Posted on March 8, 2021
Mid-Barataria Sediment Diversion could create 28 square miles of marsh in rapidly eroding Barataria Basin
One of the most expensive, ambitious and controversial proposals in Louisiana’s 50-year, $50 billion bid to save the southern third of the state from disappearing like a modern-day Atlantis passed a major milestone Thursday night with the release of a mostly positive assessment from the Army Corps of Engineers.
Four years in the making, the Corps’ draft environmental impact statement found that the benefits of the Mid-Barataria Sediment Diversion – chiefly, creating and sustaining 28 square miles of marshes in the rapidly eroding Barataria Basin – more than outweigh the attendant disruption to oyster, brown shrimp and saltwater fisheries, and to bottlenose dolphins.
And in the report, the Corps redefined the need for the project, from simply restoring the natural input of sediment and freshwater in the basin to also using those resources to heal injuries caused by the 2010 Deepwater Horizon oil disaster. The addition recognizes that the project’s construction price tag, now approaching $2 billion, will be fully funded from the $8 billion that BP is setting aside to compensate for damages.
The project calls for gouging a wide hole in the Mississippi River levee in lower Plaquemines Parish and filling it with a concrete structure to channel as much as 75,000 cubic feet of sediment-laden river water per second into the West Bank wetlands. Rebuilding those marshes, badly wounded over time by hurricanes, oil and gas work and the loss of replenishing sediment since the wandering river was leveed more than a century ago, would reduce the height of storm surge across some West Bank communities by as much as one foot, the report concluded.
The financial costs are pegged at $1.5 billion to build the diversion structures, plus at least $305 million to make up for permanent damage to wildlife and nearby communities, according to state Coastal Protection and Restoration Authority officials. Another $81 million in criminal fine money from the BP spill was used in designing the project.
Louisiana officials say it’s well worth the risks.
“It is our belief that the Mid-Barataria Sediment Diversion is the lifeline that our coast needs, it is the shot in the arm that the Barataria Basin needs and it is the only real and sustainable way to build tens of thousands of acres of marsh,” authority chairman Chip Kline said. “It will help protect the overwhelming majority of the citizens in southeast Louisiana, it will help preserve our working coast that we know we have here in south Louisiana and it will undoubtedly help preserve the cultural heritage that exists in southeast Louisiana.”
The document also was praised by U.S. Rep. Garret Graves, R-Baton Rouge, the coastal authority’s former chairman.
“You will never have a sustainable footprint of south Louisiana without fundamental changes to how the Corps of Engineers manages the river system and its sediment by reconnecting some of the distribution channels that used to exist and reestablishing access to fresh water, sediment and nutrients for the adjacent wetlands,” Graves said. “This project represents that kind of fundamental change and puts the basin on a path to a sustainable future.”
Work on the long-awaited environmental statement began in 2017, a year after the state began the process of securing federal permits to build it. But the idea of a diversion, to replace sediment that is now blocked from entering Barataria Basin during spring floods by the expansion of Mississippi River levees for flood protection and widening of the river’s channel, actually dates from the late 19th century.
It’s controversial among fishers who rely on shrimp, oysters and finfish that are now harvested in the existing mix of fresh to salt water in the long basin between Jean Lafitte and Grand Isle. They contend that freshening the basin with river water will kill their livelihoods and dilute region’s rich culture.
But the new report supports arguments by state officials that the continued loss of wetlands in the basin cannot be overcome by repeated construction of smaller projects, in which sediment is mined by dredges inside the Mississippi riverbed and piped miles inland to fill open water areas. While the state is still actually spending more money on these types of projects, studies indicate half of all dredged material put in the basin would be lost by the end of project’s 50 year lifetime, and the loss rates increase in the last three decades because created marsh can’t keep up with sea level rise.
The report also dismissed an alternative of building multiple small-scale diversions that would flow at between 5,000 and 10,000 cubic feet per second because the multiple projects would be too expensive and wouldn’t deliver enough coarse sediment grains to be effective.
A major benefit of the diversion is that wetlands created by it will reduce hurricane storm surge heights, adding protection to West Bank communities, including a significant population of Black and low-income residents, the study found.
