Boston Canal/Vermilion Bay Bank Protection (TV-09)

Construction of the Gulf Intracoastal Waterway, Boston Canal, and oilfield canals has greatly increased tidal exchange between Vermilion Bay and the adjacent marshlands to the north, particularly near their confluence with Vermilion Bay. This tidal exchange, combined with the effects of wave action from the bay and boat wake from traffic on the canal, has contributed to significant shoreline erosion along the Vermilion Bay shoreline. This same set of problems has also caused shoreline erosion along Boston Canal, particularly near its confluence with Vermilion Bay.

Rock dikes configured as sediment traps were constructed along the shoreline at the mouth of Boston Canal to promote sediment deposition and protect the shoreline and adjacent wetlands from continued wave-induced erosion. Vegetation was planted along 14 miles of the Vermilion Bay shoreline to act as a wave buffer and decrease shoreline erosion rates.

The project encompasses 466 acres of brackish marsh along approximately 16 miles of Vermilion Bay’s northern shoreline adjacent to Boston Canal. Running from the Oaks Canal to Mud Point, the project is located roughly 6 miles southeast of Intracoastal City, Louisiana, in Vermilion Parish.

Following the construction of the rock dikes, as much as 4.5 feet of sediment has  vertically accreted in the lee, or windsheltered regions, of the structures. The dikes and vegetative plantings have increased vegetation cover, resulting in 57
acres of land growth. The shoreline has been stabilized at the mouth of Boston
Canal.

The survivorship and vegetation cover percentage along the shoreline were more pronounced in areas where native vegetation did not exist. Survivorship and percent cover were least pronounced when marshhay cordgrass (Spartina patens) was planted in established stands of roseau cane (Phragmites australis). Overall survivorship of planted smooth cordgrass (Spartina alterniflora) was over 90% after 12 months. Current coverage is nearing 100%. The 2005 OM&M Report concluded the sediment build-up behind the dike on the east and west sides is continuing and vegetation has taken over the exposed mud flats. Elevation data show an increase in sedimentation behind the rock breakwater.

This project is on Priority Project List 2.

Federal Sponsor: NRCS

Local Sponsor: CPRA

Hydrologic Restoration and Vegetative Planting (BA-34-2)

Problems:

The Lac des Allemands River Basin Initiative identified the following specific problems within the Lac des Allemands Watershed: drainage impairments; water quality impairments; loss of marsh; and decline of cypress forest. Many years of study by Louisiana State University researchers in these swamps have demonstrated that, because of impoundment, subsidence, and inadequate accretion of sediments and organic matter, some areas are already highly stressed and converting to open water, floating aquatic plants, and fresh marsh. Also, the Coast 2050 report suggests that other areas of the swamps throughout the basin will likely convert to open water or floating marsh by the year 2050. These problems are caused by the loss of river water along with the associated sediment and nutrients necessary for swamp health. The loss of river water can be attributed to the leveeing of the Mississippi River. Impoundment caused by roads, drainage canals, and spoil banks is also a major cause of degradation of these swamps.

Restoration Strategy:

The original proposed restoration strategy included installing two small siphons (averaging 400 cubic feet per second) to divert water from the Mississippi River; gapping spoil banks on Bayou Chevreuil; gapping spoil banks along the borrow beside Louisiana Highway 20; installing culverts under Louisiana Highway 20; improving drainage in impounded swamps; and planting cypress and tupelo seedlings in highly degraded swamp areas.

The proposed diversion from the Mississippi River was to bring fresh water, fine-grained sediments, and nutrients into the upper des Allemands swamps, which would have helped maintain swamp elevation, improve swamp water quality, and increase productivity and regrowth of young trees as older trees die. However, after hydrologic modeling and more detailed engineering/design and cost estimation, it was determined that the siphon would cost far more than originally anticipated. For that reason, the CWPPRA Task Force approved the project sponsors’ request to re-scope the project to eliminate the siphon feature, and to focus on the remaining project features.

Location: The project is located West of Lac des Allemands in St. James Parish, Louisiana, south of the town of South Vacherie, bordered on the south by Bayou Chevreuil, and on the east by LA Highway 20.

