Louisiana’s Coastal Wetlands Sinking

At the end of the road to Isle de Jean Charles, La., a patchwork of dusty green salt grass and sparkling blue water extends untouched to the horizon.

Stilt-legged egrets wing the sky or stand frozen in the grass. Occasionally, a fat mullet heaves itself out of the water and falls back with a gentle plop.

This beautiful vista is as sure a sign of ecological destruction as the scraped, barren soil of a Superfund site.

A few decades ago, Isle de Jean Charles was a patch of high ground in a sea of grassy marsh teeming with catfish and crawdads. Today, the small community is a true island, regularly flooded during storms and sometimes even at high tide. In a few years, it will be submerged completely.

Deme Naquin, 75, remembers paddling a flat-bottomed pirogue to school as a boy. Now he’s getting ready to leave the only place he has ever called home. The U.S. government has offered to resettle the island’s 270 residents because a new hurricane-protection plan leaves them outside the ramparts.

Some people want to stay. But Naquin and his family are ready to take the government’s offer.

“Another hurricane and the road’s going to be gone,” says Chad Naquin, Deme’s 29-year-old grandson. “It would be hard to leave, but in the long run, it would be the best thing.”

A widely publicized government report recently predicted that sea-level rise caused by global warming could swallow sizable chunks of the coastal United States in the coming century. In Louisiana, that future is already here.

Up to 35 square miles of Louisiana’s wetlands sink into the Gulf of Mexico each year. To date, an area the size of Rhode Island has been lost. In some places, the coastline has retreated 30 miles.

If scientists’ global warming projections prove correct, virtually every state along the Atlantic and Gulf coasts will have problems similar to Louisiana’s by the middle of the century. In a worst-case scenario, sea level would be 44 inches higher 50 years from now. If it is, 23,000 square miles of land along the Gulf and Atlantic coasts will disappear.

Low-lying cities such as Miami, Houston, Wilmington, N.C., and Charleston, S.C., will face many of the same problems that New Orleans grapples with today.

Beyond the United States, low-lying coastal countries such as the Netherlands, Bangladesh and the Bahamas stand to lose large swaths of territory.

“We’re not going to be the only ones in the boat,” says Al Naomi, a project manager in the New Orleans District of the U.S. Army Corps of Engineers. “We’re just in the boat first.”

People have been messing with the landscape of southern Louisiana for centuries, building ever-higher levees along the Mississippi and its tributaries to protect themselves from floods. For the last 50 years, they have even redirected the flow of the river itself.

The results have been catastrophic. South Louisiana requires a constant supply of mud and freshwater to keep itself above sea level, and channelizing the Mississippi River has deprived the landscape of that vital resource.

The Mississippi River literally built southern Louisiana, dropping countless tons of mud at the edge of the continent to form a delta. Over millenniums, the mud washed across the landscape during spring floods, settling in swamps and marshes to nourish plant growth. Every thousand years or so, the river changed course to fill in a nearby low spot.

Eventually the Mississippi built a broad swath of wetlands nearly 300 miles long. If you look at a map of the state, virtually everything south of Interstate 10 was dropped there by the river.

Now mud that would have settled into the swamps of the Atchafalaya or Barataria Bay shoots out into the Gulf of Mexico, never to be seen again. Meanwhile, the land is compacting, slowly turning to clay as it sinks under its own weight and squishes itself dry.

Sinking land due to mismanagement of the Mississippi River and rising sea level caused by global warming work in tandem, erasing Louisiana’s coastal wetlands.

The loss of coastal wetlands threatens to devastate the state’s fishing industry, worth $2.2 billion a year. Fish, crabs, shrimp and other animals rely on wetlands as a nursery, where their young can find plenty of food without exposing themselves to predators. By some calculations, Louisiana’s wetlands are involved in producing as much as 40% of the seafood caught in the United States.

“The biological productivity of the Barataria and Terrebone basins alone dwarfs that of the Everglades, which our country is willing to spend billions to restore,” Ted Falgout says.

Falgout is no rabid environmentalist, intent on saving every square inch of marsh no matter what the cost. As executive director of the Greater LaFourche Port Commission, he manages the country’s largest transportation hub for offshore oil and gas drilling. There are 600 offshore drilling platforms within 40 miles of the port.

