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Sunday, June 23, 2019

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Inside race to save Louisiana's first line of storm defense

Inside race to save Louisiana's first line of storm defense

Editor’s note: This is the second of a three-part series on the importance of restoring the state’s barrier islands. The third and final segment will appear in the Sun., Aug. 5 edition.

In 1992, the U.S. Geological Survey, undertaking the first comprehensive assessment of Louisiana's barrier islands, estimated that the islands had decreased in area by an average of 40 percent over the past century.

"A few islands are expected to disappear within the next three decades," the USGS study warned.

Disappear they did. Grand Gosier and Curlew - both part of the Chandeleur Islands on the state's east edge - were a combined 600 acres in 1996. Less than a decade later, they'd been dwindled to just 75 acres. After Hurricane Katrina, they were gone.

In 2005, the coast-wide scope of loss became clear: since the 1880s, nearly 24,000 acres - about 76 percent of the total area of barrier islands - had disappeared, according to the CPRA. That averages out to 200 acres per year.

Change is a constant for barrier islands. They begin life not as islands but as the outer edges of river deltas, dynamic landscapes that naturally shift and retreat and build anew.

Louisiana's barrier islands took shape some 6,000 years ago as the Mississippi River altered course and abandoned parts of its much wider delta. The delta's sandy edges turned into islands as the marshes behind them eroded, becoming what are today Terrebonne and Barataria bays on the delta's west side and Breton and Chandeleur sounds to the east.

The Gulf of Mexico has never been gentle with barrier islands. Waves and wind are constantly scraping at their sides, and storms occasionally break them into bits. But what the gulf took away the river always restored. Silt and sand suspended in freshwater flowed into the gulf and eventually washed up on island's shores.

That changed after humans began to alter the Mississippi, hardening its banks and damming up the sediment-rich rivers that flowed into it. What sediment remained was channeled by levees to flow straight off the continental shelf at the river's mouth.

Meanwhile, climate change is fueling stronger and more frequent hurricanes that pummel the islands. Rising global temperatures have also contributed to the slow upward creep of sea levels - a problem expected to worsen in decades to come.

Subsidence, the gradual sinking of soft delta land, is also at play. Grand Isle, Whiskey and other large barrier islands are dropping by a half inch each year, according to the CPRA.

Then there's the oil industry, which has cut some barrier islands into pieces in the search for untapped reserves. Once torn apart, the islands tend to erode faster. Oil companies have tried quick fixes to shore up islands that support wells and pipelines, but their preferred solution - rock embankments - has only sped up erosion, said Darin Lee, a coastal resource scientist who manages CPRA's barrier island projects. Wave energy bounces off the rock and scours out sand under the water line, making the bank steeper.

"Eventually the rocks collapse, and they sit there, preventing recovery because no new sand can get back to the island," Lee said.

Oil spills also take a toll. The BP Deepwater Horizon disaster in 2010 saturated several barrier islands. Cat Island on the edge of Barataria Bay had been one of Louisiana's four largest nesting sites, hosting dense concentrations of pelicans and other birds. The island's soil soaked up BP oil like a sponge, killing the roots of grasses and mangrove trees. As the plants died, the soil more easily washed away.

Before the disaster, Cat Island was about six acres. Two years later, less than one lifeless acre remained. Now the island is a 10-foot-wide strip of sand that will likely wash away with the next big storm.

The effort to save the barrier islands began not with big-budget projects by the federal government or state but by Terrebonne Parish.

"Look at us on a map - Terrebonne's sticking way out there," said Mart Black, the parish's coastal restoration director. "We're more vulnerable. When there's a storm, we get hit before the others."

In the 1980s, the parish pushed for bigger and better structural protections, eventually getting federal support for Morganza to the Gulf, a network of levees, locks and floodgates under construction across nearly 100 miles of Terrebonne and Lafourche Parish.

Terrebonne's leaders also lobbied for help rebuilding their crumbling barrier islands but got little traction with the U.S. Army Corps of Engineers, the federal agency that issues permits for big coastal projects.

"The Army Corps wanted to study it and study it," Black said. "We said 'no, no, we need something now.'"

Terrebonne Parish engineer Robert Jones dove in, establishing Louisiana's first barrier restoration project in March 1985. It was a low-budget, low-tech affair using dredged near-shore sediment to build protective dikes along the edges of East Island. Atop the island, Jones strung cheap plastic mesh from posts to catch drifting sand. He hired teenagers to plant the new dunes with beach grass. They dragged sticks to make furrows and plopped in seeds from a Coke bottle.

The project rebuilt more than 3,000 feet of 8-foot-high dune, all for about $750,000. The island withstood three hurricanes during its first year and a pounding from Hurricane Gilbert in 1989.

"Terrebonne was the first to show it could be done," Lee said. "The parish gave us our first big push."

The project inspired similar local efforts and served as a blueprint for some of the state's earliest coastal restoration efforts. But Jones, who died in 2002, knew his shoestring approach needed to be scaled up.

"If the U.S. was losing this kind of territory to a foreign aggressor, there'd be no expense spared," Jones told The Times-Picayune in 1992.

But by the late '90s, the Coastal Wetlands Planning, Protection and Restoration Act (CWPPRA) was pouring millions of dollars into barrier island build-ups. Then came the multiple settlements from BP and its drilling partners over the Deepwater Horizon disaster. The billions of dollars in those settlements gave a huge boost to Louisiana's coastal restoration efforts, paving the way for epic projects like the ones on Whiskey and Caminada.

Before the 2010 disaster, barrier island projects averaged less than 3.3 million cubic yards. After 2010, projects had jumped to 5.2 million cubic yards on average, according to coastal engineering consultant Steve Dartez.