Progress to Date: The Louisiana Coastal Wetlands Conservation and Restoration Task Force approved Phase 1 funding in January 2001. In June 2013, the Task Force approved a request to change the scope of the project to eliminate a siphon feature and focus on the remaining original hydrologic restoration and vegetative planting project features. The Louisiana Coastal Protection and Restoration Authority performed the engineering and design services. Design was completed in October 2015 and Phase 2 funds for construction was approved by the Task Force in January 2016. Construction activities for excavation and placement began in October 2017 and ended on December 20, 2017, vegetative plantings occurred in late January, and officially completed on February 2, 2018.

The three (3) principal project features included:

1. Eight (8), 400-foot-long, strategically designed gaps were cut in the northern Bayou Chevreuil spoil bank to reverse the effects of impoundment;

2. Sixteen (16) spoil placement areas were created on each side of the channel banks; (1 placement area on both sides of each gap) to beneficially use the dredged material on site;

3. Seven hundred (700) Bald Cypress and one hundred (100) Water Tupelo saplings were planted in the constructed spoil placement areas to start swamp regeneration and swamp productivity.

This project enhanced 2,395 acres of swamp habitat that would have continued to degrade without the project.

This project is on Priority Project List (PPL) 10.

The sponsors include:

Federal Sponsor: U.S. Environmental Protection Agency

Local Sponsor: Coastal Protection and Restoration Authority (CPRA)

 

 

Coastwide Vegetative Planting (LA-39)

 

The coastal restoration community has long recognized the benefits of vegetative plantings in restoration. Many marsh creation and most terracing projects require plantings to insure success. Coastal shoreline plantings have also proven to be very effective and some have demonstrated the ability to not only stop shoreline erosion but to facilitate accretion, the process of increasing sediments. Recent hurricane events have exposed a need to have a mechanism in place where large-scale planting efforts can be deployed in a timely manner to specifically targeted areas of need, anywhere along the coast. Although the CWPPRA program can fund specific largescale planting projects, the normal program cycle for individual projects can delay needed restoration plantings for a number of years.

The goals of this project are to facilitate a consistent and responsive planting effort in coastal Louisiana that is flexible enough to routinely plant on a large scale and be able to rapidly respond to critical areas of need following storm or other damaging events. This project set up an advisory panel consisting of representatives from various state and federal agencies who would assist in the selection of projects for funding. The project also set up a mechanism by which project nominations would be submitted for consideration. The equivalent of 90 acres of interior marsh and 40,000 linear feet of coastal shoreline will be planted per year over a 10 year period to effectively create/protect a total of 779 net acres of marsh over the 20-year project life.

The project features are located in the coastal zone of Louisiana.

This project is on Priority Project List 20. Three sites have been planted with Year One funding, and three sites are scheduled to be planted in 2014 with Year Two funding.

 

Federal Sponsor: NRCS

Local Sponsor: CPRA

New Orleans Landbridge Shoreline Stabilization & Marsh Creation (PO-169)

Since 1956, approximately 110 acres of marsh has been lost along
the east shore of Lake Pontchartrain between Hospital Road and
the Greens Ditch. One of the greatest influences of marsh loss in
the area can be attributed to tropical storm impacts. Wetland losses
were accelerated by winds and storm surge caused by Hurricane
Katrina, which converted approximately 70 acres of interior marsh
to open water. Stabilizing the shoreline and protecting the
remaining marsh would protect natural coastal resources dependent
on this important estuarine lake, communities that thrive on those
resources, the Fort Pike State Historical Site, and infrastructure
including U.S. Highway 90. USGS land change analysis
determined a loss rate of -0.35% per year for the 1984 -2011
period of analysis. Subsidence in this unit is relatively low and is
estimated at 0-1foot/century (Coast 2050).

Lake Pontchartrain supports a large number of wintering
waterfowl. Various gulls, terns, herons, egrets, and rails can be
found using habitats associated with Lake Pontchartrain, which has
been designated as an Important Bird Area by the American Bird
Conservancy. Restoring these marshes will protect the Orleans
Landbridge and will help to protect fish and wildlife trust resources
dependent on these marsh habitats, particularly at-risk species and
species of conservation concern such as the black rail, reddish
egret, brown pelican, mottled duck, seaside sparrow, king rail, and
the Louisiana eyed silkmoth.

