Barrier Shoreline Restoration

The Barrier Shoreline Restoration aspect of the Louisiana Coastal Area, Louisiana – Ecosystem Restoration: Barrier Island Restoration, Marsh Creation, and River Diversion, Barataria Basin Feasibility Study, is investigating the restoration of the barrier islands and barrier shorelines in the Barataria Basin in Louisiana. 

Purpose:
The overarching goal of the Coast 2050 Plan is to sustain a coastal ecosystem that supports and protects the environment, economy, and culture of southern Louisiana, and contributes greatly to the economy and well being of the nation. The purpose of the Coast 2050 strategies for the Barataria Basin is to restore and/or protect the natural and human environment to create a sustainable ecosystem in the Barataria Basin within the context of the Gulf of Mexico ecosystem, including coastal Louisiana. This aspect of the study investigates barrier shoreline strategy R2-22 of the Coast 2050 Plan for the Barataria Basin. The purpose of this investigation is to develop projects to provide and sustain the typical ecological attributes (unique arrangement of habitats including shallow intertidal zone, beach, dunes, back marsh, bays, and passes) of the barrier islands, headlands, and shoreline in the Barataria Basin.

Action Area:
The barrier shoreline system in Barataria Basin begins about 72 km (45 miles) northwest of the mouth of the Mississippi River (Southwest Pass) and forms a concave arch with respect to the Gulf of Mexico at the southern end of the Barataria Basin. Barrier islands, headlands, and shoreline offer unique ecological characteristics with an array of intertidal bottoms, beaches, dunes, shrub thickets, maritime forests, and salt marshes not present in interior wetlands. The assemblage of plants and animals is different than can be found in any other area of the basin or in Louisiana. Some of the species are endemic to barrier areas. A variety of seabirds, wading birds, and shore birds such as black skimmer, reddish egret, piping plover, and least tern utilize barrier islands. The islands serve as resting areas for migrating birds, nesting locations for birds such as brown pelican, and possible nesting beaches for sea turtles, as well as providing unique habitats for many fish species.

The barrier shoreline in Barataria Basin from Bayou Lafourche to Sandy Point has undergone significant movement and reduction in size during the past 100 years. While some lateral movement of the shoreline is expected as sand is reworked in the nearshore environment, the shoreline has retreated rapidly. Tidal passes that have opened in the islands during the passage of storms have not resealed in fair weather. Increase of the tidal prism of Barataria Bay, which has occurred as a result of wetland losses in the Barataria Basin, has amplified the barrier shoreline loss rate. Islands have diminished in size (narrowed) to the point that they are likely to vanish in the near future. For example, it is predicted that Grand Terre Island may be gone by 2008 (Reed et al. 1995). Overall, the Barataria barrier islands decreased in area by 47 percent from the 1890s to 1988.

The Caminada-Moreau Headland, forming the western portion of the Barataria barrier system, has experienced some of the highest rates of shoreline movement on the Louisiana or Gulf coast. Between 1978 and 1988, the coast retreated at a rate of 13.6 meters/year (45 ft/yr). The shoreline has retreated over 1.6 km (1 mile) in some locations from 1887-1988 (Williams et al. 1992). The Plaquemines Barrier System in the eastern portion of the system retreated at an average rate of 5.5 meters/year (18 ft/yr) from 1884-1988. In 1884, Grand Terre Island was 1,699 hectares (4,193 acres) with an average width of 909 meters (2,982 ft), but by 1988, it was only 513 hectares (1,266 acres) with an average width of 530 meters (1,739 ft). In 1884, Shell Island was 127 hectares (313 acres) with a width of 136 meters (446 ft). In 1988, it was 69 hectares (170 acres) and 105 meters (345 ft) in width (Williams et al. 1992). The shoreline has retreated 0.8 to 1.2 km (0.5-0.75 miles) over a large part of the Plaquemines Barrier System.

Many of the barrier shoreline areas in Barataria Basin have become nothing more than fragmented, low mounds of sand, easily washed over by minor storm events, and provide poorer habitat than fully developed barrier islands. As the barrier shorelines become narrower and disintegrate, bays and wetlands behind them become more directly connected with the Gulf of Mexico. This exposes the more fragile landscape features to higher wave action and higher salinity water.

The study area is located in Lafourche, Jefferson, and Plaquemines parishes, and includes the barrier shorelines, barrier islands, passes, and back marshes from Belle Pass on the west to Sandy Point on the east. In addition to creating valuable habitat for wading birds, waterfowl, fishes, migratory neotropical songbirds, shrimp, crabs, and other organisms, the proposed action provides other advantages: 

1.   The proposed alternatives potentially provide a low risk and quickly implementable plan to address coastal land loss in the Barataria Basin;

2.   The proposed alternatives are strategically placed in the study area and could potentially yield benefits to other coastal resources within the unique Barataria Basin ecosystem, and the human infrastructure associated with transportation, oil and gas extraction, utilities, etc.;  

3.   The proposed alternatives could be implemented independently of the remaining Coast 2050 Plan strategies for the Barataria Basin.

During the Coast 2050 public meetings conducted in 1998, Strategy R2-22 – Restore/Maintain Barrier Headlands, Islands, and Shorelines, was considered a viable ecosystem restoration strategy. Hence, this strategy will be developed into alternatives for the potential action. Other alternatives that will be considered include the No Action Alternative, alternatives presented in the Barrier Shoreline Feasibility Study, and alternatives developed during the scoping process. Alternative plans developed will investigate sand nourishment, dune restoration, beach restoration, back marsh restoration, shoreline stabilization, vegetative planting, or combinations thereof. 

Barrier shoreline restoration design features will be evaluated to ensure compliance with current Federal and State laws and regulations. Any adverse effects of the alternative plans will be identified and appropriate mitigation measures will be included in the plans. However, because the proposed action is ecosystem restoration, it is not the intent to generate alternative plans that would require mitigation. An Environmental Impact Statement (EIS) will be prepared during the feasibility phase because of the potential for significant direct and indirect, secondary, and cumulative impacts on the human and natural environment. 

References:
Reed, D.J., E.M. Swenson, and J.G. Gosselink. 1995. Physical Setting. D.J. Reed (ed.) pp. 9-23. In: Status and Trends of Hydrological Modification, Reduction in Sediment Availability, and Habitat Loss/Modification in the Barataria-Terrebonne Estuarine System. BTNEP No. 20. Barataria Terrebonne National Estuary Program, Thibodaux, LA. 

Williams, S.J., S. Penland, A.H. Sallenger, Jr. (eds.) 1992. Atlas of shoreline changes in Louisiana from 1853-1989. U.S. Geological Survey, Reston, VA. 

Barrier Shoreline Restoration Notice of Intent - Federal Register: April 28, 2000 (text)

Barrier Shoreline Restoration Notice of Intent - Federal Register: April 28, 2000 (PDF 138 KB)

Barrier Shoreline Scoping Report (PDF 1.31 MB)