The Mid-Barataria Sediment Diversion has the capability to build and sustain thousands of acres of land that would provide increased storm surge protection to vulnerable communities, provide necessary habitats to sustain a productive estuary for fish, wildlife, and industry, and bring billions in economic benefit to the surrounding parishes. (Louisiana Coastal Protection and Restoration Authority photo)
Gov. John Bel Edwards officially kicked off the construction of Louisiana's most ambitious wetlands restoration effort to date on Aug. 10 at a groundbreaking ceremony near Ironton along the west bank of the Mississippi River.
Decades in the making, the massive $2.92 billion Mid-Barataria Sediment Diversion aims to recreate the river's ancient, natural land-building processes by diverting a portion of the Mississippi's freshwater, sediment and nutrients into the Barataria Basin.
The hope is that the project will rebuild up to 21 square miles of land and sustain as much as 26,000 acres of wetlands in Jefferson and Plaquemines parishes in the next half-century.
The area has been experiencing some of the highest rates of land loss in the world.
"Today will be remembered as a critical turning point for Louisiana's coast," Edwards told an audience that included the Louisiana Coastal Protection and Restoration Authority (CPRA) as well as several federal and state leaders.
"The Mid-Barataria Sediment Diversion will restore and rebuild thousands of acres of coastal land and provide better protection to our most vulnerable communities and critical infrastructure. I'm grateful to CPRA and our federal, state and local partners for their decades-long effort to make this first-of-its-kind project a reality."
The diversion will include a 2-mi.-long channel built along a 1,600-ft. corridor between the river and the Barataria Basin, with a complex structure of gates on the river side and a wide outfall on the basin side, aimed at moving the sediment and water into areas of open water and existing wetlands when it is completed in about five years, according to the New Orleans Times-Picayune.
Bren Haase, chairman of the CRPA, told the newspaper that the project "could build anywhere from about 20 to 40 square miles within this space. And what we know is while that may not sound like a lot in the grand scheme of things, in terms of what's in the basin, at the end of 50 years or so, that actually represents about 20 percent of the coastal wetlands remaining within this basin, so it's a pretty significant contribution to those wetlands."
Louisiana first requested permits for the project in 2016, but its origin actually stretches back to the end of the 19th century, he said, when scientists at that time raised concerns about levees along the Mississippi River cutting off the supply of sediment that built the state's coastal wetlands.
It was not until 1998 that proposals for diversions similar to Mid-Barataria were included in state plans and in its first coastal Master Plan in 2007.
The new effort calls for the diversion to operate at times between December and June when the water flow is at 450,000 cu. ft. per second (cfs) or greater and designed to allow a maximum flow of 75,000 cfs to enter the basin, likely only during high-river years when the river's flow reaches one million cfs or more.
During low periods, as much as 5,000 cfs will still flow through the channel to keep it clear of sediment.
The Mid-Barataria Sediment Diversion is the state's largest effort to date to reduce the effects of subsidence, sea level rise and tropical storm and hurricane damage, which together have led to the loss of more than 2,000 sq. mi. of the Louisiana's coastline since the 1930s.
Construction is anticipated to take more than five years to complete and is projected to produce an economic impact of nearly $1.5 billion in sales and approximately 12,400 jobs in the region, according to recent economic studies.
Site Preparation Activities Began in June
The Times Picayune reported that Entergy started relocating utility poles and other equipment earlier this summer, and a temporary rerouting of Louisiana Highway 23 will be built this fall, along with the beginning of construction of a permanent bridge replacement across the diversion. Additionally, crews will build a new railroad bridge atop the diversion site in the next few months.
In June, surveying began to identify flooding risks to buildings outside the levee system south of the diversion. The results will be used in discussions with residents and businesses of possible mitigation projects during the last quarter of this year and the first quarter of 2024.
Some projects aimed at elevating roadways and bulkheads between Myrtle Grove and Happy Jack are already under way as well, CPRA officials told the New Orleans news source.
The state has set aside $360 million of the project's construction cost for projects aimed at mitigating the impacts on existing commercial fisheries, and to deal with potential flooding concerns of residents and businesses that are outside hurricane levees south of the diversion.
The extensive project is being built under a state-allowed "construction manager at risk" program, which requires the construction management firms to deliver the project within a guaranteed maximum price, working with designers throughout the design process.
Alberici, based in St. Louis, Mo., and Atlanta's Archer Western, a subsidiary of Walsh Construction, was selected to be the lead construction management companies on the Mid-Barataria diversion effort. There also are 16 subcontractor firms involved in the construction project.
AECOM, which has its headquarters in Dallas, is the enterprise's lead design studio, with assistance from 15 subcontractors. AECOM also serves as the lead construction services contractor with 19 subcontractors working for it.
Last December, the U.S. Army Corps of Engineers (USACE) approved permits and permissions for the Mid-Barataria Sediment Diversion after completing an extensive environmental review and analysis of the project, according to the governor's office.
The multi-billion-dollar construction cost for the diversion includes $2.26 billion provided by federal and state trustees overseeing the BP Deepwater Horizon oil spill damage settlement, and $660 million from the National Fish and Wildlife Foundation, with the funds coming from criminal fines assessed to BP and Transocean.
Many State Officials, Scientists Believe in Diversion's Benefits
The sediment diversion project is not without its critics, among them oyster growers, shrimpers, and other fishers whose catches are likely to be dramatically affected by the diversion's freshwater flow, and a number of politicians, including Lieutenant Gov. Billy Nungesser, who has said the money for the project would be better spent on other projects that build land more quickly.
Other state officials, including Edwards, point to broad support for the project from a variety of scientists and scientific studies, including the environmental impact statement. They have generally concluded the diversion's benefits will outweigh its effects, and they also point out that Louisiana already is spending much of its coastal restoration money on projects that dredge sediment from the river and pump it into open water to build new lands.
They also assert that the diversion's continued flow of sediment and nutrients will extend the life of such pump-and-fill projects beyond their expected 20-year lifetimes. In addition, the land built by the project is expected to reduce storm surge on nearby hurricane levees by as much as 6 in.
Haase, for one, told the Times-Picayune that the diversion will improve freshwater fisheries over its lifetime.
Another expected upside to the Mississippi River's freshwater being used to build new wetlands and improve existing wetlands is that nutrients in the water, including phosphorus and nitrogen, are likely to be taken up by that vegetation before reaching the Gulf of Mexico, he said.
That could help reduce the size of the annual low-oxygen dead zone along the state's coast, which is caused when the nutrients create algae blooms that die and sink to the bottom, where they decompose and use up oxygen in the coastal bottom waters.
The state also will focus part of its mitigation funds on reducing the loss of wetlands in the part of the southernmost wetlands at the river's mouth, which are expected to shrink because the diversion will capture sediment keeping them above water. One way of doing it is creating more crevasses along channels running through existing delta to encourage the building of more land.
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