Updated

A $50 billion, 50-year proposal aspires to stop coastal land loss in Louisiana, build new levee systems to protect cities and even begin to slowly reverse the trend of eroding marsh that has turned the entire southern portion of the state into one of the nation's most vulnerable regions to sea level rise.

On Thursday, Gov. Bobby Jindal's coastal team said it would like to spend billions of dollars the state expects to get over the next half-century from increased royalties from offshore drilling, fines from the BP PLC oil spill and other sources to try to save the coast. The idea is garnering praise from some scientists and skepticism from others who openly wonder if the coast should be saved.

Since the 1930s, the state's coast has lost about 1,900 square miles, an area larger than Rhode Island. Louisiana's delta, created by the Mississippi River, has been falling apart because of levees on the Mississippi, oil drilling and other causes.

Since the 1990s, the federal and state governments have spent hundreds of millions of dollars on coastal restoration, but those efforts have been unable to stop land loss and the White House has backed plans for a much more aggressive program to save coastal Louisiana from disappearing.

"Our choice is simple: embrace a robust suite of solutions that address our crisis head on, or give up on the coast," the plan says.

Optimistically, the plan if carried out foresees an end to land loss in 30 years and creating up to 859 square miles of land over the next five decades. If nothing is done to stem the rising seas and land loss, the plan predicts the state would lose 1,756 square miles over that time.

Much of that new land, the plan says, would be built by opening up diversions on the Mississippi River and the Atchafalaya River to flush sediment and freshwater into marshlands now sinking and eroding. Also, it calls for building new ridges, pumping sediment into eroded marshes, building new shorelines, shoring up coastal spots that have fallen apart and pouring sand onto disappearing barrier islands.

Significantly, the plan also calls for new levee systems for the coastal cities and towns, including better protection for New Orleans and new levees for Lake Charles, Houma, Slidell, Morgan City, New Iberia and Abbeville.

"The state of Louisiana has tackled this world-class problem with a world-class approach," said William Dennison, a marine scientist with the University of Maryland's Center for Environmental Science who helped craft the report. "They are making a strong case that this is not just a Louisiana issue, but it is a national issue."

He praised the plan for making "hard choices" about where to focus efforts.

"There are difficult trade-offs," he said. "There are going to be some winners and losers."

Still, there was something in the plan for nearly every location along the coast — and that will surely leave many scientists and critics questioning how realistic the proposal is and stir debate about whether many parts of southern Louisiana can be saved from the rising Gulf of Mexico.

Edward P. Richards is a science and public health law professor at Louisiana State University studying the state's coastal policies. He said any plan that proposes to save most of coastal Louisiana puts people in harm's way. The government encouraging people to continue living along the coast will result in new disasters when the next major hurricane strikes, he contends.

"We have threats that are so politically unpalatable to deal with that we create mythologies to reassure the public that we are properly managing those threats," he said. "What should be seriously debated is whether there should be any levees built anywhere or whether we should let the coast naturally shrink and move inland."

No communities are left behind under the plan, said Garret Graves, chairman of the Coastal Protection and Restoration Authority, the agency that developed the idea.

He said the plan had a "degree of realism" that previous plans for saving the coast lacked. He said the idea to use computer models to prioritize projects takes out the political element that went into determining what got done. Often, those "who screamed the loudest" were rewarded with projects.

He said the new plan was "unassailable in terms of science."

Still, some scientists remained guarded.

Robert S. Young, a coastal geologist at Western Carolina University who studies Louisiana's problems, said the plan amounted to re-engineering the coast, which would create new problems.

"They are changing the topography of coastal Louisiana," Young said. "I'm a firm believer that we are not smart enough to know what that will do when the next Hurricane Katrina sweeps across coastal Louisiana."

He also questioned the optimistic estimates about land creation.

"Are they creating any land that has any value, either from an ecosystem perspective or a storm protection perspective?"

But he praised the blueprint for its apparent candidness. "There is finally a recognition that they will not be able to protect the entire map of Louisiana as it exists now or as it existed in the 20th century."

The public will have a chance to comment on it before it is presented to the Louisiana Legislature in March.

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On The Web:

Louisiana's new coastal master plan: http://www.coastalmasterplan.louisiana.gov/