LaBranche Central Marsh Creation

Dredging of access/flotation canals for construction of I-10 resulted in increased salinity & altered hydrology that exacerbated conversion of wetland vegetation into shallow open water bodies. Land loss is estimated to be -0.543 percent/year based on USGS data from 1984 to 2011 within the extended project boundary.

The primary goal is to restore marsh that converted to shallow open water. Project implementation will result in an increase of fisheries and wildlife habitat, acreage, and diversity along with improving water quality. The proposed project will provide a protective wetland buffer to the railroad and I-10, the region’s primary westward hurricane evacuation route, and complement hurricane protection measures in the area.

The proposed solution consists of the creation of 762 acres of emergent wetlands and the nourishment of 140 acres of existing wetlands using dedicated dredging from Lake Pontchartrain. The marsh creation area will have a target elevation the same as average healthy marsh. It is proposed to place the dredge material in the target area with the use of retention dikes along the edge of the project area. If degradation of the containment dikes has not occurred naturally by Target Year 3, gapping of the dikes will be mechanically performed. Successful wetland restoration in the immediate area (PO-17 constructed in 1994) clearly demonstrates the ability for these wetlands to be restored using material from a sustainable borrow area (outlet end of Bonnet Carre Spillway). Engineering monitoring surveys of the marsh creation area and borrow area are planned as well.

This project is located in the Pontchartrain Basin (Region 1), St. Charles Parish. It is bounded to the north by the railroad running parallel to I-10, to the west by the marsh fringe just east of Bayou LaBranche, to the south by Bayou Traverse and to the east by marsh fringe west of a pipeline canal.

This project is on Priority Project List (PPL) 21.

The LaBranche Central 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 Reference Monitoring System

In 1990, the U.S. Congress enacted the Coastal Wetlands Planning, Protection and Restoration Act (CWPPRA) in response to the growing awareness of Louisiana’s land loss
crisis. CWPPRA was the first federal, statutorily mandated program with a stable source of funds dedicated exclusively to the short- and long-term restoration of the coastal wetlands of Louisiana. Between 1990 and 2016, 108 restoration projects were constructed through the CWPPRA program. These projects include diversions of freshwater and sediments to improve marsh vegetation; dredged material placement for marsh creation; shoreline protection; sediment and nutrient trapping; hydrologic restoration through outfall, marsh, and delta management; and vegetation planting on barrier islands.

The coastal protection and restoration efforts implemented through numerous CWPPRA projects require monitoring and evaluation of project effectiveness. There is also a need to assess the cumulative effects of all projects to achieve a sustainable coastal environment. In 2003, the Louisiana Office of Coastal Protection and Restoration (now CPRA) and the U.S. Geological Survey (USGS) received approval from the CWPPRA Task Force to implement the Coastwide Reference Monitoring System (CRMS) as a mechanism to monitor and evaluate the effectiveness of CWPPRA projects at the project, region, and coastwide levels (Steyer and others, 2003). The CRMS network is currently funded through CWPPRA and provides data for a variety of user groups, including resource managers, academics, landowners, and researchers.

The effectiveness of a traditional monitoring approach using paired treatment and reference sites is limited in coastal Louisiana because of difficulty in finding comparable test sites; therefore, a multiple reference approach using aspects of hydrogeomorphic functional assessments and probabilistic sampling was adapted into the CRMS design. The CRMS approach gathers information from a suite of sites that encompass a range of ecological conditions across the coast. Trajectories of changing conditions within the reference sites can then be compared with trajectories of change within project sites. The CRMS design not only allows for monitoring and evaluating the effectiveness of each project but will also support ongoing evaluation of the cumulative effects of all CWPPRA projects throughout the coastal ecosystems of Louisiana. Simulations made by using the resampling methodology described in Steyer and others (2003) indicated that 100 randomly selected reference sites would accurately represent the true composition of coastwide vegetation at a 95 percent confidence level. However, in order to detect a 20 percent change in coastal marsh vegetation between two time periods, at least 80 percent of the time, approximately 400 reference sites were needed. Because of land rights and other technical issues, 390 sites with a fixed annual sampling design were approved and secured for CRMS data collection. These 390 CRMS sites are located within nine coastal basins and four CWPPRA regions, covering the entire Louisiana coast. Site construction and data collection began in 2005.