And while expected rises in sea level during the later part of the project’s first 50 years will reduce the land created and nourished by the diversion to about 21 square miles, the 20% of Barataria Basin wetlands it protects will be much larger than what would be were no diversion was built, according to the study.
Public input sought
The 5,800-page environmental impact statement and appendices were produced by a team of scientists and engineers from the Corps, other federal agencies and the state. Its release is part of the federal permitting process under the Clean Water Act, Rivers and Harbors Act and National Environmental Policy Act. It can be viewed online: https://www.mvn.usace.army.mil/Missions/Regulatory/Permits/Mid-Barataria-Sediment-Diversion-EIS/
After a 60-day public comment period ending May 4, a final version of the statement will be released, with the permit process expected to be completed in April 2022. Comments may be submitted electronically at https://parkplanning.nps.gov/MBSD; by calling (866) 211-9205; or by mail to U.S. Army Corps of Engineers, New Orleans District; Attn: CEMVN-ODR-E, MVN-2012-2806-EOO; 7400 Leake Ave.; New Orleans 70118.
Release of the environmental assessment was accompanied by a draft restoration plan by the Louisiana Trustees Implementation Group. That panel of representatives of federal and state agencies oversees natural resource damage assessment projects that are funded by $8 billion paid by BP for its 2010 Deepwater Horizon oil disaster in the Gulf of Mexico. About 95% of the disaster’s marsh oiling occurred in coastal Louisiana, with the heaviest and most persistent oiling in the Barataria Basin – doubling or tripling the rate of marsh erosion.
Kline urged residents to take advantage of the comment period. The Corps and the trustees group will jointly host three virtual meetings to receive public comment on the statement and the draft restoration plan. Attendees may participate online by WebEx or by telephone. The meetings are scheduled April 6 at 9 a.m., April 7 at 1 p.m. and April 8 at 6 p.m. Information on how to join by computer or phone will be posted on the corps website about two weeks before the meetings. Copies of the assessment also are available at that website.
“This is a real opportunity for the public to put their concerns on the record, force us as the CPRA and force all the various federal agencies that are in this regulatory process to evaluate their concerns in a real and meaningful way,” he said. “We want the public to take a massive swing at some these mitigation measures – what did we get right, what did we get wrong, what can we do better, what can we do more of,” he said.
The two-mile-long diversion structure would be built at river mile marker 60.7 above Head of Passes, on what is now farmland between the Phillips 66 Alliance Refinery on the north and the communities of Myrtle Grove and Ironton to the south.
The preferred alternative design for the diversion calls for it to begin operating in winter and spring months when the river flow at Belle Chasse exceeds 450,000 cubic feet per second. A maximum 75,000 cfs of river freshwater containing sediment and nutrients would flow into the eastern Barataria Basin when the river flow reaches 1 million cubic feet per second or more, which would occur during years when Midwest floodwaters reach Louisiana.
When the river flow drops below 450,000 cfs, the diversion gates would be closed, but a continuous flow of 5,000 cfs of river water would continue, to keep salinity levels in wetlands closest to the diversion at steady levels.
The flow of freshwater would dramatically reduce salinity levels throughout the basin, cutting the amount of brackish and salt marsh and increasing areas of freshwater marsh.
The freshwater flow also is expected to change the areas where oysters can survive and conventional commercial fish species can be harvested, and will significantly disrupt the brown shrimp life cycle.
To mitigate those effects, the state plans to expand a variety of existing efforts to help fishers who have been hurt by freshwater in recent high-river years.
For oysters, the state plans to establish a new public seed ground in the lower Barataria Basin, provide cultch material for both public and private growing areas, help improve oyster broodstock reefs and fund programs to develop off-bottom oyster farming as an alternative for conventional oyster beds on Barataria Basin waterbottoms.
State officials say the Department of Wildlife and Fisheries already has begun to address some of the oyster concerns in its own new oyster strategy. That includes locating new areas where state-owned water bottoms may be leased to private growers.
Mitigation for shrimp fishers is expected to include financial assistance for improving refrigeration on vessels, so shrimpers can travel farther from their bases to capture larger shrimp. Money also will be made available to fund gear improvements on shrimp boats to increase efficiency.
