Breton-Chandeleur Basin Projects

The Breton-Chandeleur Basin is a marsh and adjacent sound bordered on the southeast by remnants of the Chandeleur barrier island chain and on the west by the Mississippi River. Habitats in the basin range from freshwater forests to barrier island habitat. Marshes in the mid-part of the basin have been starved of sediment for almost a century and have some of the highest recent marsh loss rates along the coast. In contrast, some portions of marshes in the lower basin periodically receive fresh water and sediment from the river during high flows and have much lower rates of loss.

The priority projects selected for this basin reintroduce sediment and freshwater flows from the river to slow the rate of land loss, strengthen soils and build new land in the mid-basin (Mid-Breton Sediment Diversion) and in the lower basin (Lower Breton Sediment Diversion). The ridge restoration projects (Bayou Terre aux Boeufs and Bayou la Loutre) will provide natural, structural protection by reducing wave and wind energy and buffering storm surge. Together, the diversions and ridges will prolong the life of the surrounding marshes while providing unique habitat for migratory birds.

Our 2017 Coastal Master Plan Priority Projects

Projects in the Breton-Chandeleur Basin Projects

1. Lower Breton Sediment Diversion
   This sediment diversion project is planned for lower Breton Sound along the east bank of the Mississippi River, likely across from Port Sulphur. Below the reach of the federal, man-made levees on the east bank, the brackish and salt marshes in the influence area have low rates of loss relative to many other parts of the coast. These low rates of land loss may be attributed to the sediment and fresh water these marshes periodically receive when the river overtops the banks during high flows. This project will divert sediment and fresh water into the basin to build new land, maintain existing marshes and increase the resiliency of the influence area to sea level rise and storm events.
2. Mid-Breton Sediment Diversion
   To be located along the east bank of the Mississippi River near Wills Point and upriver of the White Ditch siphon, this sediment diversion will convey fresh water and sediment into deteriorating marshes that drain into middle Breton-Chandeleur Basin. The swamps and marshes in the influence area have disappeared due to a combination of changes in the supply and distribution of fresh water, subsidence, salt-water intrusion, sediment starvation and storm events. This project will reconnect the influence area with the river and divert sediment and fresh water, building new land and sustaining existing marsh. If built in coordination with other projects in the basin, such as the Lower Breton Sediment Diversion and the Bayou Terre aux Boeufs Ridge Restoration, the Mid-Breton Sediment Diversion could build land more quickly. Additional benefits of this project include storm surge buffering for Plaquemines Parish.
3. Breton Ridge Restoration: Bayou Terre aux Boeufs stretches from Delacroix to Black Bay and has historically helped buffer storm surges for St. Bernard and Plaquemines parish communities and provided critical habitat for migratory birds and other wildlife. Severe erosion around the ridge and adjacent marsh has resulted in a loss and narrowing of the ridge. Subsidence of the ridge and saltwater intrusion has killed most of the trees on the ridge. This restoration will raise the ridge to an elevation of five feet to provide coastal upland habitat, restore natural hydrology, and provide wave and storm surge attenuation.
4. Breton Ridge Restoration: Bayou la Loutre begins in Yscloskey and extends into the southeastern Biloxi marshes. Bayou la Loutre ridge is actually two parallel natural levees flanking old Bayou la Loutre (Otter Bayou), which is part of the structural underpinning of the Biloxi marshes. Construction of the MRGO breached the ridges, dramatically altering the hydrology of the area and leading to saltwater intrusion and extensive wetland loss. The rock dam built across the MRGO in 2009 helped restore the hydrology but not the actual, previously lost marsh or ridge habitat. The ridge has suffered from subsidence, saltwater intrusion and canal breaches. The project will use dredged sediment, likely from Bayou la Loutre, to reestablish the ridge. This will add elevation to the ridge and help improve hydrology, provide storm surge protection, decrease saltwater intrusion and provide important resting habitat for migratory birds.