Because of the quantity of products and data that will be produced over the lifetime of the CRMS project, a website (http://www.lacoast.gov/crms) was designed to be a one-stop shop for CRMS information, products, and data. The ecological data available through the website are linked to the official Louisiana CPRA database – the Coastal Information Management System (CIMS), which houses all CWPPRA monitoring data, on topics such as the following: hydrology, herbaceous marsh vegetation, forested swamp vegetation, soil properties, soil accretion, and surface elevation. Data provided by the Louisiana CPRA are available for downloading at https://cims.coastal.louisiana.gov/. The basic viewer (under Mapping) on the CRMS Web site provides a user-friendly interface for viewing information on specific sampling sites, including photos, data summaries, and report cards. Analytical teams are developing mechanisms by which individual sampling sites can be assessed in relation to other sites within the same marsh type, hydrologic basin, and CWPPRA project. These multi-scale evaluations will be presented on a “Report Card” tab within the basic viewer. The CRMS program is as dynamic as the coastal habitats it monitors. The program continues to develop new products and analysis tools while providing data for model improvement and scientific research. The CRMS Web site is the current dissemination mechanism for all activities related to the program. For a beginner’s guide to retrieving CRMS data, visit https://www.lacoast.gov/new/Ed/CRMS_Manual.pdf.

Reference:

Steyer, G.D., Sasser, C.E., Visser, J.M., Swensen, E.M., Nyman, J.A., and Raynie, R.C., 2003, A proposed coast-wide reference monitoring system for evaluating wetland restoration trajectories in Louisiana: Environmental Monitoring and Assessment, v. 81, p. 107–117.

Oyster Bayou Marsh Creation

Altered hydrology, drought stress, saltwater intrusion and hurricane induced wetland losses have caused the area to undergo interior marsh breakup. Recent impacts from Hurricane Rita in 2005 and Hurricane Ike in 2008 have resulted in the coalescence of Oyster Lake with interior water bodies increasing wave/wake related erosion. Based on USGS hyper temporal data analysis (1984 to 2011), land loss for the area is -0.75% per year. The subsidence rate is estimated at 0.0 to1.0 ft per century (Coast 2050, Mud Lake mapping unit).

The project boundary encompasses 809 acres. Specific goals of the project are: 1) create 510 acres of saline marsh in recently formed shallow open water; 2) nourish 90 acres of existing saline marsh; 3) create 17,500 linear feet of terraces; and, 4) reduce wave/wake erosion.

Approximately 510 acres of marsh would be created and 90 acres would be nourished. Sediment needed for the fill would be mined approximately one and a half miles offshore in the Gulf of Mexico. Half of the created acres would be planted. Tidal creeks and ponds would be constructed prior to placement of dredged material and retention levees would be gapped to support estuarine fisheries access to achieve a functional marsh. Approximately 17,500 linear feet of earthen terraces would be constructed and planted.

This project is in Region 4, Calcasieu-Sabine Basin, located west of the Calcasieu Ship Channel and south of the west fork of the Calcasieu River.

This project is on Priority Project List (PPL) 21.

The Oyster Bayou Marsh Creation project sponsors include:

• Federal Sponsor: National Marine Fisheries Service
• Local Sponsor: Coastal Protection and Restoration Authority

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

 

Terracing

CWPPRA Restoration Technique: Terracing

The goal of building terraces is to achieve some of the same objectives as full marsh creation but over a larger area of open water, where marsh creation alone is not feasible. Terraces are long, earthen berms that are built by mechanically dredging material and piling and shaping the material to a desired height. Most terraces average around 3 feet tall, with shallow side slopes and a wide base. This size and shape optimize the amount of terrace that falls in the intertidal zone and will support wetland vegetation.

