Atchafalaya Sediment Delivery (AT-02)

A bucket dredge is shown removing sediment from a shoaled-in channel in order to help reestablish water and sediment flow within the Atchafalaya Delta.

Location

The project is located east of the lower Atchafalaya River navigation channel in the Atchafalaya River Delta, approximately 19 miles southwest of Morgan City, Louisiana, in St. Mary Parish.

Problems

Growth of the lower Atchafalaya Delta has been reduced as a result of maintenance of the Atchafalaya River navigation channel. Delta development in the shallow waters of Atchafalaya Bay is dependent on distributary flows and the diversion of sediments into over-bank areas through crevasse channels.

Because of the placement of material dredged from the navigation channel and sediment accumulation within the channels that decrease flow efficiency, the open crevasse channels are frequently short-lived. As riverflow through a crevasse channel is reduced, the amount of sediment that can be deposited in the delta is likewise reduced, resulting in decreased marsh development.

Restoration Strategy

The purpose of this project is to promote natural delta development by reopening two silted-in channels and using those dredged sediments to create new wetlands. Approximately 720,000 cubic yards of sediment were dredged from Natal Channel and Castille Pass in 1998. Over 12,000 feet of channel were reopened, and more than 280 acres of new habitat were created by the strategic placement of the dredged channels’ sediments. By reestablishing water and sediment flow into the eastern part of the Atchafalaya Delta, an additional 1,200 acres of new habitat are expected to be naturally created over the life of the project.

Progress to Date

Construction was completed in 1998. A pre- versus post-construction habitat analysis using aerial photography indicated that, while there was an increase in land of 78.4 acres, the majority of the habitat created was represented by forested wetland (50.1 acres), while fresh marsh and upland barren habitats accounted for 14 acres gain each. Although many of the dominant plant species are present in both created and reference areas, the created areas contained different plant communities when compared to any time period in the development of a natural crevasse splay that served as a reference area for this project. Although the long-term effects on submerged aquatic vegetation (SAV) are unclear, habitat mapping indicated an increase in SAV habitat of 221.5 acres from 1997 to 1998, but this is very close to the increases that were reported in the project area pre-construction. Satellite imagery indicates that there have been significant increases in emergent acreage from 1998 to 2008.

This project is on Priority Project List 2.

The Federal Sponsor is National Marine Fisheries Service.

The Local Sponsor is CPRA.

Sustainable Fisheries

Some of you may remember the 1989 film “Field of Dreams,” and perhaps the famous quote “If you build it, he will come.” Meant as motivation to build a baseball diamond in a corn field, the line encourages dreaming big and following your passion. It can also apply directly to environmental protection and restoration. CWPPRA builds wetlands, and ecologically diverse communities come. They may take a long time, but they will come. Creating a resilient environment requires hard work, and the environment will return on investment many times over.

Biodiversity has a massive positive effect on the productivity of a system, [2] and we in Louisiana have some of the most productive wetland ecosystems in the United States. Coastal fisheries today produce about 40% of the world’s wild-caught seafood, according to the WWF, [1] and wild-caught fish rely heavily on a healthy ecosystem to produce populations large enough to harvest.  Unfortunately, many fish communities are over- exploited and have a lot of bycatch, causing  species declines and shifts in the health of the community. It doesn’t have to be this way, though. Sustainable fishing is an achievable goal.

By using our bountiful resources and productive wetlands, we can cultivate thriving ecosystems that don’t need much maintenance at all. A perfect model would require no feed, no destructive fishing methods like trawling or wasteful bycatch, and it would have numerous benefits to wetland health such as better nutrient capture, pollutant filtration, food production, biodiversity, and even improved resilience. [3]  Such a complex problem cannot be solved overnight, but focusing on the health of our fisheries will drive them to be more sustainable, and sustainable fisheries will keep our critical $2.4B seafood industry alive. Our coastal zone is a great asset that provides us with plentiful resources, and we have a responsibility to use those resources, such as the fisheries, in a sustainable manner. Programs like CWPPRA emphasize the benefits of sustainability on a large scale and seek to apply those practices in their restoration projects.

 

[1] http://wwf.panda.org/our_work/oceans/solutions/sustainable_fisheries/

[2] http://science.sciencemag.org/content/314/5800/787

[3] https://www.ted.com/talks/dan_barber_how_i_fell_in_love_with_a_fish?language=en

Featured image from https://e360.yale.edu/features/can-deepwater-aquaculture-avoid-the-pitfalls-of-coastal-fish-farms

 

 

Little Vermilion Bay Sediment Trapping (TV-12)

High winds and waves prevent GIWW sediments transported down the Freshwater and Schooner bayous from settling and forming the basis of vegetated marsh. This same wind and wave energy also increases shoreline erosion rates.

