Posted on July 10, 2024
On a random morning in Grand Isle, charter boat captain Mike Guidry watches the surf pound against a series of segmented rocks that guard camps near the beach.
“People always associate hurricanes with destruction,” said Guidry as he surveyed the rocks from his boat. “Well, we have stronger cold fronts.”
Guidry credits the rocks, which were installed in recent months, with providing a new layer of protection.
“Where the water was right up against the camps after the hurricane, it would just continuously beat on all of that,” Guidry said.
In a fight for survival, Grand Isle has deployed segmented rocks over the years, especially along the beach on the Gulf of Mexico.
The technique has a powerful believer in Gordon Dove, the new chairman of the Louisiana Coastal Protection and Restoration Authority.
Dove argues the segmented rocks allow wave action to carry sand through gaps, trapping sediment behind them as the waves recede.
“This went through (Hurricane) Ida,” Dove said, pointing to a slide showing a portion of sandy beach along the island’s levee.
“My vision is to rebuild the coast through segmented breakwater rocks from Texas to Mississippi,” Dove said.
Skeptics, including Alisha Renfro from the National Wildlife Federation’s Gulf of Mexico Program, argue the technique is not universally effective along Louisiana’s coast, where rocks often sink after they’re installed.
“There are certainly places where we can continue to build that out, but it’s not the one solution that works everywhere,” said Renfro.
Renfro cautions it is important to understand where rocks work, where they fail, and why.
“The problem with our coast is that there isn’t enough sediment,” Renfro said. “So, it just is not going to work every single place.”
While agreeing segmented rocks are beneficial in Grand Isle, Renfro said the geology of Louisiana limits their effectiveness along its coast.
“The thing about rocks is we don’t have rocks here in Louisiana,” Renfro said. “We have to go other places to get rocks, and when you put it on our wet, muddy sediments, they sink over time.”
Wherever possible, she argues for the use of oyster reefs, living shorelines that can act as rock barriers and build themselves up over time to fight rising seas. Dove disagrees.
“If you have a current offshore, they work,” Dove said. “When you use them inshore, they’re simply to stabilize.”
The debate is part of a much broader discussion about Louisiana’s effort to protect and restore its coastline and its devotion to its science-based Coastal Master Plan.
Since Hurricanes Katrina and Rita, the plan has guided the state’s coastal priorities.
However, Gov. Jeff Landry’s administration has questioned the centerpiece of that plan, the Mid-Barataria Sediment Diversion, especially in light of the project’s $3 billion cost.
“One of the big strengths that Louisiana’s had in this land loss crisis is that we have used science to guide what restoration projects we should do, what restoration looks like in our state,” Renfro said.
Dove pointed to the effective use of rocks at Rockefeller State Wildlife Refuge south of Lake Charles. When rocks sank in the soupy soil, refuge managers used a novel approach to overcome the challenge. Construction crews first laid down a lighter, aggregate material, then covered it with rocks. The reduced weight allowed the structures to stay in place and protect several miles of fragile beach.
“If an engineer would come back and say you don’t need rocks at this island, we wouldn’t fight them,” Dove said.
Dove notes the U.S. Army Corps of Engineers would have to sign off on the use of segmented rocks along other sections of the coast.