The road connecting Port Fourchon to civilization, Louisiana Route 1, sits four feet above sea level for its final 18 miles. If a hurricane were to wash it away, nearly 20% of the total U.S. oil supply would be jeopardized. Gasoline prices might triple, Falgout warns.

More frightening to emergency planners is what a major hurricane could do to New Orleans. High winds and low atmospheric pressure actually raise sea level beneath and in front of a hurricane, sometimes as much as 25 feet. In New Orleans, the only levees high enough to stop a wall of water that big are along the Mississippi, not around the city’s perimeter.

A direct hit to New Orleans by a hurricane with sustained winds above 110 mph would overwhelm the city’s ramparts, filling the city with water as if it were a sinking canoe.

This is far from an abstract threat. New Orleans residents who were children in 1965 remember cowering in their homes during Hurricane Betsy thinking they were going to die. Hurricane Camille, one of the two strongest hurricanes ever to hit the United States, struck Louisiana in 1969 but largely spared New Orleans.

In 1992, Hurricane Andrew hit the sparsely inhabited Atchafalaya basin but still caused significant damage. And in 1998, an evacuated New Orleans was again spared when Hurricane Georges veered east.

The Red Cross estimates that 25,000 to 100,000 people could die if a major hurricane hit New Orleans. The relief agency is so pessimistic about southern Louisiana’s prospects in the face of a major storm that it recently closed all of its relief centers south of Interstate 10, which runs across the state from Lake Charles to New Orleans. Why offer hurricane relief in an area that people are better off abandoning in a hurricane?

Ivor van Heerden, deputy director of the Louisiana State University Hurricane Center, describes a horrific ordeal for anybody unfortunate enough to be in the city when the hurricane hit.

“If you survive the flying debris and your house collapsing,” van Heerden says, “then you’re going to have to deal with a minimum of 13 feet of water.”

Because New Orleans essentially sits in a bowl ringed by its protective levees, that water would stand around for weeks or months until officials could find a way to breach a levee to drain it. The stagnant pool would probably be contaminated with toxic waste from the dozens of petrochemical plants that line the Mississippi, as well as human waste and decomposing carcasses.

“This is a $50-billion disaster,” van Heerden says, surveying the expensive new housing developments on the shores of Lake Pontchartrain. “And in a month, we could have it.”

Experts agree that healthy coastal wetlands provide the best defense against such a catastrophe. Marshes and swamps attenuate the storm surge as it comes ashore, softening the blow to any cities behind them. Experts differ on the exact figures, but a common rule is that traversing 1.5 miles of wetlands diminishes a storm surge by a foot.

With 30 miles of wetlands lost in some parts of coastal Louisiana, a storm like Hurricane Betsy would be far more destructive to New Orleans today than it was nearly 40 years ago.

“Without the wetlands,” Naomi says ominously, “you’re not going to have the city.”

Some scientists believe that they can rebuild the wetlands by further manipulating the Mississippi. A coalition of 11 state and federal agencies has assembled a plan called Coast 2050 and is lobbying the U.S. Congress to foot a major part of the $14-billion price tag.

Coast 2050 would divert Mississippi water into dying wetlands. It would shore up barrier islands and plug canals that allow saltwater to penetrate freshwater marshes. It proposes erosion control projects, plantings to help establish new wetlands and breakwaters to protect fragile coastlines.

Its proponents say Coast 2050 will prevent another Rhode Island’s worth of wetlands from being washed away by the middle of this century.

But will it work?

Van Heerden dismisses the plan as an unscientific “shopping list” that doesn’t sufficiently imitate the natural functions of the Mississippi River system.

“It was basically put together by bureaucrats,” he says.

And politics might prevent many of the Coast 2050 proposals from ever being built. The Davis Pond diversion, a demonstration project upstream of New Orleans, is still not operating almost 40 years after it was first authorized. Fishermen who worried that freshwater spilling into the marsh would ruin their catch filed lawsuits that took years to settle, and local residents concerned about flooding demanded design changes. Meanwhile, thousands of acres of wetlands have been lost.

In his SUV, cruising along Interstate 10 just inches above the marsh, van Heerden surveys a landscape that is already below sea level and envisions a bleak future.

“This is a lesson for many other states that have coastal wetlands,” he says. “The problem, unfortunately, is only going to get worse.”