Myths Busted - Mid-Barataria Will Help, Not Hurt, Coastal Louisiana

There’s been a lot of talk about the effects the Mid-Barataria Sediment Diversion. This project is a cornerstone of Louisiana’s Coastal Master Plan and will build and maintain 30,000 acres over 50 years by reconnecting the Mississippi River to its wetlands.

Despite the scientific evidence and research, there are claims that the proposed sediment diversion should not be built. Some critics cite “scientific” studies that they say back-up their positions. But If you analyze these claims, you find that the facts don’t add up.

Dr. Alisha Renfro, a scientist with Restore the Mississippi Delta, refutes concerns and explains point-by-point the real facts about sediment diversions and why they are crucial to rebuilding coastal Louisiana.

Diversions build land. Period. The claim that diversions will cause, not curb, land loss is a result of the land loss experienced in the Breton Basin following Hurricane Katrina, including the area around the Caernarvon Freshwater Diversion.

While not a Sediment Diversion, the Caernarvon Freshwater Diversion builds land. Since 1991, the freshwater diversion has built 700 acres of new land, despite not being intended or implemented for that purpose. Mid-Barataria will carry sediment at a larger scale and is designed to recreate lost areas.

Wetlands need sediment to survive. The Mississippi River carried sediment and built the Wetlands of Louisiana. Without sediment from the river, our coast can’t be sustained or create land long-term.

Roots + Sediment = Stronger Soils, More Resilient Marshes. Some claim that freshwater marshes are inherently weaker than saltwater or brackish marshes against storm surge, but marshes with low mineral sediment input, like those near the Caernarvon Freshwater Diversion before Katrina, are weaker and more vulnerable to storms because of their lack of sediment. The Wax Lake Delta, located in Atchafalaya Bay, has been impacted by storm surge over the years, but quickly recovers and continues to grow and push out into the Gulf because of its supply of sediment. As a result, it is one of the few areas of our coast gaining land.

There is More to Sediment than Sand. There is a push to dredge the Mississippi River instead of using diversions. Sand dredged from the river bottom can and is being used to restore wetlands, but only dredging this material is not enough. Only around 20 percent of the sediment that the river carries is sand, the rest is silt and clays, which stay in suspension, never settling onto the bottom where it could be sucked up by dredges.

Diversions are Field-Tested and Scientifically Solid. Since 1989, CRCL has called for sediment diversions. The Mid-Barataria Sediment Diversion is one of the most studied and modeled projects in our state’s history. The Mississippi River built the delta’s wetlands, and most of the areas of Louisiana’s coast that have been maintaining or even gaining land instead of losing it are doing so because of regular sediment input from the Mississippi River.

The Mid Barataria Sediment Diversion is a Coastal Restoration Project, Not MRGO. Another recent tactic is to propose that the Mid-Barataria Sediment Diversion poses risks like those created by the dredging of the Mississippi River Gulf Outlet. MRGO destroyed areas through bank erosion and saltwater intrusion; the Mid-Barataria Sediment Diversion will build and maintain the land. Comparing a massive navigation channel like MRGO to a sediment diversion is comparing apples to oranges.

Diversions + Nutrients = Dynamic Estuaries. Some have argued that sediment diversions will cause so-called low-oxygen dead zones. The Mid-Barataria Sediment Diversion will bring more nutrients into the Barataria Basin, which will spur the growth of wetland plants. Those plants, in turn, will pull some of the excess nutrients from the diversion waters, helping reduce the dead zone in the Gulf.

To learn more, read “The Mississippi River is our Greatest Force for Building Land” by Dr. Renfro. Her article goes into more depth and explains more thoroughly the importance of large-scale sediment diversions.

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