Recommended Plan for St. Tammany Parish Feasibility Study sent to USACE Headquarters for Review and Approval

USACE New Orleans District
Published April 9, 2024

New Orleans, La. – The U.S. Army Corps of Engineers, New Orleans District in conjunction with USACE Headquarters in Washington, D.C. has completed the District reviews of the St. Tammany Parish Louisiana Feasibility Study which investigated flood risk management and coastal storm risk management solutions to reduce the risk from flood damages caused by riverine, rainfall, and coastal storm flooding in St. Tammany Parish.


The Recommended Plan will be sent to the Army Corps Chief of Engineers for final review and approval. If approved, Recommend Plan would be submitted to Congress for project authorization.  To implement the recommended plan, USACE would need to secure both project authorization and subsequent appropriations from Congress.


The final review incorporates changes from the previous draft report release in the summer of 2023. These changes include new cost estimates with a new benefit to cost ratio and removal of the Mile Branch channel improvements in Covington, Louisiana.


The new estimated cost to complete the St. Tammany project increased from $4 billion to $5.9 billion. These changes were largely due to an increase in the contingencies applied to construction cost for the features, which address potential risk to changes in construction costs should the project be authorized and funded. Specifically for the nonstructural features, the percentage of funding allocated to development and oversight of the program was increased. The updated cost also reflects uncertainties at construction sites such as soil conditions.


The updated benefit to cost ratio is 1:6. This new figure takes into account construction of the 18.5-mile-long levee system in Slidell and the raising and floodproofing of 6,410 structures across the Parish. The project, once completed, would provide flood risk reduction to more than 26 thousand structures. The Mile Branch channel improvement was removed from the recommended plan after an updated economic analysis was run utilizing the revised cost estimate, and it was determined that the cost to implement the channel improvements exceeded the flood damages avoided, making the benefit to cost ratio below 1. The Mile Branch channel improvements were no longer an economically justified measure and removed from the Recommended Plan.  


The U.S. Army Corps, New Orleans District successfully transmitted The Final Revised Draft Integrated Feasibility Report and Environmental Impact Statement (IFR-EIS) to Headquarters on February 20, 2024. The Final IFR-EIS is currently in State and Agency Review, which is scheduled to end on May 3, 2024. Once State and Agency Review is completed, the final IFR-EIS will be posted on


For more information on the St. Tammany Feasibility study, visit



Melanie Oubre

Release no. 24-019