Weighing In On Mid-Breton Sediment Diversion

The U.S. Army Corps of Engineers is seeking public comment on an upcoming study for the Mid-Breton Sediment Diversion.

by Erin Brown, Sportsmen Outreach Coordinator

One of the most critical restoration projects planned for the Mississippi River Delta is now open for public comment and the sportsman voice is needed to ensure a strong project is constructed. We have the backstory and information on how to participate in this important process.

South Louisiana is experiencing a major coastal land loss crisis, and with that comes the loss of one of the most unique cultures and biologically diverse fisheries in the world. It is a unique place due to the largest river system in the United States, the mighty Mississippi River, which originally built our current “bird foot’s delta” 1,000 years ago. The river deposited sand and silt throughout its bayous, tributaries, and marshes, constantly replenishing and nourishing the rich habitats throughout our coast. Levees were constructed along the river in the early 1900s, cutting off that natural annual sediment deposition during high river stage. Since then, Louisiana is losing a football field of land every 100 minutes, and has lost approximately 2,000 square miles since 1930. Couple this with devastation from hurricanes, sea level rise, and our sinking coast, and we have quite the concoction for a dying coast.

You may be asking, what is the solution?

In an effort to harness the power of the Mississippi River to rebuild land and nourish the coast, the Louisiana Coastal Protection and Restoration Authority (CPRA) has proposed a major large-scale sediment diversion on the east bank of the Mississippi River. Mid-Breton sediment diversion is a cornerstone of the state’s 50 billion-dollar, 50-year Coastal Master Plan. This diversion, located in Plaquemines Parish, is expected to begin construction by 2023. The exact location was chosen after extensive modeling had proven that this was a natural accumulation point for sediment in the river.

The Mid-Breton sediment diversion is expected to run up to approximately 75,000 cubic feet per second (cfs) when the river is high and carrying lots of sediment, and flowing at lower levels as the river stages drop. Gravity will be the driver, but the presence of gates will allow CPRA to modify operations to maximize land building and reduce flow at times when the river carries less sediment. The idea is to capture the maximum amount of available sediment carried by the river, usually during the rising stages of late winter and early Spring floods. The goal is to capture maximum sediment, while reducing the level of freshwater inundation to the brackish marshes. The Mid-Breton sediment diversion is expected to create 16,000 acres of new land over the next 50 years!

But how will this affect hunting and fishing?

You may be wondering how the sediment diversion might affect target species like speckled trout, redfish, largemouth bass, and ducks. These are the very questions that are appropriate to raise during scoping so they are clearly addressed in the Environmental Impact Statement (EIS). Obviously, we can anticipate fluctuating changes in salinity that track the natural rise and fall of the river, which will determine what can flow through the diversion. During diversion operations, salinities will decrease, and the location of target species will shift accordingly. Longer term, of course, habitat will change as the receiving basin adjusts to the new flow patterns and average salinities. But of course, habitat has been changing, getting saltier for a century, as can be seen in the disappearing marshes and the dead oaks on the sinking ridges. The idea is to reverse that process.

From fishing down in the Delacroix marsh, I have personally seen the population of largemouth bass greatly increased. The freshwater coming into this area has transformed and freshened this part of the estuary producing crawfish, freshwater catfish, bream, and frogs. Redfish seem to be unbothered by the changes to the area, and it is likely that the newly submerged aquatic vegetation will provide new habitat and cause a large population for redfish and even trout when the diversion is not operating.

Louisiana is also home to a large population of migratory waterfowl, approximately 7 million every year. A restored marsh will provide more habitat for these ducks and birds to nest in throughout the winter. The new freshwater plants will provide additional favorable duck feed furthering duck hunting opportunities of the east bank of the Mississippi River.

A part of the coastal master plan is restoring our coast through a suite of projects that work in tandem with one another- barrier island restoration, marsh creations, diversions, etc. The idea here is to create the healthy estuary gradient that once existed in Louisiana (as seen in the graphic below). This is the ideal habitat that all wildlife and fisheries need in order to thrive.

Estuary species illustration developed by Coalition to Restore Coastal Louisiana and LSU Coastal Sustainability Studio.
What does our coast look like without Mid-Breton and how do I get involved?

The future of Louisiana’s Sportsman’s Paradise looks pretty grim if we do not act quickly. The lands that you know and love to hunt and fish are in serious jeopardy. Most scientists agree that the answer is in harnessing the power of the Mississippi River through sediment diversions.

So as a concerned sportsman, you may be asking yourself what’s next and may be wondering how you can get involved. Currently, the Mid-Breton sediment diversion is undergoing the scoping process of the National Environmental Policy Act (NEPA). This is the first step in creating an Environmental Impact Statement (EIS) that analyzes possible positive and negative impacts of a project. Scoping determines which issues need to be examined by the EIS.

The Army Corps of Engineers is currently conducting scoping to solicit public interest and input on everything from how the Mid-Breton sediment diversion will affect the recreational and commercial fishery to impacts on threatened or endangered species to navigational impacts. Now is the time to share your comments, questions, or concerns involving the Mid-Breton sediment diversion.