Louisiana’s Greatest Diversion

August 28, 2023by Andrew Wilson0

On August 10, 2023, the State, including Governor John Bel Edwards, Louisiana’s Coastal Protection & Restoration Authority (“CPRA”), and other State officials, broke ground for the construction of the Mid-Barataria Diversion Structure, the largest individual coastal restoration project the State has ever built. The Project will be located on the west bank of the Lower Mississippi River at MM 61in Plaquemines Parish near Ironton, LA, and will cost $2.9 billion.

Projects in Construction- 2012 April- 2.5
Solid brown area indicates 21,000- 26,000 acre land area to be created by Diversion. (CPRA Image)

The Project is intended to recreate as much as 20 to 40 square miles (26,000 acres) of land over some 50 years. It will recreate or mimic the historical function of the Mississippi River which, for tens of thousands of years, “flopped about like a garden hose” as Tulane Law Professor Oliver Houck has put it, depositing rich, nutrient-laden sediment and creating huge lobes of land to form what is now all of southeast Louisiana.

Project is intended to recreate
(LDNR image)

Sadly, when the Mississippi River Levee system was constructed after the 1927 Flood to stop flooding of nearby communities, the River could no longer deposit sediment and the land building process ended for the most part. Without new sediment, the coastline began to erode, a process which was accelerated by the network of pipeline and oil & gas canals which eventually crisscrossed the coast and served as capillaries to absorb saltwater from the Gulf and kill freshwater plants and habitat. As a result, the State has lost an area the size of Connecticut since the levee system was built, and continues to lose an area the size of a football field every 100 minutes.

The Mid Barataria Sediment Diversion is just one of several coastal projects the State has built to slow or stop this erosion process. Others include bank stabilization, barrier Island/headland restoration, hydrologic restoration, living shoreline (artificial, bioengineered oyster reefs), marsh creation and ridge restoration (using dredging), shoreline protection (near-shore rock breakwaters to reduce wave energies on shorelines), and freshwater diversions.

The Project consists of a series of gates that can be raised and lowered to increase or decrease the flow generated by the hydrostatic pressure from the River which flows at an average rate of 450,000 cubic feet per second. The Project’s designed flow will be roughly 15% of that or 75,000 cfs, and will carry river water laden with sediment down a canal to Barataria Bay. There sediment will be deposited as the flow decreases. The Project is being constructed in the bend of the river where the river slows and sediment accumulates so as to enhance the efficiency of the project.

Graphic of Mid-Barataria Diversion Structure
Graphic of Mid-Barataria Diversion Structure components. (CPRA Image)

The Project is not without its opposition. Given the enormous amount of freshwater which will be introduced to Barataria Bay with the sediment, commercial fishermen are concerned about adverse impacts on fisheries, particularly shrimp and oysters. Brackish wetlands currently serve as “nurseries” for many species of fish as well as shrimp. And oysters cannot survive if salinity is reduced to less than 5 parts per thousand (ppt) for extended periods of time. The Environmental Impact Statement (EIS) for the Project expressly states that these fisheries will experience significant impacts. Given the extensive numbers of oyster leases in Barataria Bay, oyster fishermen will expect compensation for their losses.

Previously in 1991, to stop saltwater intrusion the State built the Caernarvon Freshwater Diversion Structure on the east bank of the River to reintroduce freshwater from the River at the head of Breton Bay/Sound. In 2002, the State opened the Davis Pond Diversion Structure on the west bank of the Mississippi River to reintroduce freshwater at the head of Barataria Bay. The freshwater outfall areas for both projects contained thousands of acres of oyster leases. Target concentrations of salinity (isohalines) were established by governmental entities for each project in an effort to restore the historical salinity levels which State officials claimed would ultimately benefit the oyster industry. But the oyster industry disagreed and demanded compensation.

LDNR image
(LDNR image)

For the Caernarvon diversion, no compensation was offered to oyster leaseholders, so they sued. The litigation went on for some 15 years bringing many coastal restoration projects to a halt. Ultimately the Louisiana Supreme Court threw out the oyster fishermen’s claims for billions of dollars. (Avenal v. State, 886 So.2d 1085 (2004). In contrast, for the Davis Pond Diversion, the State offered compensation to those leases in the likely impact area based upon a compensation formula and no litigation occurred. But these projects flow at a maximum designed rate less than 10% of the projected flow of this Mid-Barataria Project.

State officials advise that $400,000,000 has been set aside for “mitigation” of the adverse effects of the Mid-Barataria Project. Questions are now arising as to how these funds would be spent and whether it will be enough. The jury is still out….

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