Louisiana coastal restoration 50-year blueprint released

01 12, 2012 by The Times-Picayune

Declaring Louisiana’s loss of coastal wetlands “nothing short of a national emergency,” state officials today released a $50 billion, 50-year strategy for rebuilding land and increasing protection from storm surge for coastal communities that they say can be paid for with money the state is reasonably sure it will receive.

The strategy is outlined in the Coastal Protection and Restoration Authority’s draft five-year master plan update, which for the first time contains maps showing the location and scope of proposed projects and maps showing what the state’s coastline will look like in 2061 if they’re built. Lists of the projects also show their cost.

The master plan will be available on the Web today at noon at www.coastalmasterplan.la.gov.

Also included is a map showing the wetlands loss that will occur by 2061 if the master plan isn’t implemented and the extent of flooding from storm surges that will accompany a 100-year hurricane in 2061 if the projects aren’t built.

The document makes clear that some smaller coastal communities, and some segments of rapidly eroding coastal wetlands, will be losers in the expensive race to restoration.

The state has lost 1,883 square miles of land during the past 80 years, an area three-quarters the size of Delaware, and authority Chairman Garret Graves said it is impossible to return the state’s coastline to its 1930s condition. Even having a coastline in 2061 that resembles the current one might be impossible, he said.

But if the projects outlined in the plan work, Louisiana would see more land gained than lost by 2042, with that gain averaging about 2.5 square miles a year by 2061. By then, the projects would have built 859 square miles of new land, although much of the gain will be offset by erosion elsewhere.

“We put together realistic parameters here,” Graves said.

‘Moderate’ take on future

The $50 billion the plan requires over 50 years includes a share of fines from the 2010 Deepwater Horizon oil spill, congressional appropriations for levee and restoration programs, and a share of federal offshore oil money that will increase to about $200 million a year in 2017.

Improved levee protection and strategically placed restoration projects will decrease by $5.4 billion the average annual damage caused by flooding from storms after 2061, Graves said — though he estimates there will still be an average of $2.3 billion in damage.

The report emphasizes that even with the additional improvements, people living along the coast will still face risk from flooding.

The damage estimate is based on a “moderate” view of future land loss, adopting midrange scenarios for the strength of hurricanes and the rate of sinking soils and sea-level rise.

Those estimates are based on land loss rates ranging from 15 square miles to 51 square miles a year. The less-optimistic scenario would result in the loss of 1,756 square miles during the next 50 years, or almost as much land as was lost in the past 70 years.

Though it uses estimates based on the Army Corps of Engineers’ climate change-driven scenarios, the report itself does not include an explanation of climate change, or even use the words “climate change” or “global warming.”

The plan calls for allocating half the $50 billion to risk-reduction projects such as levees, and half to restoration projects.

Varying levels of strength

The master plan includes both 100-year and 500-year levee projects. A 100-year levee protects from surges caused by a hurricane with a 1 percent chance of occurring any year, similar to Hurricane Gustav’s effects in New Orleans in 2008. A 500-year levee protects from surges caused by a hurricane with a 0.2 percent chance of occurring in any year, a bit stronger than Hurricane Katrina as it went ashore in Mississippi.

Restoration measures will include the use of sediment and water from the Mississippi and Atchafalaya rivers to maintain and rebuild land, including cypress swamps, marshes, ridges and barrier islands. Projects will include diversions that would pump as much as 250,000 cubic feet per second of sediment and water during high-river events, and much smaller amounts at other times. The sediment would build and maintain wetlands.

Other projects will pump dredged sediment through pipelines to rapidly build land bridges and wetlands that would then be maintained with diversions. Similar methods would be used to build and maintain barrier islands and beaches.

New 100-year levees would be built during the next 20 years to protect Slidell and LaPlace. The Slidell levee system would cost $72 million, while extending the existing lakefront levees to LaPlace would cost $469 million. The levee at Alliance in Plaquemines Parish also would be upgraded to 100-year protection, for $510 million.

To the west, the proposed, 72-mile Morganza to the Gulf levee surrounding Houma would be built to 100-year standards, for $4 billion. The 100-year Larose to Golden Meadow levee would cost $258 million.

