Oil spill could hasten loss of Louisiana's marshes

Todd Farrar with SCAT (Shoreline Cleanup Assessment Team) holds up hard tar balls found on the beach in Pass Christian, Mississippi May 12, 2010.

PORT FOURCHON, Louisiana (Reuters) - As blobs of tar wash up on Louisiana's outer shoreline three weeks into a huge oil spill, the focus is on protecting the fragile, disappearing marshes at the heart of much of the state's economy and culture.

"The vegetation in the coastal area is like the glue that holds the sand and the mud together," said Garret Graves, who chairs the state's Coastal Protection and Restoration Authority. "So you lose that vegetation, and you have mud."

The steady erosion of Louisiana's fragmented shoreline and marshlands over the years, hastened by a recent string of powerful hurricanes, will be accelerated further if the oil spill in the Gulf of Mexico spreads into the state's vulnerable estuaries, experts say.

Oil can be removed relatively easily from the surface of sand but it is toxic to plant life.

Racing against time, Louisiana Governor Bobby Jindal this week ordered an expansion of work by National Guard troops to close shoreline breaches in some 40 areas that have left marshlands exposed to immediate oil infiltration.

He also is seeking emergency federal approval for a permit to create large "sand booms" -- man-made barrier islands -- from sand that would be dredged from the Gulf floor in three zones off southeastern Louisiana. He said such an operation could start to produce new land 10 days after dredging starts.

At stake is the ecological foundation of an economy and a way of life.

The vast but dwindling marshes are the spawning grounds and nurseries for shrimp, oysters, crabs and fish that make Louisiana the leading producer of commercial seafood in the continental United States and a top destination for recreational anglers. The state dubs itself the "Sportsman's Paradise".

"If the oil comes in here ... this will be a Sportsman's hell hole," said Rodney Dufrene, 23, a shrimp boat owner from a town called Cut Off in La Fourche Parish.

A PROBLEM DECADES IN THE MAKING

Graves said the "sand boom" dredging plan seeks to quickly restore some of what has taken decades to disappear.

Until the 1930s, silt and sediments carried down the Mississippi River and deposited in the delta added nearly one square mile (2.6 sq km) a year to Louisiana's land mass, most of it marsh.

But during the past 80 years, with the advent of levees to control the flow of the Mississippi, as well as dredging and the channelization of the river for navigation, the state has lost about 2,300 square miles (6,000 sq km) of its coastal lands as silt washes straight out to sea.

"The result of that is a very, very fragmented shoreline, a very deteriorated barrier coastal area," Graves said.

As an illustration, Graves noted that the rim of Louisiana's coastline is nearly 400 miles long, but the actual tidal shoreline -- accounting for the patchwork of islands, bays, inlets and channels -- amounts to over 7,700 miles.

As the state's outlying islands shrink and disappear, the Gulf's sea water has pushed farther north into estuaries, killing vegetation accustomed to brackish, less salty water.

The rapid growth of onshore oil and gas facilities and other development also has taken a toll.

But the whole process was intensified by a flurry of hurricanes in the last several years -- including Katrina and Rita in 2005, and Gustav and Ike in 2008.

The storms punched new holes through barrier islands and coastal beach, exposing even more marshland to saltwater intrusion and leaving wetlands especially vulnerable to the latest calamity, an undersea gusher spewing at least 5,000 barrels of crude into the Gulf unchecked daily since April 20.

"The land is holding on by its fingernails," said Cathy Norman, manager of the Edward Wisner Donation land trust that owns property leased by the Port of Fourchon, the principal supply harbor for the Gulf's deep-water oil and gas industry.

"It's just ready to fall apart, and if oil gets in here and the plants die off, we're going to have just all water," she said. "Sand is real easy to clean up. Marsh is not."

The oil industry, too, has plenty to lose. Norman said Port Fourchon, a hub for 60 percent of the U.S. crude supply, has seen an average coastal retreat of nearly 50 feet a year.

Norman said she hopes the current crisis in the Gulf will help build support for coastal restoration projects like one she oversaw about six years ago, a $500,000 endeavor in which volunteers put in 27,000 plants to reclaim 50 acres of Port Fourchon.

"It can be done," she said.

(Editing by Ed Stoddard and Sandra Maler)