Phoenix Marsh Creation – East Increment (BS-42)

Degraded marsh in coastal Louisiana.

Location

The project is located in Region 2, Breton Basin, Plaquemines Parish.

Problems

Two major causes of wetland loss for this area are sediment deprivation and saltwater intrusion. Altered hydrology and oil/gas development have exacerbated this loss. Much of the fresh and intermediate marsh that once existed earlier in this century has either converted to more saline habitats or has become open water as a result of oil/gas canals, subsidence, and a lack of sediment deposition. The 1984 to 2019 USGS land change rate is -0.78% per year.

Restoration Strategy

The project goal is to restore 392 acres of marsh in the open water areas between Bayou la Croix and River aux Chênes through the placement of dredged material via hydraulic dredging. This project will work syngeristically with projects to the east by creating continuity with the Breton Landbridge Marsh Creation (West) Project (BS-38) and the Mid Breton Landbridge Marsh Creation and Terracing Project (BS-32). This proposed first increment would extend the reach of the Breton Landbridge and is part of an overall, long-range, restoration goal to create/nourish 1,000 to 2,000 acres of intermediate marsh across 5 miles of the Breton Sound Basin from River aux Chênes to the Mississippi River.

Sediment will be hydraulically dredged from the Mississippi River. The dredged riverine sediments will be pumped via pipeline into two semi-confined disposal areas. Where feasible, existing marsh will be used as containment instead of containment dikes.

Vegetative plantings are not proposed in the marsh creation areas, and containment dikes will be gapped no later than year three post construction.

Service goals include restoration/protection of habitat for threatened and endangered species and other at-risk species. This project would restore habitat potentially utilized by the black rail, which is proposed for listing as a threatened species. The project could also benefit other species of concern including the saltmarsh topminnow and seaside sparrow.

The project was approved for Phase I Engineering and Design in January 2020.

The project is on Priority Project List (PPL) 29.

The Federal Sponsor is US Fish & Wildlife Service.

The Local Sponsor is CPRA.

North Delacroix Marsh Creation and Terracing (BS-41)

NOAA staff gather data to inform project design. 

Location

The project is located in Region 2, Breton Basin, St. Bernard Parish.

Problems

Hurricanes Katrina and Rita caused the majority of wetland loss in the project site. Wind erosion and saltwater intrusion have resulted in loss of marsh vegetation and wetland soils. Marsh loss has increased exposure of Delacroix to flooding from the east/ southeast. The 1984 to 2019 USGS loss rate is -1.4%/ year for the extended project boundary area.

Restoration Strategy

The project goal is to create and nourish approximately 389 acres of marsh and construct approximately 8,548 linear feet of terraces utilizing a layout to help protect the community of Delacroix.

Sediment would be hydraulically dredged from Lake Lery and placed into two confined disposal areas creating 322 acres of marsh and nourishing 67 acres of existing marsh. Two creation cells allow a channel for drainage. Approximately 8,548 ft of earthen terraces would be constructed. The terraces would be strategically placed east of the northern marsh creation cell and south of the southern cell. Dewatering of the marsh creation cells into areas adjacent to the terraces would take advantage of sediment laden water trapping the particulates to create additional marsh. Terraces would be planted with appropriate bare root plants 2.5 ft apart in one row per side and crown. Created marsh will not be planted.

Containment dikes will be gapped no later than three years after construction. Two additional areas of deteriorating marsh south and east of the proposed project will be investigated. Data acquisition for engineering and design would include an additional
349 acres to allow robustness for these additive or alternate features during Phase I.

The project was approved for Phase I Engineering and Design in January 2020.

This project is listed on Priority Project List 29.

The Federal Sponsor is NOAA NMFS.

The Local Sponsor is CPRA.