This project involved the construction of a series of vegetated terraces to diminish waves in Little Vermilion Bay, helping to increase sediment deposition and reduce the rate of shoreline erosion. A pattern of channels was dredged 100-feet wide and 6-feet deep to beneficially distribute sediment from the GIWW through the Freshwater and Schooner bayous. Dredged sediments were used to construct 23 earthen terraces with a combined length of 23,300 feet. After settling, the average height of the terraces was 3.5 feet above mean sea level.

The bases of the terraces were planted with 20,450 containers of smooth cordgrass (Spartina alterniflora).

The design allows commercial and recreational fisherman to access the project area, and it stimulates fishery production by creating new habitat and increasing shoreline length.

In 1998 alone (prior to the project’s completion) 40 acres of wetland habitat were created.

This project is located in the northwestern corner of Little Vermilion Bay at its intersection with the Gulf Intracoastal Waterway (GIWW) in Vermilion Parish, Louisiana. The project area encompasses 964 acres.

Monitoring is underway and preliminary observations show that the terraces are growing in width, and bay depth between terraces is decreasing indicating marsh expansion in the project area.

This project is on Priority Project List 5.

The Federal Sponsor is NOAA NMFS

The Local Sponsor is CPRA

Living Shorelines

According to NOAA, one of our managing agencies, a living shoreline is “A protected and stabilized shoreline that is made of natural materials such as plants, sand, or rock.” [1] In some situations, living shorelines are a better option than hardened shoreline protection because they have more movement of natural sediment, the ability to grow, and the obvious aesthetic value of a natural area.

‘Living shorelines’ can refer to multiple restoration techniques and coastal environments; for CWPPRA, a living shoreline can mean vegetative planting on a marsh creation cell or using a shoreline protection barrier that promotes oyster reef growth. Living restored shorelines help maintain the integrity of ecosystems, but they also provide benefits to recreation and potentially to commerce. One big push in restoration over the past few years has been artificial oyster reefs which provide wave attenuation, natural water filtration, and a harvestable population of oysters for the seafood industry. [2]

Illustration, Courtesy of NOAA [1]

Vegetated marsh provides similar benefits to artificial oyster reefs and is a tried-and-true restoration strategy. Many marsh creation projects will naturally revegetate thanks to seed banks in borrow sites but some need management to limit invasive species. In more vulnerable sites, CWPPRA actively plants native species like smooth cordgrass and California bulrush to give them an advantage against invasive populations.

CWPPRA understands that successful restoration projects, including shoreline protection, help keep ecosystems intact and productive. A changing coast means we need changing solutions, and we will strive to find better alternatives to maintain the natural environment.

[1] https://oceanservice.noaa.gov/facts/living-shoreline.html

[2] https://www.smithsonianmag.com/innovation/storms-get-bigger-oyster-reefs-can-help-protect-shorelines-180967774/

Featured image from https://oceanbites.org/oyster_reef_restoration/

 

Bayou Dupont Ridge Creation and Marsh Restoration (BA-48)

Problems: There is widespread historic and continued rapid land loss within the project site and surrounding areas resulting from subsidence, wind erosion, storms, and altered hydrology. Land loss data provided by the U.S. Geological Survey indicates that loss was occurring at a rate of 1.7% per year prior to construction. The natural limits of Bayou Dupont were difficult to determine in some areas because land loss was causing a merge of the bayou to adjacent water bodies. Natural tidal flow and drainage of patterns that once existed through the bayou were circumvented by the increasing area of open water.

Restoration Strategy: Project goals included: 1) creating and nourishing approximately 390 acres of marsh through sediment pipeline delivery from the Mississippi River; and   2) creating over two miles of ridge (10.5 acres of ridge habitat) along a portion of the southwestern shoreline of Bayou Dupont. Sediment from the river was hydraulically pumped to the project site to construct both the marsh and ridge features and additional material was dredged from Bayou Dupont to cover the ridge. The ridge is designed to mimic the configuration of other natural ridges within the watershed, and includes a constructed elevation conducive for the growth of native vegetation such as live oak, hackberry, and yaupon. The ridge is helping to redefine the limits of Bayou Dupont and reestablish the natural bank that once flanked the bayou and  protected adjacent marshes.

Location: This project is located within the Barataria Basin in Jefferson and Plaquemines Parishes. The marsh creation area is located along Bayou Dupont southeast of the waterbody known as the Pen.