The objectives of constructing terraces are several and depend upon the location in which they are built. These include acting as a sediment trap to help build new land, reducing wave fetch and erosion on adjacent marsh shorelines, creating habitat for fish and waterfowl, and improving water quality to promote the growth of aquatic vegetation. Terracing projects constructed under CWPPRA have achieved each of these goals, with sediment trapping being most evident near the openings of sediment-laden bays or navigational waterways.

Terracing has become a widely used technique that is expanding across the Gulf Coast because of the success and cost-effectiveness demonstrated through CWPPRA and privately funded projects. Although these features may not look like natural marsh and often use geometric configurations, they are able to perform a lot of the functions of natural marsh in areas that have become vast open water. Developing this cost-effective technique for use in areas that have few other restoration options is a testament to CWPPRA’s ability to adapt to funding constraints and a quickly changing environment.

TV-12 Little Vermilion Bay Sediment Trapping

 

 

 

 

Caminada Headlands Back Barrier Marsh Creation

The Caminada Headland has experienced some of the highest shoreline retreat rates in Louisiana. Historically the shoreline has migrated landward at about 40 feet per year. Between 2006 and 2011, shoreline migration increased dramatically, exceeding 80 feet per year in near Bay Champagne and 110 feet per year in the Bayou Moreau area. The increased losses occurred in the wake of Hurricanes Katrina and Rita in 2005 as the breaches remained open for an extended length of time. The losses were exacerbated by Tropical Storm Fay and Hurricanes Gustav and Ike in 2008. Significant prolonged breaches greatly increase the net export of sediment from the headland.

In addition to the shoreline migration, the area is also experiencing high loss rates of interior marshes. As the beach and dune continue to migrate landward, overwashed sediment will be lost into newly formed open water and land loss rates will be exacerbated. The continued deterioration of Caminada Headland threatens thousands of acres of wetland habitat as well as critical infrastructure, including Port Fourchon, LA Highway 1, and the lower Lafourche levee system.

The goals of this project are to: 1) Create and/or nourish 385 acres of back barrier marsh, by pumping sediment from an offshore borrow site; 2) Create a platform upon which the beach and dune can migrate, reducing the likelihood of breaching, improving the longevity of the barrier shoreline, and protecting wetlands and infrastructure to the north and west. The proposed project is expected to slow the current trend of degradation in the headland.

This project would create 210 acres of back barrier intertidal marsh and nourish 175 acres of emergent marsh behind 3.5 miles of the Caminada beach using material dredged from the Gulf of Mexico. The marsh creation and nourishment cells are designed to minimize impacts on existing marsh and mangroves. Assuming some natural vegetative recruitment, vegetative plantings are planned at a 50% density, with half planned at project year one and half planned at project year 3. Containment dikes will be degraded or gapped by year three to allow access for estuarine organisms.

The project area is defined as the area south of Louisiana Highway 1 between Belle Pass and Caminada Pass, directly behind Caminada Headland beach covering areas in and around Bay Champagne and areas east of Bayou Moreau. The Caminada Headlands Back Barrier Marsh Creation project is located along the Louisiana coastline in LaFourche Parish in CWPPRA Planning Region 2.

A kick-off meeting was held in June 2014. The project team has completed preliminary engineering and design, environmental compliance, real estate negotiations, operation & maintenance and monitoring planning, and a cultural resources investigation, all to the 95% design level as required by the CWPPRA standard operating procedures. The 30% design review meeting was held July 28, 2016 and the 95% design review was held on October 28, 2016. The Phase II Request for construction funding was presented to the CWPPRA Tech Committee on December 7, 2016.

This project is on Priority Project List (PPL) 23.

