Next Steps for a Healthy Gulf of Mexico Watershed
Mississippi River Coastal Wetlands and Barrier Islands
Landscape at a Glance
The Mississippi River Delta, Coastal Wetlands and Barrier Islands Focal Area is located in the coastal parishes of southeast Louisiana, from the Vermilion Bay east to the Pearl River on the state line with Mississippi, and includes the offshore barrier islands and the associated bays and estuaries along the coast. These highly productive coastal habitats support millions of birds and a diverse assemblage of fish and wildlife species.
The focal area was historically formed through the active delta building process of the Mississippi River, and is continually being reshaped and reformed as freshwater and sediment makes its way into the Gulf. This confluence of the world’s third largest river with the Gulf has created vast stretches of fresh, intermediate, brackish and saline marshes; cypress swamps; bottomland hardwood forests; coastal flatwoods; sandy beaches and dunes; bayous; river channels and open water. This once seemingly boundless wetland ecosystem also supports thriving shipping, energy, seafood and recreation industries. However, this engine of economic and ecological productivity is threatened by the staggering annual losses of coastal wetlands and ongoing disruption of delta formation processes.
Levees, navigation channels, canals and dams have limited the Mississippi River’s ability to distribute sediments to the coast at the rate necessary to balance natural erosion, leading to extensive land loss. The diversity, productivity, and even the existence of coastal habitats are being further compromised by the increasing impacts of saltwater intrusion, sea level rise and more frequent tropical storms. These factors are responsible for Louisiana having the highest coastal wetland loss rate of any state in the nation, with a loss of approximately 16.6 square miles per year (more than 1,900 square miles since 1932). Ongoing restoration efforts are being funded through various means, including under the Coastal Wetlands Planning, Protection and Restoration Act (CWPPRA) and the state’s Comprehensive Master Plan for a Sustainable Coast. The Service supports and is engaged in these monumental restoration efforts which are directed at reducing, and ultimately reversing, coastal land loss.
Restoration of marsh habitats through sediment diversion, terracing and beneficial use of dredge material in this focal area are important for achieving population objectives for breeding mottled ducks (217,642 individuals) and wintering waterfowl (e.g., > 1.2 million individual blue-winged and green-winged teal, and > 700,000 gadwall). Significant populations of colonial waterbirds (e.g., snowy egrets, white ibis and tricolored herons) and seaside sparrows also occur in the fresh, brackish and salt marshes in this region. Offshore barrier islands provide important nesting habitats for significant populations of brown pelicans (objective of 21,000 pairs) and wintering shorebirds (notably the federally listed red knot and piping plover). The Gulf Coast Joint Venture has established objectives for many migrant shorebirds in this area as well, including: buff-breasted sandpipers (4,487 individuals), stilt sandpipers (45,076 individuals), and western sandpipers (96,060 individuals).
When restoring barrier islands, we recognize the need to incorporate a mosaic of habitat types that will not only benefit our trust resource species but also multiple other species. For example, a comprehensive restoration approach would not only include placing sediment and establishing vegetation that will provide loafing and nesting areas for colonial waterbirds such as brown pelicans, but would also incorporate components such as seagrass beds and protective nearshore reefs that will attract many species to these shallow habitats, including recreationally popular species like red drum, speckled trout, sharks and young tarpon. Appropriate river diversions that provide freshwater inputs and sediments will help to stabilize coastal marshes where egrets, ibis, and herons thrive as well as provide important spawning and nursery habitat for alligator gar. In addition, such diversions would help to re-build tidal marsh that provides cover and forage habitat for waterbirds as well as striped mullet, red drum, Gulf Coast striped bass and the diamondback terrapin (a Species of Greatest Conservation Need in Louisiana).
High Priority Actions Based on the Service’s Vision
Restore barrier island habitat such as the Chandeleur Islands to provide nesting habitat for brown pelicans and other colonial waterbirds, and to protect back barrier tidal flats to promote establishment and growth of seagrass beds.
- Restore Breton Island NWR by pumping offshore sand to reconstruct 352 acres of beach, dune and marsh habitat to support nesting brown pelicans and other colonial nesting waterbirds (currently in engineering and design phase funded under NRDA early restoration).
