Related: Regional Insurance Coverage for the Southeast/Gulf Coast

Jeff Hingle, sheriff of Plaquemines Parish, a delta sliver just outside New Orleans that's home to Belle Chasse and fishing communities, said the parish runs the risk of becoming “an island in the Gulf” if action isn't taken.

This sliver of land was formed only about 600 years ago when the Mississippi River changed course and began building up the present delta.

In many places, Plaquemines already looks like an island in the Gulf.

During a tour Tuesday of the parish's badly eroded marsh, deputies pointed out places that have been lost to the open water. The Gulf has eaten away at the land here, taking with it ridges, forests and old fishing villages. It is common to see pilings where a building or pier once stood in the marsh.

The most pressing threat right now for Plaquemines is what's happened to the marshes since the April 20 BP oil spill. The parish was the hardest-hit area because the Deepwater Horizon exploded about 50 miles away from the parish's tip, where the Mississippi River empties into the Gulf.

The worst of the spill can be found in Bay Jimmy, where the edge of the marsh is black with oil and dying.

Parish officials are frustrated by the federal government's decision to leave damaged marsh like Bay Jimmy alone for fear of doing more damage by trying to clean it up. They say vital marsh is being lost because the oil is not being cleaned up.

“You can see that oil keeps being brought in closer and closer to the marsh,” said P.J. Hahn, the director of the parish's coastal zone management program. He kneeled down and grabbed a handful of tarry, smelly brown oil in his gloved hand. The gooey stuff dropped from his hand.

“You see the oil on top of this thing, it's killed the root system, and slowly the earth is being removed,” he said. “These marshes are very sensitive; there is a lot of life that forms and begins in these marsh areas.”

After the catastrophes of the BP oil spill and Hurricane Katrina, the Gulf Coast hopes that the nation now understands its importance.

Forums to discuss making the Gulf Coast “resilient” will be held in Plaquemines Parish, Lake Charles, Houston, Biloxi, Galveston, Mobile, Ala., Orange Beach, Ala., St. Mary Parish and New Orleans between March and July 2012.

This work follows on a recent $4.5 million risk analysis by Entergy Corp. that found the Gulf Coast faces $350 billion in damage over the next 20 years unless steps are taken to offset natural processes well under way.

The analysis includes vulnerabilities to the offshore oil and gas industry, an economic linchpin for the central and western Gulf.

New Orleans-based Entergy is one of the nation's largest nuclear power providers and an advocate of expanding nuclear power as an alternative to fossil fuels that generate greenhouse gases.

Its study focused on climate change, hurricanes and subsidence, the gradual sinking of coastal lands, a phenomenon particularly bad in Louisiana.

Since at least the 1930s, the Mississippi River delta has been eroding. Chief culprits include levee construction, oil drilling and hurricane storm surge.

Louisiana has lost about 2,100 square miles of coast and loses about 25 square miles a year, according to the U.S. Geological Survey.

On average, the Gulf region suffers losses of about $14 billion a year, the Entergy study found. But over the next 20 years, losses are expected to rise to between $18 billion and $23 billion a year.

Of course, losses could be averted by spending tens of billions of dollars to prepare for future hazards, the study said.

The Gulf Coast communities are being asked to look at how they might adapt. They could adopt tougher building codes, build better levees, restore wetlands and beaches and change practices in offshore drilling, such as higher standards for offshore platforms and replacing semi-submersible drilling rigs with drill ships, and strengthening electric utility systems.