A new 100-year levee also would be built to protect communities in Iberia and Vermilion parishes, for $1.6 billion.

Major N.O. area upgrade

Between 2031 and 2061, the recently completed 100-year New Orleans area levee system would be upgraded to provide 500-year protection for $1.8 billion. A 100-year ring levee would be built at about the same time around the Lafitte area, for $856 million. A 500-year ring levee around Lake Charles also would be built, costing $1.1 billion.

The report says $12.9 billion will be spent on “nonstructural measures,” including raising residential and commercial properties, “floodproofing” homes and businesses, and buying homes in the most at-risk areas. State officials say they expect only 70 percent to 80 percent of those eligible to participate, and they will continue to recommend that participation be voluntary.

Those measures would be available to communities like Isle de Jean Charles, a village in Lafourche Parish largely populated by members of the United Houma Nations. The Army Corps of Engineers, in approving that Morganza to the Gulf levee system, determined it was not cost-effective to extend it to include the village.

“Could you take $300 million to protect Isle de Jean Charles or some other smaller community? Yes, you could do that,” Graves said. “But what that means is a trade-off for maybe the 500-year level of protection for New Orleans, where you get the best bang for the buck.”

While it’s still unclear how the “nonstructural” projects would be paid for, state officials said state money would be used where necessary to elevate homes to levels required by the National Flood Insurance Program, which could be as much as 14 to 17 feet above sea level.

Parishes will be asked to incorporate nonstructural requirements in zoning ordinances and building codes, and the state also will be lobbying federal agencies, including FEMA and the Department of Housing and Urban Development, for financial assistance.

Investment in marshes

The biggest chunk of money set aside for restoration, $17.9 billion, will be spent on marsh creation.

In the New Orleans area, the biggest of these projects during the plan’s first 20 years will be the creation of 8,513 acres of marsh in the eastern New Orleans landbridge, which divides Lake Borgne from Lake Pontchartrain, for $2.448 billion.

A similar project creates 5,378 acres of marsh to the west of Myrtle Grove in the Barataria Basin for $1.7 billion.

Another $304 million will create 2,443 acres of marsh in the Golden Triangle area, sandwiched between the Gulf Intracoastal Waterway, the Mississippi River-Gulf Outlet and the northwestern edge of Lake Borgne.

In the plan’s last 30 years, the biggest project is the creation of 15,972 acres of wetlands in the Biloxi Marsh adjacent to Delacroix, for $1.6 billion. Another 2,009 acres of marsh will be built along the northern rim of Barataria Bay for $223 million.

While only $4.3 billion is set aside for diversions, they’re likely to be the most controversial projects in the master plan. There will be seven diversions along the Mississippi River, with all but one operating only during moderate to high river flows.

For instance, a $219 million diversion into upper Breton Sound on the east side of the river near Braithwaite would capture 8 percent of the river’s flow when it rises above 200,000 cubic feet per second, increasing with the flow. During high river events, the diversion would pump 250,000 cubic feet per second into the sound, about as much water as the Bonnet Carre Spillway is designed to move into Lake Pontchartrain during emergencies.

A diversion into lower Breton Sound would operate with a maximum of 50,000 cubic feet per second under a similar stepped scale.

On the western side of the river, similarly sized diversions would pump water into Barataria Bay at Myrtle Grove and at Empire.

In the southeastern region, the plan also includes $845 million for rebuilding barrier islands and headlands along the coast from just south of Port Fourchon in Lafourche Parish to Sandy Point, just west of Venice.

Residents’ voices to be heard

The public is being asked to comment on the draft plan through Feb. 25.

The restoration authority will hold three public meetings across the state. Each begins with an open house at 1 p.m., followed by a public hearing from 5:30 p.m. to 7:30: p.m.:

  • Jan. 23, New Orleans, at the Lindy Boggs Conference Center Auditorium on the University of New Orleans campus.
  • Jan. 24, Houma-Terrebonne Civic Center
  • Jan. 25, Lake Charles Civic Center.