The Caminada Headlands Back Barrier Marsh Creation project sponsors include:

• Federal Sponsor: U.S. Environmental Protection Agency
• Local Sponsor: Coastal Protection and Restoration Authority

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

Freshwater and Sediment Diversions

CWPPRA Restoration Technique: Freshwater and Sediment Diversions

The present location of the Mississippi River has been confined by levees constructed in response to the devastating flood of 1927. Although necessary for protecting life and property, the levees prevent the natural processes of delta building and sediment deposition that are vital for sustaining wetlands. Without this nourishment, the wetlands will eventually succumb to subsidence, storms, and anthropogenic impacts.

The CWPPRA program has been finding solutions to optimize river resources and help rebuild wetlands with minimal impact to other stakeholders. Controlled diversions route river water through strategic locations in the levees to feed starving marshes. Crevasses, or cuts, are constructed through levees to allow passive creation of smaller deltas. Siphons suction fresh river water and direct flow into wetlands suffering from saltwater intrusion. Water-control structures and channel maintenance help distribute river water diverted from large-scale structures constructed under other authorities.

The river presents the greatest opportunity for rebuilding land but also the greatest challenges, as competing needs are inevitable. The human and natural environments must be able to coexist because they are inextricably connected. Together with stakeholders, CWPPRA projects are helping to reverse land loss on an ecosystem scale and support the economy on which coastal Louisiana has come to depend.

MR-03 West Bay Sediment Diversion

St. Catherine Island Marsh Creation & Shoreline Protection

The landfall of Hurricane Katrina in southeast Louisiana destroyed thousands of acres of marsh and other coastal habitats in the Lake Pontchartrain basin. The hurricane weakened the Lake Pontchartrain shoreline and large areas of interior marsh habitat were either lost or damaged near Chef Menteur Pass. This area has an estimated erosion rate of 18 ft./yr. or greater. A portion of the lakeshore is protected by rock dikes (Bayou Chevee PO-22, State only project and FWS funded project). Shorelines that are not protected by rock dikes will erode back into the shallow open water areas located near the shorelines further increasing erosion rates.

This project would extend the Bayou Chevee (PO-22) rock dike along approximately 33,324 LF of weakened Lake Pontchartrain shoreline. A 6,468 LF foreshore dike and a 13,851 LF revetment totaling 20,319 LF is proposed to be built along a portion of the Bayou Savauge NWR. This would protect approximately 201 acres. This project would also create/nourish 115 acres (100 acres of marsh creation and 15 acres of marsh nourisment). That marsh would be created by filling those sites with material hydraulically dredged from the bottom of Lake Pontchartrain. A combination of healthy established marshes, bayou ridges, and constructed earthen dikes would contain that material. All constructed containment dikes would be sufficiently gapped within 3 years to allow for exchange of nutrients and estuarine organisms. This project would work synergistically with other restoration projects in the area including CWPPRA, state, and Bayou Savauge National Wildlife Refuge projects.

The goals of the project are to 1) stop shoreline erosion due
to wind generated waves along 33,324 linear feet of the Lake Pontchartrain shoreline, preserving 201 acres (166 acres of marsh and 35 acres of shallow water) and 2) create/nourish 115 acres (create 100 acres of marsh and nourish 15 acres of marsh) landward of that shoreline protection.

Service goals include the protection/creation of habitat or improvement of habitat for species of concern (LDWF), priority species (JV), and threatened and endangered species (FWS). The creation of low salinity brackish intertidal marsh habitat would be beneficial to several species that are currently on these lists, including, but not limited to Black Rail, Mottled Duck, Brown Pelican, King Rail, and Saltwater Topminnow. Helping to improve habitat, especially on Federal and State owned lands, ensures the protection of those valuable resources in perpetuity and should be a priority.

This project is located in Region 1, Pontchartrain Basin, Orleans Parish.

This project was approved for Phase I Engineering and Design in January 2017 and is on Priority Project List (PPL) 26.

