Louisiana

These projects will build 11 square miles of new Louisiana wetlands by next year | Environment

Keeping two New Orleans lakes separate. Fill in the “Golden Triangle”. And the largest swamp cleanup project ever attempted by the state.

These are among projects under construction and on track to build nearly 11 square miles of new land by early 2023, state officials say. Though only a tiny fraction of the amount of land lost over the last century is still more than 5,300 football fields’ worth of wetlands that will help protect Louisiana from storm surges.

The projects are located in Orleans, Jefferson, Plaquemines and St. Bernard parishes and will use sediments dredged from lakes and bays in the region and the Mississippi River. Barry Richard, chief engineer with the state’s Coast Protection and Restoration Agency, gave an update on six major projects expected to cost about $527 million at a recent agency board meeting.

They are independent of the state’s unprecedented $2 billion plan to divert sediment from the Mississippi River to the Barataria Basin to create a more permanent solution to land loss in that area. This project, called Mid-Barataria Sediment Diversion, is expected to create and preserve about 20 square miles of new wetlands over half a century, although it has drawn strong opposition from commercial fishermen in the area.

CPRA Chair Chip Kline says the state’s success in rebuilding wetlands is being lost in debate over the diversion, which could be built as early as next year. If this project and the similar Central Breton sediment diversion are built on the east bank of the river, they will help extend the life of the new work highlighted in Richard’s update, state officials say.







New Orleans land bridge

Aerial view of the area in the Lake St. Catherine area where 600 acres of brackish marsh will be created.


New Orleans Landbridge Project

The $23.5 million New Orleans Landbridge Shoreline Protection and Marsh Creation project will restore 284 acres of brackish water along US 90 on the east shore of Lake Pontchartrain in the Lake St. Catherine area. The project aims to keep intact the land bridge between Lakes Pontchartrain and Lake Borgne.

This strip of land reduces the amount of hurricane storm surge that enters Lake Pontchartrain and threatens both the lakefront levees of New Orleans on the south coast and communities on the north coast, including Slidell, Mandeville and Covington. Containment banks for two out of three cells that will be filled with sediment to create a platform for swamp grasses have been completed.

The project involves the construction of articulated concrete mats to be placed along the shoreline of the Land Bridge’s Lake Borgne to reduce erosion caused by wave energy. The project is funded by the Federal Coastal Wetlands, Planning and Protection Act, with Louisiana paying approximately 15%.







Golden Triangle swamp creation

Schematic view of the 700-acre, $54.7 million Golden Triangle Marsh Creation project. Three wetland cells are created (purple outline on the left) with sediments dredged from Lake Borgne (green area). (Coast Defense and Restoration Authority)


Golden Triangle swamp creation

A $54.7 million wetland restoration plan in the Golden Triangle area near Lake Borgne’s flood barrier in the northwest corner of that lake is one of several projects delayed by a dredge shortage.

This project will eventually include the restoration of 700 acres – just over a square mile – lost over the years associated with the now closed Mississippi River-Gulf Outlet shipping canal.

State officials are working with the dredging company to bring it back to the Golden Triangle after the other project is completed, Richard said. The project is paid for with money from the BP Deepwater Horizon oil spill in 2010.







Lake Borgne Marsh Creation

Protected open water circuits are part of the Lake Borgne Marsh Creation project, which aims to attract migratory waterfowl once the surrounding marshland is restored. (Coast Defense and Restoration Authority)


Lake Borgne Marsh Creation

The Lake Borgne Marsh Creation project will restore 2,769 acres — over 4.3 square miles — along the south shore of the lake from Shell Beach to near Lena Lagoon, with $114.6 million from BP oil spill funds. It’s the largest single project attempted by CPRA, Richard said.

The contractor did indeed have a head start on construction ahead of its official start time, but the excavator was reassigned by the Army Corps of Engineers for maintenance dredging in the Barataria Pass. Richard said construction is expected to resume in November.

It is part of a larger strategy aimed at rebuilding the lake’s edge and swamp habitat in the region, with a focus on protecting local communities.

An unusual feature is the creation of two circular areas of open water in the midst of new wetland areas for migratory waterfowl shelters. It is also paid with BP spill money.







Biloxi Marsh Living Shoreline

Biloxi Marsh Living Shoreline

The Biloxi Marsh Living Shoreline project is designed to reduce the loss of sensitive wetlands along the southeastern section of Bayou La Loutre through the use of two types of artificial reef breakwater structures.







Biloxi Marsh Living Shoreline Products

One of these is a concrete pyramid that allows water to flow through, called Wave Attenuation Devices, or WADS. The other is a combination of interlocking concrete structures designed to look like baby strollers called ShoreJax. Both will be placed along 11 miles of the wetland margin where they are expected to be colonized by oysters in hopes that they will speed up the emergence of new oyster reefs.

Tests by the state in 2017 showed that within 3 1/2 years they would begin to see oysters clinging to their concrete sides.

This $66.6 million project will also be paid for with BP spill funds.







Spanish Pass Marsh and Ridge

Schematic of the 70% Completed Spanish Pass Marsh and Ridge Project. The purple area is the swamp created by channeling sediment from the Mississippi River into Barataria Bay. The yellow line is a ridge that will be planted with seedlings later this year. (Coast Defense and Restoration Authority)


Spanish Pass Marsh and Ridge

Construction on the Spanish Pass Marsh and Ridge project on the west bank of the parish of Plaquemines near Venice is more than 70% complete but work has been suspended to allow the Corps to use the dredger for river maintenance.

The excavator will return in March to complete the project, Richard said. It has been under construction since early 2021 and will include 1,538 hectares of new swamp and 130 hectares of ridge. The project’s cost of $91.5 million comes from BP spill funds.







Upper Barataria swamp landscape on a large scale

This graphic shows the three green cells where swamp is being restored as part of the Upper Barataria project. The black line is the 11 mile pipeline from the river to the project. In the orange and blue areas in the river, sediment is being dredged to be pumped through the pipeline.


Formation of the Upper Barataria Wetlands

The state’s new Upper Barataria Wetlands Creation Project, also designed to create 1,538 acres just north of the proposed Mid-Barataria Sedimentary Diversion site, is the latest extension of a plan to rebuild a land bridge spanning portions of the parishes of Plaquemines and Jefferson.

In 2009, the state began the first of five restorations, dubbed the Bayou Dupont Project, the first time the state has dredged sediment from the Mississippi River and pumped it inland through a six-mile pipeline to create new land .

The new project will use 8.4 million cubic meters of sediment pumped through portions of this pipeline and will cost $176 million paid for with BP funds.

https://www.youtube.com/watch?v=s-nUHXvD-YI

Containment levees for three new marsh cells were completed in early 2022, but the dredger was reassigned by the Corps to construct an underwater levee near Myrtle Grove to prevent saline water from the Gulf of Mexico from reaching the public water supply, a result of the extreme low flow river level.

That short-term project was completed last week and the dredge was returned to the Upper Barataria project on Friday, said a spokeswoman for NOAA, which oversees the restoration project.

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