What's currently left of the marsh along the East Pearl River and the Rigolets, where the 2017 Coastal Master Plan now includes a flood gate to combat storm surge into Lake Pontchartrain. (Photo by David Grunfeld, NOLA.com | The Times-Picayune) ((Photo by David Grunfeld, NOLA.com |The Times-Picayune))
The ambitious 2017 rewrite of Louisiana's $50 billion, 50-year coastal protection and restoration master plan could reduce hurricane storm surge damage by $8.3 billion a year through 2067 and create 800 more square miles of coastal wetlands and dry land than if the plan is not implemented...
Included in it are dozens of fast-track coastal restoration projects, to be built within 10 years, and two major sediment diversions -- Mid-Barataria and Mid-Breton -- that have been under development on the east and west banks of the Mississippi River below Belle Chasse for several years.
Among the major proposed changes since the plan was last revised in 2012:
- Floodgates would be built at the Chef Menteur and Rigolets passes, to keep storm surge from charging into Lake Pontchartrain, and a U-shaped levee would be constructed for Slidell.
- No major levee work would be undertaken to protect the Jean Lafitte area on the West Bank of Jefferson Parish.
- A combination levee and floodwall would be built along U.S. 90 between Raceland and Boutte
- Other new levee projects would be mounted along portions of the central and western Louisiana coast.
The master plan is Louisiana's premier comprehensive blueprint for buttressing the state's retreating coastline and shielding coastal parishes from hurricane damage. The latest version, released Tuesday (Jan. 3), was prepared by the staff of the state's Coastal Protection and Restoration Authority and is online at the authority's website. The authority's governing board will vote on it in the spring, after which the Legislature will pass judgment on it.
Among the 2017 version's other highlights is a new $876.7 million proposal to build a diversion of freshwater from the Mississippi River at Union, just south of the Sunshine Bridge in St. James Parish, during the plan's first 10 years, with the water to be funneled into the West Maurepas swamp near Burnside. This is designed to help restore the cypress tupelo swamp in that area.
The plan also includes an $882.4 million plan to build a sediment diversion near Ama, on the west bank of St. Charles Parish, in years 11 to 30. It would move as much of 50,000 cubic feet per second of sediment and freshwater into the Upper Barataria basin during high river periods.
And it includes a proposal to begin raising portions of east bank New Orleans area levees an average of about 3 feet. That would put them higher than the present standard, which is high enough to prevent topping by surges from a hurricane with a 1 percent chance of occurring in any year, a so-called 100-year storm.
This $2.2 billion project to raise parts of east bank New Orleans area levees is planned for years 31-50 of the plan. They would rise to between 19 and 35 feet above sea level. Levees and floodwalls now in the system range between 16 and 32 feet.
That project would include 38 miles of raised levees and 46 miles of T-walls.
The master plan also includes more than $6 billion dedicated to voluntary "nonstructural" risk reduction projects aimed at floodprone businesses and homes in 36 coastal regions. These projects would floodproof some businesses, elevate a number of homes above base flood levels and buy some homes where flood heights would be more than 14 feet.
The 2017 update continues to stress Louisiana's unique mix of culture and industry based along its verdant wetland coastline, including the area's Cajun history and its reliance on fishing, agriculture and the oil and gas industry.
"Louisiana's coast is certainly not a place that we simply visit and go fishing on the weekends, although we like to do those things," said Bren Haase, head of the Coastal Protection and Restoration Authority's coastal master plan planning team. "It's actually a place where our citizens live and make their living, where they work."
Warming globe, rising seas
The plan also represents a reality check by state officials in that it takes into account updated predictions of rapid increases in sea level rise resulting from human-caused global warming. The sea level rise is expected to rival the Louisiana coastline's already rapid rate of sinking land by 2067: The master plan's lowest estimate of sea level rise, 1.41 feet, is less than the 2012 version's highest estimate.
The moderate sea level height for the 2017 update is 2.07 feet higher water levels by 2067. The high scenario is 2.72 feet above today's water levels.
"The approach we are taking for 2017 is to plan for the worst that we considered," Haase said during a December interview in advance of the plan's release.
"We did a no-regrets scenario," Haase said. "If we plan for that high scenario but we actually get a medium or a low, what does that mean? You do lose a little bit of efficiency (with projects designed for the high scenario), but you're way better than if you plan for a low and end up with a high."