The St. Catherine Island Marsh Creation & Shoreline Protection project sponsors include:

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

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

Barrier Island Restoration

CWPPRA Restoration Technique: Barrier Islands

Barrier islands are known as coastal Louisiana’s first line of defense against destructive storm surge. These islands are a unique composite of beach, dune, marsh, and sand flats that host a tremendous variety of fisheries and wildlife, including endangered species. Barrier island restoration projects are designed to protect and restore the features unique to Louisiana’s barrier island chains. This type of project may incorporate a variety of restoration techniques, such as the placement of dredged material to increase island height and width, the placement of structures to protect the island from erosive forces, and the placement of sand-trapping fences, used in conjunction with vegetative plantings, to build and stabilize sand dunes.

Responsible for the majority of Louisiana barrier island restorations to date, CWPPRA has led the charge in barrier island restoration because it recognizes the ecological importance of barrier islands and their critical role in the defense of coastal Louisiana.

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

 

Marsh Creation

CWPPRA Restoration Technique: Marsh Creation

Marsh creation replicates the natural land-building process of the Mississippi River in a controlled, and much accelerated, fashion. Land is built by a pipeline dredge that removes sediment from a “borrow” site by using a specialized vessel outfitted with a drill, suction pump, and pipe. As the drill, or cutterhead, spins, it agitates sediment at the bottom of the borrow site. This sediment is then pumped with water into a pipe that carries the resultant slurry to the restoration site. Once the slurry is in place, the water runs off as the sediment settles to form new land. Native vegetation is then installed to jump-start wetland productivity. Marsh creation projects result in restored wetlands in areas that were open water just weeks before.

CWPPRA is striving to identify and construct projects that provide strategic benefits by holding together larger ecosystems and that use renewable sediment resources like the river. Over the course of 26 years, CWPPRA has been restoring one piece of broken marsh at a time, which cumulatively yields significant results over time. The long-term vision is to sustain these restored marshes by restoring part of the riverine processes that first built them.

PO-104 Bayou Bonfouca Marsh Creation Project

 

Bayou LaLoutre Ridge Restoration and Marsh Creation

Historic and current ridge habitat loss occurs in the form of subsidence and shoreline erosion along Bayou La Loutre. The shoreline erosion is caused by increased boat traffic diverted due to the closure of the MRGO channel. Ridge habitat consists of Live Oak Hackberry Maritime forest which is utilized by trans-gulf migratory bird species as a first and last stop when crossing the Gulf of Mexico. This critical habitat is rated as S1-Most Critically Imperiled (State Natural Heritage Program) and S2 priority by the state of Louisiana. Interior marsh loss along Lena Lagoon is caused by subsidence, sediment deprivation, increased wave fetch and construction of access and navigational canals. The integrity of the Lena Lagoon shoreline has been breached, and loss of this wetland buffer will expose the La Loutre ridge to highly erosional winter storm events.

The goal of the project is to create an approximately 31.7 acre ridge feature with material from bucket dredging Bayou La Loutre. Additionally dredged material from Lake Borgne will create 163 acres of marsh and nourish approximately 258 acres of marsh along Lena Lagoon (421 acres total).

The proposed project will create approximately 5.46 miles (28,855 ft) of ridge along Bayou La Loutre and 24.4 acres of Live Oak/Hackberry Maritime forest habitat. The ridge habitat will be built centerline along the bank of the bayou. The structure will have a +4 elevation with a 5:1 slope on the bayou side and 3:1 slope on the marsh side. Additionally the newly created ridge will include herbaceous and woody plantings with smooth cord plantings along the toe. The Lena Lagoon site will create and nourish approximately 421 acres of marsh using sediment dredged from Lake Borgne. Lena Lagoon will have a semi-confined south and east flank and a fully confined north flank. Containment will be degraded as necessary to re-establish hydrologic connectivity with adjacent wetlands.

This project is located in Region 1, Lake Pontchartrain Basin and Breton Basin, St. Bernard Parish.

This project was approved for Phase I Engineering and Design in January 2017 and is on Priority Project List (PPL) 26.

The Bayou LaLoutre Ridge Restoration and Marsh Creation project sponsors include:

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

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