Enhancement of Barrier Island Vegetation Demonstration (TE-53)

Barrier Islands provide critical habitat and are the first line of defense to not only day-to-day coastal erosion but also to the destructive forces of major storm events. There remains a critical need to develop cost-effective improvements to existing restoration methodologies that will enhance the successful establishment and spread of vegetation in these important restoration projects. Developing methodologies to enhance vegetation establishment and growth in barrier island restoration projects is important in this very stressful environment because healthy vegetative cover traps, binds, and stabilizes sand and sediment, thereby improving island integrity during storm and overwash events.

The purpose of this demonstration project was to test several technologies and/or products to enhance the cost-effective establishment and growth of key barrier island and salt marsh vegetation. Humic acid and broadcast fertilization regimes were applied. The humic acid amendment and broadcast fertilization regime techniques are intended to “jump start” and facilitate the rapid establishment and expansion of vegetation. Humic acid benefits were demonstrated in both intertidal and supratidal plantings, whereas broadcast fertilization benefits were only demonstrated in supratidal plantings.

Each product (humic acid and fertilizer) is commercially available and off-the-shelf. Enhancing the establishment of woody vegetation (black mangrove and groundsel bush) was achieved via high-density dispersal techniques of propagules and seeds, a cost-saving alternative to planting container-grown transplants. All treatment test sections and reference planting areas were visually inspected and sampled quarterly (plant and soil variables) and compared to the reference area in order to develop recommendations for future planting projects.

This project involved greenhouse studies and the testing of technologies at two previously planted CWPPRA project sites. The CWPPRA projects involved were New Cut Dune and Marsh Restoration (TE-37) and Whiskey Island Back Barrier Marsh Creation (TE-50). Both sites are located in Terrebonne Parish in the Isles Dernieres Barrier Island area.

 

The project has been completed.

This project is on Priority Project List 16.

The Federal Sponsor is EPA

The Local Sponsor is CPRA

Little Lake Shoreline Protection/Dedicated Dredging Near Round Lake (BA-37)

The Little Lake mapping unit has high wetland loss caused by shoreline erosion, subsidence, and channel construction. The project is located in an area protecting approximately 3,000 acres of fragile interior marshes between the Little Lake shoreline and Bayou L’Ours Ridge. Project area wetlands are subject to high shoreline erosion rates (20 to 40 feet per year) and subsidence deteriorating interior marshes. Without construction, the project area marsh was expected to convert to mainly open water over the next 20 years.

The project’s goals were to:
1) prevent erosion along roughly 4 miles of Little Lake shoreline;
2) create 488 acres of intertidal wetlands along the Little Lake shoreline;
3) nourish and maintain 532 acres of intermediate marsh; and
4) reduce land loss rates by 50 percent over the 20-year life of the project.

The project consists of two major features, a shoreline protection structure and a marsh creation and nourishment area. The 25,976 ft foreshore rock dike was constructed by placing rocks on top of a geotextile foundation. The dike was constructed using three lifts and include gaps every 1,000 to 1,500 ft for fisheries access.

The marsh creation and nourishment phase of this project consisted of containment dikes, marsh creation in open water areas, and marsh nourishment over existing marsh. Approximately, 920 acres of marsh were created and nourished through placement of 3,165,121 cubic yards of sediment from Little Lake. The marsh creation area was planted with 17,000 Spartina alterniflora (smooth cordgrass) plugs.

The project is located in the central Barataria Basin in Lafourche Parish, Louisiana. The project area is bounded by the East and West Forks of Bayou L’Ours and the southern shoreline of Little Lake from Plum Point westward to Breton Canal.

This project was selected for Phase I (engineering and design) funding at the January 2002 Task Force meeting and for Phase II (construction) funding in November 2003. Construction was completed in 2007.

The project is listed on Priority Project List 11.