Borrow material will be dredged from areas within Lakes St.
Catherine and Pontchartrain to create 169 acres and nourish 102
acres of brackish marsh. Containment dikes will be constructed
around four marsh creation areas to retain sediment during
pumping. The lake shorelines will be enhanced with an earthen
berm to add additional protection from wind induced wave fetch.
Containment dikes that are not functioning as shoreline
enhancement will be degraded and/or gapped. Vegetative plantings are
proposed including five rows along the crown and two rows
along the front slope of the shoreline protection berm, as well as
within the marsh platform area.

The project is located in Region 1, Pontchartrain Basin,
Orleans Parish, flanking U.S. Highway 90 along the east shore of
Lake Pontchartrain and areas surrounding Lake St. Catherine.

This project was approved for Phase I Engineering and Design in
January 2015.

This project is on Priority Project List (PPL) 24.

The New Orleans Landbridge Shoreline Stabilization & Marsh Creation sponsors include:

• Federal Sponsor: U.S. Fish and Wildlife Service
• Local Sponsor: Coastal Protection and Restoration Authority

 

 

LaBranche East Marsh Creation

Dredging of access and flotation canals for the construction
of I-10 and the Illinois Central Railroad resulted in increased
salinity and altered hydrology in the area that exacerbated
the conversion of wetland vegetation into shallow open
water bodies.

The project’s primary goal is to restore marsh that has been
converted to open water. Project implementation will result
in an increase of wildlife and fisheries habitat, acreage and
diversity, along with improving water quality. In addition,
the project will provide a storm buffer protection to I-10, the
region’s primary westward hurricane evacuation route, and
complement hurricane protection measures in the area.
Project features consist of the creation of 729 acres of marsh
and the nourishment of 202 acres of existing marsh using
dedicated dredging from Lake Pontchartrain. In addition,
10,000 linear feet of tidal creeks will be created. The marsh
creation area will have a target elevation the same as average
healthy marsh for this region. Plans are to place the dredge
material in the target area with the use of low level, noncontinuous
retention dikes along the edge of the project area
allowing overtopping of material to nourish the marsh fringe.
Vegetative plantings will be utilized in the areas deemed
most critical by the project team. Successful wetland
restoration in the immediate area (PO-17) clearly
demonstrates the suitability and stability of soil and material
availability from a sustainable borrow area.

The project features are located between Lake Pontchartrain
and I-10 in St. Charles Parish, Louisiana. It is bounded on
the west by the Fall Canal and the Bayou LaBranche
Wetland Creation Project (PO-17) and the east by a pipeline
canal.

This project is on Project Priority List (PPL) 19.

The LaBranche East Marsh Creation project sponsors include:

• Federal sponsor: Natural Resources Conservation Service
• Local sponsor: Coastal Protection and Restoration Authority

Keep up with this project and other CWPPRA projects on the project page.

 

Coastwide Vegetative Planting

The coastal restoration community has long recognized the benefits of vegetative plantings in restoration. Many marsh creation and most terracing projects require plantings to insure success. Coastal shoreline plantings have also proven to be very effective and some have demonstrated the ability to not only stop shoreline erosion but to facilitate accretion, the process of increasing sediments. Recent hurricane events have exposed a need to have a mechanism in place where large-scale planting efforts can be deployed in a timely manner to specifically targeted areas of need, anywhere along the coast. Although the CWPPRA program can fund specific large-scale planting projects, the normal program cycle for individual projects can delay needed restoration plantings for a number of years.

The goals of this project are to facilitate a consistent and responsive planting effort in coastal Louisiana that is flexible enough to routinely plant on a large scale and be able to rapidly respond to critical areas of need following storm or other damaging events. This project set up an advisory panel consisting of representatives from various state and federal agencies who would assist in the selection of projects for funding. The project also set up a mechanism by which project nominations would be submitted for consideration. The equivalent of 90 acres of interior marsh and 40,000 linear feet of coastal shoreline will be planted per year over a 10 year period to effectively create/protect a total of 779 net acres of marsh over the 20-year project life.