The mitigation plan also calls for spending $5 million on new marketing for both oyster and shrimp, business training programs and workforce training to help some fishers transition to other industries or to operate where shrimp are likely to be more prevalent.
Benefits seen for other species
The environmental document and the trustees plan also say that more freshwater actually benefits some species important for recreational and commercial fishers, including largemouth bass, red drum, gulf menhaden and bay anchovy. They say negligible to minor benefits will accrue from the freshwater changes for white shrimp and blue crabs.
The freshwater increases are seen to result in minor to moderate benefits to other important south Louisiana species, including alligators and green-winged teal and mottled ducks.
Other recreational use benefits include duck hunting and bird watching. The addition of sediment to the basin also will mean more submerged aquatic vegetation and will help increase areas of more shallow water bottoms.
The added wetlands and also will help the Gulf through the transfer of energy – food in the form of plants that decay along marsh edges – and through the addition of nutrients to the Gulf waters.
The diversion could kill or chase off as much as 30% of the existing bottlenose dolphins in the basin. But the state says it will expand a monitoring system aimed at measuring the effects of the diversion on dolphins and other wildlife, and will try to minimize the effects of low salinity on dolphins where possible.
That includes money to reduce other threats to dolphins: fishing gear, illegal feeding, noise issues and human predators.
The state also says it will increase the size and funding through 2046 for a new statewide stranding network aimed at responding whenever a dolphin beaches or is otherwise identified as ill in the basin. And the state says it will create a new contingency fund to address “unusual mortality event” declarations in the basin, which occur when strandings and die-offs occur.
Help for nearby residents
Other mitigation efforts include money to help residents in six nearby communities with possible increased water levels. When operating, water heights will be about a foot greater at the diversion’s outfall, and drop off with distance. While the diversion is likely to raise water levels in its first 50 years, sea level rise and subsidence in those communities will outstrip its effects beyond that time.
The state has identified about 530 properties, in Myrtle Grove, Woodpark, Suzie Bayou, Hermitage and Grand Bayou below the diversion site, that are not protected by levees. Only about a quarter of those properties were subject to homestead exemption, so many are likely vacation camps.
But some, like the Grand Bayou community of Native Americans, include low-income and minority populations.
Construction of the diversion could also adversely affect the minority and low-income residents of Ironton, the environmental statement warns. And tidal flooding could increase in the Lafitte area, which has varying levels of low, nonfederal flood protection, the report warned.
To mitigate the diversion’s effects, the state is looking at raising some roads and other community infrastructure. It also will consider paying to raise buildings, improve access and assist in septic tank problems for affected homes.
In some cases, it will ask for the establishment of voluntary easements for the water effects for properties outside levee protection, and will be open to requests by property owners for buyouts.
But just as the water flow from the diversion to the south causes problems, the creation of wetlands in the Barataria Basin is likely to reduce storm surge by as much as one foot in communities outside levees to the north.
The diversion of sediment and water into Barataria Bay will also likely cause moderate, permanent adverse effects on wetlands in the existing birdfoot delta, resulting in a reduction of between 2,000 and 3,000 acres of wetlands by 2070, compared to the no-action alternative to the project. That wetland reduction would especially affect the Delta National Wildlife Refuge and the state’s Pass-a-Loutre Wildlife Management Area. The report does not discuss how that loss would be affected in the future by the Corps practice of moving sediment dredged to deepen the lower river to 50 feet, and expected future maintenance dredging, into those two areas.
State officials also said the public should not view the diversion as just a stand-alone project. Major projects building new wetlands using sediment dredged from the river and pumped inland are already underway in the Spanish Pass area just south of the diversion location, and a new project will begin construction later this year on expanding wetlands built with an earlier pipeline project just north of the diversion.
The coastal authority’s executive director, Bren Haase, said there likely also will be opportunities to use sediment captured by the Corps during maintenance dredging of the river channel to build wetlands near the diversion’s outfall. As wetlands in the outfall area expand, dredges will be used to keep channels open to allow new sediment and water to move farther out into open water areas.
