemines Parish, provides a living laboratory for studying the Mississippi’s impact on the coast.

On the west side, man-made levees contain the river, but on the east side, there are only natural levees, allowing the river’s sediment-rich water to spill into the marsh, as clearly seen by that muddy appearance during our flyover.

“You see a marked difference between the marsh. You have much more whole, greener, lusher looking march on that east side of the river that gets sediment versus in some cases, no marsh on the western side. There’s water up against the back levee,” said Dr. Renfro.

Levees are only part of the problem, with factors like hurricanes, sea level rise, subsidence, and many others certainly playing a role in land loss. But from our bird’s eye view, the most obvious is the labyrinth of man-made canals and channels, many of which were created decades ago for oil and gas purposes. ​

“When you dig a canal, you’re destroying wetlands directly as you dig the canal," said Dr. Renfro. "You also change how the water flows through the system and you can create avenues where saltwater can get into freshwater wetlands, so they can have some far-reaching effects.”

The number of canals dug over the last century to tap into Louisiana’a natural resources is astounding, estimated to be around 35,000.

“It’s enough to go around the earth three quarters of the distance around the earth at the equator,” said Dr. Eugene Turner, a professor at LSU’s College of the Coast & Environment.

He believes there’s a relatively inexpensive opportunity to restore some of our wetlands by back-filling some of the more than 27,000 abandoned canals. In simple terms, it involves dragging the dredged material on the spoil banks back into the canals and letting nature get to work.

“You could do it for $330 million. That’s pretty small compared to the amount of money that people have gotten out of these wetlands," said Dr. Turner.

Dr. Turner’s idea is simply that right now, just an idea. but other coastal restoration efforts are much further along. Two large-scale sediment diversion projects, the Mid-Breton Sediment Diversion and the Mid-Barataria Sediment Diversion, will aim to take advantage of times like now when the Mississippi River is running high.

“The fundamental issue facing Louisiana is a lack of sediment input,” said Bren Haase with the Louisiana Coastal Protection and Restoration Authority.

That sediment is seen as land-building gold by many coastal scientists, but it doesn’t come without controversy, especially from fishermen that could be impacted by the diversions.

“We need to embrace the saltwater marsh that we have and do what we can to keep it around, not kill it with a bunch of freshwater,” said Niko Tesvich, a commercial fisherman.

But with each day that passes, more of our coastline is lost, and Governor John Bel Edwards has made it clear he’s ready to move forward with some of these projects.

"This is a threat to two million people who live and work along the coast. We are going to move forward because there is a sense of urgency,” said Edwards.

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