The project features are located in the coastal zone of Louisiana.

This project is on Priority Project List (PPL) 20.

The Coastwide Vegetative Planting project sponsors include:

• Federal Sponsor: Natural Resources Conservation Service
• Local Sponsor: Coastal Protection and Restoration Authority

Keep up with this project and other CWPPRA projects on the project page.

 

Wetland Plants

Plants are a vital piece of healthy and sustainable wetland ecosystems. Plants are the base of the food chain and can build new layers of organic material on top of wetlands which helps them keep pace with subsidence and rising waters. Wetland vegetation reduces erosion primarily by dampening and absorbing wave and current energy and by binding and stabilizing the soil with roots. Coastal wetland plant species are indicators of soil and hydrologic conditions. The amount and salinity of water in an area influence which plants grow there. Scientists often classify Louisiana marshes into four types: fresh, intermediate, brackish, and saline.

The Coastal Wetlands Planning, Protection, and Restoration Act puts native wetland plant benefits to use through restoration techniques that include vegetative plantings. Vegetative planting projects are used both alone and in conjunction with barrier island restoration, marsh creation, shoreline protection, and sediment and nutrient trapping restoration techniques. These projects use flood-and salt-tolerant native marsh plants that will hold sediments together and stabilize the soil with their roots as they become established in a new area.

BA-38 Barataria Barrier Island Complex Project: Pelican Island and Pass La Mer to Chaland Pass Restoration

 

 

 

 

CWPPRA

Did you know:

CWPPRA has protected, created, or restored approximately 96,806 acres of wetlands in Louisiana.

The Coastal Wetlands Planning, Protection, and Restoration Act has funded coastal restoration projects for 26 years. Presently, CWPPRA has 153 total active projects, 108 completed projects, 17 active construction projects, 23 projects currently in Engineering and Design and has enhanced more than 355,647 acres of wetlands . These projects provide for the long-term conservation of wetlands and dependent fish and wildlife populations. Projects funded by CWPPRA are cost-effective ways of restoring, protecting, and enhancing coastal wetlands. CWPPRA has a proven track record of superior coastal restoration science and monitoring technique in Louisiana. The success of the CWPPRA program has been essential in providing critical ecosystem stabilization along Louisiana’s coast and has provided pioneering solutions for land loss.

Visit CWPPRA’s website for more information!

Plants of the Wetlands

Found at the interfaces of land formations and water, smooth cordgrass (Spartina alterniflora) is an herbaceous, native grass that densely inhabits shorelines. Compact, vegetative smooth cordgrass colonies grow along shorelines and inter-tidal flats of coastal wetlands such as canal banks, levees, marshes, barrier islands, and other regions of soil-water interface. This grass is highly adaptable to a variation of water depths and salinity levels making it a resilient species heavily used for coastal restoration. With an extensive rhizome system, smooth cordgrass is also highly effective as a soil stabilizer for loose soils, contributing to anchorage of the plants and sediment, as well as decrease of erosion effects. Smooth cordgrass acts as a natural buffer which dissipates energy of storm surge and wind impact to interior lands.

The Coastal Wetlands Planning, Protection, and Restoration Act frequently uses smooth cordgrass plugs during vegetative plantings due to the plant’s insensitivity to water and salinity levels, and its success in significant erosion protection to shorelines.

Losing Wetlands

Did you know:

Louisiana contains approximately 40% of the wetlands of the continental United States, but it experiences about 80% of its wetland losses.

Although the greatest amount of wetlands are located in Louisiana, subsidence, sea level rise, and anthropogenic activities are among the major factors contributing to the current state of Louisiana’s fragile and diminishing coastal wetlands.  Louisiana loses wetlands at an average rate of one acre per hour. If the current rate of loss is not slowed by the year 2040, an additional 800,000 acres of Louisiana’s wetlands will disappear, advancing the shoreline inward as much as 33 miles in some areas. CWPPRA is fighting to combat the speed of land loss by protecting, restoring, and creating the nation’s wetlands.

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