- Protect shoreline along the Breton Sound and Gulf by constructing a hardened “reef” barrier on the Breton Island NWR perimeter for wave attenuation; fill behind the barrier to the vegetated marsh with dredged material and then plant to provide additional erosion protection.
- Coordinate with the state of Louisiana’s ongoing Barrier Island Comprehensive Monitoring (BICM) and System-Wide Assessment and Monitoring Programs (SWAMP) to develop monitoring programs to evaluate the long-term effects of restoration of barrier islands and associated habitats, such as the status of at-risk species and other species of federal responsibility; the success of colonial nesting waterbirds (e.g., brown pelicans); marsh loss and creation; change in water depths; submerged aquatic plants; living shorelines (as the result of the beneficial use of dredge material); and the impacts of public use activities on natural resources.
- Perform dedicated dredging to restore marsh elevations within the Delta NWR. This restoration will greatly benefit nesting, loafing and feeding habitat for waterfowl and other water birds.
- Restore Barataria Bay barrier islands between Barataria Pass and Sandy Point to provide dune and back barrier marsh habitat and to provide storm surge and wave attenuation for the Barataria Basin.
Reconnect hydrology and construct river diversions into sediment-starved areas of the Mississippi River “Bird’s Foot Delta” to restore and enhance marsh habitat.
- Construct narrow cuts through berms or levees (crevasses) wherever feasible within the lower Mississippi River basin, to divert fresh water and sediment into shallow, open-water receiving areas to promote deltaic splay growth and nourishment of existing marsh. Using information from previous projects, construct crevasses at key locations to allow sediment-loaded water to flow into ponds or bays formerly closed off in order to build new splays, allowing these areas to become vegetated coastal habitats that support diverse populations of fish and wildlife.
- Dredge Main Pass to increase the flow of sediment into canals and crevasses on the Delta NWR to encourage marsh establishment and create beneficial splays that will culminate in hundreds of acres of new emergent marsh and increased erosion protection.
- Design and construct crevasses and dredge disposal projects to enhance and direct inputs and movement of freshwater within the Delta NWR and other lands influenced by Mississippi River flows. The objective is to create or restore emergent marsh and encourage low salinities for creation of stable freshwater spawning habitat for the alligator gar and other species dependent upon freshwater for part or all of their life histories.
- Construct projects such as sediment diversions into middle Barataria and Breton Sound Basins to build and maintain land (currently planned for 75,000 and 35,000 cfs capacity, respectively), in support of the Louisiana’s Comprehensive Master Plan for a Sustainable Coast.
Restore marsh and submerged aquatic vegetation within coastal bay and wetland systems through actions such as the placement of dedicated dredge sediment.
- Partner with the U.S. Army Corps of Engineers and the Louisiana Coastal Protection and Restoration Authority to use beneficial dredged materials from the Mississippi River to fill an open water bay that was originally marshland, and create new emergent marsh, on the Delta NWR just north of Pass-a-Loutre.
- Restore marsh in open pond areas over five acres in size, thereby fortifying the shoreline of the Delta NWR to ensure healthy and viable plant and animal communities, and the long-term resiliency of the refuge’s habitats.
- Dredge as much as seven miles of the Sauvage Bayou channel to increase aquatic habitats and deep water shelter and beneficially use the sediment on the Bayou Sauvage NWR to create new marsh and benefit aquatic species.
- Conduct reforestation and marsh planting projects in Blind Lagoon with the help of volunteers to restore damaged and eroded areas of the marsh and to provide colonial waterbird rookery habitat.
- Create approximately 550 acres of estuarine tidal marsh in northern Breton Sound in the vicinity of Hopedale, and approximately 8,510 acres of marsh in the New Orleans East Landbridge, to create new wetland habitat, restore degraded marsh and reduce wave erosion, in support of the Louisiana’s Comprehensive Master Plan for a Sustainable Coast.
- Restore approximately 450 acres of estuarine tidal marsh through beneficial use of dredge material along the north shore of Lake Pontchartrain on Big Branch Marsh NWR to benefit aquatic species and waterfowl.