And officials also have scheduled the construction of projects more quickly than called for in previous versions of the plan, in part because of rising concerns about the speed in which coastal wetlands and land are eroding. The plan estimates that a low sea level rise and subsidence scenario will result in 1,200 square miles of lost land, without the projects in the 2017 update. The medium scenario results in 2,200 square miles of land lost, while a high scenario represents 4,100 square miles lost.
"Predictions of sea level rise are not going down," Haase said. "They continue to go up, and one reason we update the plan every five years is to adjust to new science and research."
The advanced construction schedule also recognizes the $10.7 billion that Louisiana estimates will be available during the plan's first 15 years, thanks to money from settlements in the aftermath of the BP Deepwater Horizon oil disaster, and for the state's share of oil and gas revenue from federal offshore waters in the Gulf of Mexico.
State officials already are determining how to borrow money via bonds based on the expected BP and offshore oil money in tyhe first 15 years. The bond proceeds would pay for the fast-track projects.
"This is a long term plan. It's a 50-year plan, but we certainly recognize the need to get some of these benefits on the ground now," Haase said.
Coastal protection projects
The coastal restoration portion of the plan includes 76 projects. Among them are almost $18 billion for using dredged material to create marshes, $5 billion for sediment diversions and more than $2 billion for other projects.
If successful, at the end of 50 years, there will be 800 square miles more of land along the coast than if the plan is not implemented, based on a medium scenario of sea level rise and land subsidence. Under the high scenario, the plan would create or maintain 1,158 square miles, compared to no action. The high scenario assumes more land would be lost if no action is taken.
But officials make clear that even if the plan's restoration projects are successful, the combined effects of erosion, sea level rise spurred by human-caused global warming and subsidence will still claim hundreds of square miles of land along the coast. The plan does not envision a point during its 50 years when the state's restoration program reaches a point of no net loss of wetlands.
If all the projects are completed, they will result in an increase in the amount of suitable habitat available coast wide, compared to today, for important commercial species such as small juvenile white and brown shrimp and oysters and for other species such as adult bay anchovy, spotted seatrout and green-winged teal. But the plan points out that there still will be a reduction in suitable habitat in 50 years resulting from the plan, compared to taking no action.
There's no difference at year 50 for habitat available for blue crabs, juvenile gulf menhaden and gadwall, compared to either current conditions, or not implementing the plan.
Much of the $25 billion earmarked to reduce hurricane storm surge risk is likely to spent over longer periods, with a number of bigger projects proposed after 10 years or after 30 years. That's because of longer design times and a recognition that there are no funding sources identified for most of these projects.
The plan calls for spending $19 billion on a dozen new or improved levee or other structural projects aimed at reducing storm surge damage in coastal communities. These include the re-emergence of several longer levees that are considered controversial or have already been rejected as too costly by the Army Corps of Engineers.
To learn more about how the 2017 update of the Master Plan affects you, visit the Master Plan Data Viewer, which also includes helpful hints on how to make your community safer and more resilient. The plan also includes an appendix of fact sheets for each of its major projects.
The protection side also calls for spending $6 billion in 36 "nonstructural" risk reduction project areas: floodproofing as many as 1,400 business structures, elevating more than 22,500 homes and acquiring as many as 2,400 homes in flood-prone areas across the state.
If successful, the flood risk reduction projects would save an average of more than $8.3 billion a year by 2067 in economic damage, compared to $12.1 billion a year in average damage without adopting the plan. Under the high scenario, adopting the plan would save an average $12.2 billion a year, compared to damage totalling an average $19.9 billion a year without the projects.
The plan concludes that under the medium scenario, successful adoption of its projects would reduce the expected annual damage from storm surge by more than 90 percent in Garyville, Ama, LaPlace, Reserve, Algiers, Hahnville, Luling, Montz, Donaldsonville, Convent and Larose; and more than 75 percent in Slidell, Kenner and Metairie.
Starting with the 2012 plan, state officials reviewed all projects not already under way or funded then considered another 133 restoration, 54 nonstructural and 20 structural projects.
Each project was first reviewed individually for its ability to reduce flood risk and build land, in light of Louisiana's two biggest constraints:
- The limited amount of sediment available from the Mississippi and Atchafalaya rivers and in the nearshore habitat to use as building materials
- How much money was available for construction.
