Central Wetlands Marsh Creation and Diversion

Combination Projects

Central Wetlands Marsh Creation and Diversion

This diversion and marsh creation project will synergistically benefit the Central Wetlands Unit ecosystem in New Orleans and St. Bernard Parish, an area of nearly 30,000 acres of wetland that was once mostly a mix of cypress-tupelo swamp and bottomland hardwood forest. Now a predominantly brackish marsh habitat, this area has been dramatically affected by human-made forces. Logging; leveeing of the Mississippi River; construction of oil, gas and navigation canals; and the construction of the now-closed Mississippi River-Gulf Outlet (MR-GO) have all impacted the Central Wetlands ecosystem. Regional MRGO-area ecosystem restoration will help rebuild and sustain marsh and swamp, providing storm surge protection for New Orleans and nearby communities.

The diversion project will benefit the Central Wetlands near Violet in St. Bernard Parish by providing sediment for emergent marsh creation and freshwater and nutrients to sustain existing wetlands.

The marsh creation project, with a footprint of approximately 3,800 acres in the Central Wetlands near Bayou Bienvenue, will create new wetland habitat, restore degraded marsh and reduce wave erosion.

About This Project

Project ID: 014a & 040

Parish: Orleans, St. Bernard

Type: Combination Projects, Fresh Water Diversion, Marsh Creation

Project Implementation

Project 1: Central Wetlands Diversion

Coastal Master Plan Project ID: 014a
Region: Pontchartrain
Parish: St. Bernard
Description: Diversion into Central Wetlands near Violet to provide sediment for emergent marsh creation and freshwater to sustain existing wetlands, 5,000 cfs capacity (modeled at a constant flow of 5,000 cfs, independent of the Mississippi River flow).
CPRA Project Factsheet

Project 2: Central Wetlands Marsh Creation

Coastal Master Plan Project ID: 040
Region: Pontchartrain
Parish: St. Bernard, Orleans
Description: Creation of marsh within a footprint of approximately 3,800 acres in Central Wetlands near Bayou Bienvenue to create new wetland habitat, restore degraded marsh, and reduce wave erosion.
CPRA Project Factsheet

Aerial photograph of the Central Wetlands in 2018. Photo Credit: National Wildlife Federation
Location of the Central Wetlands in the Pontchartrain Basin. The wetlands are surrounded by impoundments including the MRGO, 40 Arpent Levee and the newly built hurricane protection system around New Orleans.

What is a Diversion Project?

Graphic depiction of Diversion Projects by SCAPE. Found in 2023 Coastal Master Plan.

Graphic by SCAPE, Published in 2023 Coastal Master Plan

Diversions mimic nature’s historic land-building processes by using the power of the river to move sediment and fresh water from the river into nearby basins. This project type can not only build new land but also provide a sustainable source of sand and mud necessary to sustain and increase the health of existing wetlands over time. Sediment diversions can also re-establish or maintain the fresh end of the estuary, originally lost to saltwater intrusion, ensuring that the range of fresh to saltwater habitats that makes Louisiana’s estuaries so productive persists into the future. Sediment diversions also help sustain nearby marsh creation, barrier island and ridge restoration projects.

Other Diversion Projects

What is a Marsh Creation Project?

Graphic depiction of Marsh Creation Projects by SCAPE. Found in 2023 Coastal Master Plan.

Graphic by SCAPE, published in 2023 Coastal Master Plan.

Marsh creation or “dredging” uses sediment from the Mississippi River, nearby water bottoms or offshore shoals to build land in shallow, open water areas, typically where land has been lost. These projects can build land fairly quickly, but will eventually fall victim to the same process that caused the land to disappear originally. This type of project can be used in conjunction with sediment diversions to trap sediment, and sediment diversions can lengthen the lifespan of marsh creation projects by providing a continual source of sediment to the new marsh surface.

Other Marsh Creation Projects

Getting Muddy: Pontchartrain Conservancy

Members of Pontchartrain Conservancy’s Science team recently visited the Central Wetlands to do their part in restoring Louisiana’s wetlands. The team was able to plant 250 Vallisneria americana (wild celery or eelgrass) to help prevent erosion, clean the water column, and provide a spawning ground for fish and crabs. Pontchartrain Conservancy is part of the Central Wetlands Reforestation Collective with Coalition to Restore Coastal Louisiana, Common Ground Relief, The Lower 9th Ward Center for Sustainable Engagement and Development and Docville Farm.

Look for the next volunteer opportunity to join the cause: https://centralwetlands.org/