Landry Administration Writes Off Barataria Basin While Offering New Justification for Cancellation of the Mid-Barataria Diversion

05.04.2026 | In Sediment Diversions

By Lauren Bourg, Director, Mississippi River Delta Program, National Audubon Society &
Alisha Renfro, Coastal Scientist, Mississippi River Delta Restoration Program, National Wildlife Federation

In July of 2025, the Landry Administration canceled the Mid Barataria Sediment Diversion (MBSD), a cornerstone of the state’s Coastal Master Plan since 2007. The state offered various excuses for the decision to legislators in committee last year, including concerns about project costs (despite funding being fully covered by Deepwater Horizon oil spill funds), potential hypoxic conditions in the Barataria Basin, anticipated harm to the oyster industry that would destroy the culture of south Louisiana, and myriad other disproven reasons.

Now, as Louisiana’s legislative session is back in full swing, so is the Landry Administration’s shifting rationale on MBSD. Although the project was no longer funded in the FY27 Annual Plan, Governor Landry sent a letter to the Legislature on April 13, 2026, offering new justifications for cancelling it.

Landry’s letter made bold — and factually incorrect — assertions, including: The diversion would have threatened the drinking water supply for hundreds of thousands of Louisianians and, that the project never would have produced the desired benefits because of lower amounts of sediment in the river.

Governor Landry goes as far to say “the Barataria Basin will likely convert to open water by around 2070 regardless of the diversion.” If true, that claim would be alarming. It would not only undermine the case for the MBSD but also call into question the effectiveness of other coastal restoration efforts currently being pursued by the state, including marsh creation, land bridges, smaller diversions and barrier island projects. It would also raise serious concerns about the long-term viability of levee systems in the Barataria Basin, and, more broadly, about the state’s entire coastal protection and restoration strategy.

However, an extensive evaluation of MBSD’s benefits and potential negative impacts conducted during the project’s permitting process revealed that neither of the Governor’s claims is supported by evidence.

So, what should we take from this latest letter? Rather than strengthening the case for canceling the project, these new arguments are easily challenged, undermining the credibility of the Administration’s earlier claims. Instead of reinforcing their decision to cancel, the letter raises further questions about the role of data, science, and expertise in shaping the state’s coastal policy.

Here are the key facts that address the Governor’s most recent claims:

1. Claim: MBSD would have endangered the drinking water supply.

This claim completely overlooks how the project was designed to work. The diversion is a controlled, gated structure that would only operate under specific river conditions – specifically during periods of high river flow.

Saltwater intrusion becomes a drinking water concern during low river flow. Because the diversion would only operate when the river is high, it would not have been open during the conditions when saltwater intrusion is a risk.

In addition, the structure included safeguards. If unexpected conditions arose while the diversion was open, the gates could be closed. As outlined in the project design, the diversion would shut down if water levels between the Mississippi River and the basin created a risk of reverse flow.

In short, the system was designed to avoid impacts on drinking water, with built-in controls to respond to changing conditions.

2. Claim: The Mississippi River sediment load is collapsing, down 70% since 1850 and on track for a 70-90% decline by 2100.

A tremendous amount of sediment is flowing down the Mississippi River. This sedimentation is visible in the Atchafalaya River Basin where it has created a new delta at the Wax River Outlet and freely creates new habitat along other natural breaks further down the Mississippi’s main stem. In fact, there is so much sediment in the Mississippi River and other federal channels in Louisiana that the U.S. Army Corps of Engineers, New Orleans district, dredges an average of 77 million cubic yards of sediment each year, making it the largest channel operations and maintenance program in the nation. Right now, that sediment is seldom used for restoration purposes.

The Corps has a beneficial use program that has used that sediment to create around 29,000 acres of wetlands in and around the Birds Foot Delta, and the state restores wetlands by dredging sediment from the river bottom and pumping it to nearby marshes.
MBSD was designed to do this more efficiently and more naturally. It would have captured both the heavier, land-building sands from the river bottom and the finer silt and clay carried in the water, moving them into wetlands during high river flows, similar to how the river once functioned before being leveed, and the delta was built.

Even accounting for changes in sediment levels, the project’s environmental review found that MBSD would still deliver significant benefits, compared to alternatives such as large-scale marsh creation. It was projected to build:

After 50 years, that would represent about 20% of the remaining marsh in the Barataria Basin – outperforming smaller diversion projects and large-scale dredging alone, while also restoring a more natural connection between the river and surrounding wetlands.

There’s also a key contradiction in the Governor’s argument. The state’s current plans for the Barataria Basin still rely on sediment from the Mississippi River – either by dredging it to build land bridges or by constructing a smaller diversion. If the river’s supply were truly collapsing, these strategies wouldn’t work either way.

3. Claim: With the projected two meters of sea level rise, the Barataria Basin will likely convert to open water by around 2070, regardless of the diversion.

This final claim is the most alarming because it misrepresents the science and uses that to justify stepping away from coastal restoration in one of the state’s most important regions.
The Barataria Basin is home to about 370,000 people across nine parishes. It also supports major economic assets, including refineries, petrochemical facilities, grain terminals, the Port of South Louisiana, Port Fourchon, and both commercial and recreational fisheries. Writing it off would have serious economic and environmental consequences.

The basin does face real challenges: ongoing wetland loss from sea level rise and subsidence, along with increasing storm surge associated with it. But these risks have always been the reason for continued investment in protection and restoration, not a reason to abandon those efforts.

It’s also important to put sea level rise projects in context.

In other words, current projections are well below the two-meter figure cited by the Governor. If anything, they suggest that restoration efforts, like rebuilding wetlands, could be more effective than previously thought.

Bottom line: the science does not support writing off the Barataria Basin. For twenty years, Louisiana has relied on science to guide its response to coastal changes and plans for the future. That approach produced four Coastal Master Plans and helped secure $21.5 billion for protection and restoration. The Mid-Barataria Sediment Diversion was the result of that same process; decades of research, years of independent scientific review, and extensive state and federal oversight that addressed the very concerns now being raised.

And yet, despite these extensive efforts, the project is canceled, and the Governor continues to defend that decision with shifting claims that don’t hold up to scrutiny.
The next time the Governor wants to pressure the Legislature, he should stick to politics rather than playing scientist. Misrepresenting the science only undermines the confidence in the state’s coastal program and risks the future of one of Louisiana’s most vital regions.