The projects were also reviewed based on their effects on agricultural and traditional fishing communities, on oil and gas and navigation industries and on their ability to provide flood protection, including to historic properties and strategic assets.
As part of an environmental review, individual projects were weighted based on their effects to a variety of key species such as shrimp, blue crab, oysters and crawfish, freshwater and saltwater fisheries in general and waterfowl, brown pelicans and alligators. The weighting also reviewed the sustainability of the land within the project area, use of natural processes, nitrogen uptake capabilities (to see whether they would help or hinder the annual coastal low oxygen dead zone) and the project's operation and maintenance costs.
The individual projects were run through predictive models to assess those capabilities, then compared with other projects to develop a series of alternative project combinations. Those alternatives were then run through the models to identify their cumulative effects, and the final plan was developed using those results.
On the structural risk reduction side, the plan includes several existing and new large levee projects:
- The $8.2 billion, under-construction Morganza to the Gulf levee system, which is expected to include about 98 miles of earthen levee stretching from the Larose-to-Golden Meadow levee south and west around Houma. This system is designed to feature 22 flood gates, 23 environmental water control structures and a lock in the Houma Navigation Canal.
- The $730.4 million West Shore Lake Pontchartrain levee, recently authorized by Congress, with about 17 miles of earthen levee and a mile of T-wall. This project will run from Montz westward through St. John the Baptist Parish and include nonstructural provisions for some properties in St. James Parish and elsewhere.
- The proposed $941 million Upper Barataria risk reduction levee, with about 39 miles of earthen levee and 1 1/2 miles of T-wall between Boutee and Larose. It's scheduled for construction during the first 30 years of the master plan. A smaller Upper Barataria proposal was included in a much broader Army Corps of Engineers study of potential levees for the Larose to Golden Meadow area; the corps considered it too expensive. State officials contend the levee would significantly reduce storm surge damage in parishes to the north and west that would easily outpace its cost.
- Improvements to the existing Larose to Golden Meadow levee system, to raise its levees to between 12 and 21 feet. This would cost $355.5 million and be scheduled for years 1 to 30 of the plan.
- The Morgan City Back Levee project, scheduled for years 31 to 50 of the plan, with almost 7 miles of earthen levee and almost a mile of T-wall built to between 10 and 12 feet above sea level, a swing gate, barge gate and pump station. The cost is estimated at $140.5 million.
- The Franklin and Vicinity levee project, scheduled for years 31 to 50, to raise existing levees to between 12 1/2 feet and 18 feet above sea level from Wax Lake Outlet to the Charenton Canal, and around the Bayou Sale area, for $380.6 million. The project includes 39 miles of levee and a mile and a half of T-wall.
- The Abbeville and Vicinity project would provide new levee protection south of Delcambre, Erath and Abbeville, following Louisiana 330, in years 31 to 50, for about $775.3 million. The project includes over 19 miles of earthen levee, about a half mile of T-wall and a variety of structures to allow flow of water through the levee.
Four public meetings on the master plan and the 2018 annual plan, which outlines the annual budget for master plan projects, will be held in coastal communities in January. Each will include an open house with information available on both documents, from 3:30 p.m. to 5:30 p.m., followed by formal presentations and public hearings from 5:30 p.m. to 7:30 p.m. The meetings are scheduled for:
- Lake Charles -- Jan. 17, the Lake Charles Civic Center, Jean Lafitte Room, 900 Lakeshore Drive
- New Orleans -- Jan. 18, the Port of New Orleans auditorium, 1350 Port of New Orleans Place
- Houma -- Jan. 24, Houma-Terrebonne Civic Center, Pelican Room, 346 Civic Center Blvd.
- Mandeville -- Jan. 25, David C. Treen Instructional Technology Center, Conference Center, 2024 Livingston St.
Comments on the Master Plan can be submitted by email to email@example.com or regular mail to The Coastal Protection and Restoration Authority, P.O. Box 44027, Baton Rouge, LA 70804.
If submitting feedback via email or regular mail, please specify that your comments are regarding the DRAFT 2017 Coastal Master Plan.
Comments also can be submitted online. All comments must be received or postmarked by March 26.
Email the author | Follow on Twitter
on January 03, 2017 at 12:00 AM, updated January 03, 2017 at 9:10 AM
Share This Blog Post: If you would like to share this blog post, go to the original shorter version of this post and look to lower right for the large green Share button. Ask them to sign up too for the Global Warming Blog.