Progress to Date: Construction began in the Fall of 2014 in conjunction with the Mississippi River Long Distance Sediment Pipeline Project (BA-43EB) and Bayou Dupont Sediment Delivery-Marsh Creation #3 (BA-164). Construction of the Bayou Dupont (BA-48) portion was completed in fall of 2015.

This project is on Priority Project List 17.

• Federal Sponsor: National Marine Fisheries Service (NOAA)
• Local Sponsor: Coastal Protection and Restoration Authority (CPRA)

West Belle Pass Barrier Headland Restoration (TE-52)

This headland experiences some of the highest shoreline retreat rates in the nation, measuring over 100 feet a year in some locations. As the gulf encroaches upon the shoreline, sand is removed and the headland erodes. What was once a continuous shoreline spanning several miles has been reduced to less than half its original length. Furthermore, Hurricanes Katrina and Rita removed most of the emergent headland and dunes west of the pass. This headland helps provide protection to interior marshes and the Port Fourchon area; however, its continued degradation threatens the fragile bay habitat and infrastructure it once protected.

This project will reestablish the West Belle headland by rebuilding a large portion of the beach, dune, and back barrier marsh that once existed. Approximately 9,800 feet of beach and dune will be rebuilt using nearly 2.8 million cubic yards of dredged sand, and 150 acres of marsh habitat will be rebuilt using nearly 1.4 million cubic yards of dredged material. Native vegetation will be planted upon construction to help stabilize the rebuilt marsh and dune habitat.

The project is located along the Chenier Caminada headland to the west of West Belle Pass, at the southeastern edge of Timbalier Bay in Lafourche Parish, Lousiana.

This project was approved for engineering and design in October 2006. Construction funds were approved by the Task Force in late 2009, construction began fall 2011, and construction was completed in October 2012.

This project is on Priority Project List 16.

Federal Sponsor: NOAA NMFS

Local Sponsor: CPRA

Pass Chaland to Grand Bayou Pass Barrier Shoreline Restoration (BA-35)

Reasons for Restoration:

Prior to construction, wetlands, dune, and swale habitats within the project area had undergone substantial loss due to subsidence, absolute sea-level rise, and marine- and wind induced shoreline erosion. In addition, oil and gas activities, such as pipeline construction, also contributed to the loss.

Marine processes acting on the abandoned deltaic headlands rework and redistribute previously deposited sediment. Fragmentary islands develop due to breaches in the barrier headland. Subsequently, increased tidal prism storage (the total volume of salt water that moves in and out of a bay with the tide) and storm-related impacts have led to inlet and pass formation across the newly formed islands. The Bay Joe Wise beach rim was receded and decreased to a critical width that was susceptible to breaching.

Land area in the project area had decreased from 1932 to 2000. Storms occur approximately every 8.3 years along the Barataria shoreline. Because approximately 100 feet of shoreline is eroded with each storm, shorelines of 100 feet or less are considered in imminent danger of breaching.

Restoration Strategies:

The project’s objectives were: 1) preventing the breaching of the Bay Joe Wise shoreline by increasing barrier shoreline width; 2) increasing back-barrier, emergent marsh area by some 226 acres to maintain the barrier shoreline; and 3) creating emergent marsh suitable for tidal aquatic habitats.

The Project features included a constructed beach and dune platform along approximately 2.7 miles of the gulf shoreline. Constructed landward of the beach and dune was a marsh platform with an average width of 860 feet spanning the entire project length. A water exchange channel was incorporated on the western end of the Project to facilitate flushing of Bay Joe Wise through Pass Chaland. The Project created over 420 acres requiring 2.95 million cubic yards of fill dredged from ebb shoal borrow areas. Other project features included installation of sand fencing concurrent with dune construction, dune and marsh vegetative plantings, and post-construction gapping of retention dikes.

 Above image from lacoast.gov

Location:

The project is located in the Barataria Basin, between Pass Chaland and Grand Bayou Pass in Plaquemines Parish, Louisiana.

This project is on Priority Project List (PPL) 11.

• Federal Sponsor: National Marine Fisheries Services: http://sero.nmfs.noaa.gov/
• Local Sponsor: CPRA: Coastal Protection and Restoration Authority

 

Source: 

Louisiana Coastal Wetlands Conservation and Restoration Task Force “Pass Chaland to Grand Bayou Pass Barrier Shoreline Restoration (BA-35)”. 2 March 2018, https://www.lacoast.gov/reports/gpfs/BA-35.pdf.