LWF hosting meeting Mar 31 feat. Tulane research on diversion benefits to reduce Bonnet Carré impacts

UPDATE (4/4/2022) – You can view the recording of this meeting here.

Louisiana Wildlife Federation will be hosting a meeting in St. Charles Parish for the public to learn about the multiple benefits of diversions to restore wetlands and reduce impacts of Bonnet Carré Spillway openings. The study will feature presentations from the Coastal Protection and Restoration Authority (CPRA) and Ehab Meselhe, Ph.D. of Tulane University.

Thursday, March 31, 2022
6:30 pm
Edward Dufresne Community Center
Meeting Rooms B & C (see map below)
274 Judge Edward Dufresne Pkwy, Luling, LA (directions)

Virtual Options
Zoom (registration required)
Facebook (see Facebook event)

The Bonnet Carré Spillway (BCS) is a flood-control structure and part of an overall flood control system for the Lower Mississippi River managed by the United States Army Corps of Engineers (USACE).  Recently the BCS has been operated more often than it has been in previous decades. The BCS diverts fresh floodwaters from the Mississippi River (along with sediment and nutrient loads) into Lake Pontchartrain. The flood protection benefits from BCS are well documented by the USACE.

Opening of Bonnet Carré Spillway in 2016

The Environmental Defense Fund (EDF) and Tulane University led a study to examine the utility of three river diversions identified and defined in the 2017 Coastal Master Plan —Maurepas, Union, and Ama — to function as auxiliary flood control options with a goal of reducing the magnitude or duration of operating the BCS.

The results of the first phase of the study showed that when the Ama and Union diversions are operated jointly, the amount of water flowing through the BCS was reduced between 57-61% while the number of days opened reduced by 47 days.

The goal of the latest study, Utilizing Upper Diversions in River Water Management, was to develop a model to represent the effects of flooding, sediment transport, water quality effects, and salinity dynamics resulting from the operation of the Bonnet Carré Spillway. This model would serve as a critical predictive tool that can be utilized to answer restoration and flood management questions. 

The Union Diversion would divert freshwater into West Maurepas swamp near Burnside to provide sediment for emergent marsh creation and freshwater and fine sediment to sustain existing wetlands.

Union Freshwater Diversion influence area

The Ama Diversion is a conceptual sediment diversion into Upper Barataria near Ama to provide sediment for emergent marsh creation and freshwater to sustain existing wetlands.

Ama Sediment Diversion influence area

Though both the Union and Ama diversions are in the State’s Master Plan, only one is preparing to move out of the “conceptual” phase and into feasibility and planning. The Union Diversion is currently included in the CPRA’s Fiscal Year 2023 Annual Plan. In this plan, funding is allocated for the planning phase of the project. The Ama Diversion, however, is still a conceptual project.

The River Reintroduction into Maurepas Swamp, which is also mentioned in Tulane’s study, is expected to begin construction this year. The USACE has just released an updated Supplemental Environmental Impact Statement selecting the project to be used as mitigation for the West Shore Lake Pontchartrain levee project. This decision means that CPRA meets environmental permit requirements for the project.

River Reintroduction into Maurepas Swamp benefit area (red outline)

The study confirms that using these “upper river” diversions will reduce the magnitude and duration of spillway openings, which in turn will improve the effects on wildlife, seafood productions, coastal communities and economies.

Join us on March 31 to hear from Dr. Ehab Meselhe of Tulane University as he discusses his research results. Attendees will have an opportunity to ask questions following presentations from CPRA and Dr. Meselhe. Representatives from the USACE will also be present to answer questions.

Related Links:

Tulane press releases for Phase 1 and Phase 2 of study
EDF’s Devyani Kar, PhD, blog article
Dr. Kar featured on recent American Shoreline Podcast episode.

Map of Edward Dufresne Community Center:



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