Implementing the vision of a delta reconnected to its river
Restoring the Mississippi River Delta will take large-scale projects that can restore or imitate the river's natural processes. This involves the reintroduction of fresh water and sediment to the coastal system while preparing for future conditions of the delta ecosystem. Through principled management of site specific projects, we can rebuild the delta in a way that is sustainable for both communities and ecosystems.
Key Principles of Restoration
Restoration of a healthy, productive delta requires implementation and coordination of many strategies, including reconnecting the river to the delta through land-building sediment diversions, strategic use of dredged sediments to build and sustain wetlands and barrier islands, making changes in Mississippi River management, and adopting community resilience measures.
Many restoration projects are underway throughout the delta, but many more are needed as part of a comprehensive vision for the delta's future. Below are some of the most critical projects still needing action. Successfully implementing these will demonstrate the effectiveness of these restoration techniques, thereby leading to their expanded use throughout the delta.
Myrtle Grove Diversion – The Myrtle Grove diversion project was authorized in the 2007 Water Resources Development Act (WRDA) as a medium size diversion intended to mimic natural land-building processes by reintroducing sediment to the basin. Congress authorized a modification to the project to maximize land-building with the goal of protecting people and infrastructure during storm events. The receiving basin of this diversion, Barataria Bay, on the western side of the Mississippi River, has experienced some of the highest rates of land loss in coastal Louisiana – over 450 square miles since 1932.
The opportunity of Myrtle Grove inspired a unique collaboration between Louisiana’s Coastal Protection and Restoration Authority (CPRA) and Mississippi River Delta Coalition partners. For this project, the collaborative enlisted a team of experienced academic and technical consultants to undertake a comprehensive field data collection, physical, hydrodynamic and morphological modeling effort. This work has been used to assess the optimal location and capacity of a diversion to maximize land-building in the basin while taking into account possible impacts on navigation, water level and salinity. The results indicate that a pulsed diversion capturing 5% or more of the river’s flow during high river discharges delivers significantly more sediment and greatly increases land-building in Barataria Bay. Currently, an effort is underway to share this information with regional stakeholder groups and solicit their input.
MRGO and the Central Wetlands – The Mississippi River Gulf Outlet (MRGO), a shipping channel opened in the 1960s as a shortcut between the Gulf of Mexico to the Port of New Orleans, completely destroyed over 27,000 acres of wetlands and impacted over 600,000 acres of coastal ecosystem due to saltwater intrusion. Prior to construction of the MRGO, the coastal wetlands provided economic opportunities, helped clean water, and provided natural storm surge protection to nearby urban communities like the Lower Ninth Ward, New Orleans East, Chalmette, and Arabi.
Hurricane Katrina underscored the gravity of MRGO’s impact on wetlands and public safety when storm waves decimated the levees along the MRGO while the surge was still rising. This large-scale breach of levees resulted in catastrophic, deadly flooding of communities. In 2007, the U.S. Congress singled out the MRGO’s role in Katrina’s devastation by calling for the Army Corps to close the MRGO and to develop a plan for ecosystem restoration. We are working to ensure comprehensive restoration of this critical ecosystem. Visit www.MRGOmustGO.org to learn more and take action!
Atchafalaya River System – The magnificent Atchafalaya River Basin is the largest remaining river swamp in the United States and one of our country's last great wilderness areas. Thirty percent of the combined flow of the Mississippi and red Rivers is routed down the Atchafalaya River at the Old River Control Structure complex north of Baton Rouge. With this managed flow, two deltas are growing at the outlets of the river in Atchafalaya Bay, demonstrating clearly that the river can still build land. Still, the Atchafalaya River is not actively managed in any way to maximize this land-building process or to utilize its water and sediment resources to rebuild land to the east.
However, a hydrodynamic model of the Atchafalaya system is currently being developed to give scientists and policymakers a tool to help understand how water and sediment move through the system and how changes to the operation of the Old River control complex can contribute to rebuilding land and restoring the delta. Integrating the Atchafalaya system into delta restoration plans is essential, otherwise nearly one third of the resources available to effect restoration are being ignored.
Re-Envisioning the Delta
Even as restoration projects are implemented, scientists and Coastal Louisiana residents know that the delta as it exists today will not be the delta of the future. Major rivers have a natural tendency to shift over time. The Mississippi River and its Delta are more dynamic than most rivers, but over the past hundred and fifty years, man-made levees and other human engineering has straitjacketed the river on its current course. Today's rapid land loss and ecosystem degradation clearly demonstrate the unsustainable nature of the status quo.
Over the next 100 years, the path and shape of the Mississippi River from Old River Control (where the Atchafalaya splits off) to the current Birdsfoot Delta is likely to change, and with it so will the hydrology and geomorphology of the delta. Sea level rise and climate change will also fundamentally alter the landscape and biological composition of the delta. Louisiana is beginning to plan for these changes in the State Master Plan.
In addition to the State Master Plan, engineers and scientists from around the world are joining in a design competition to show how the lower Mississippi River and Delta of the future could look. Imperative to this effort will be showing how the delta can maintain its ecosystem and its economic and community roles while these fundamental changes take place.
- Coastal Protection and Restoration Authority of Louisiana, "Assessment of 'Lessons Learned' from the Operations of Existing Freshwater Diversions in South Louisiana."
- MRGO Must Go, "Mister Go Isn't Gone Yet."
- National Academy of Sciences, "Drawing Louisiana's New Map: Addressing Land Loss in Coastal Louisiana."
- Restore the Mississippi River Delta Campaign, "Central Wetlands Facsheet."
- Restore the Mississippi River Delta campaign, "Wetlands and Barrier Islands."
- U.S. Army Corps of Engineers, "West Bay Sediment diversion."