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.
CWPPRA projects are constructed within 5-7 years from initiating engineering and design.
CWPPRA projects are built in a series of phases. The first in the series of phases is Phase Zero which includes conceptual project development. Once a project is approved through the CWPPRA selection process, the project undergoes two subsequent phases to completion. Following the initial phase is Phase One where a combination of pre-construction data collection and engineering and design is incorporated. Lastly, Phase Two encompasses construction, project management, construction supervision and inspection, and operations, maintenance, and monitoring or OM&M. CWPPRA serves as the foundation for the development of restoration science and identification of project needs that have become the platform for other restoration funding programs. Over 25 years, the Coastal Wetlands Planning, Protection, and Restoration Act has authorized 210 projects, benefiting approximately 100,000 acres.
For 25 years, the Coastal Wetlands Planning, Protection, and Restoration Act has provided the only joint Federal/State coastal restoration effort with a predictable and recurring funding stream designed to restore the vanishing wetlands of coastal Louisiana. The CWPPRA program continues to pursue a full slate of coastal restoration activities, and its progress and experience provide the foundation for restoration supported by one-time funding from various other sources. CWPPRA represents a collaborative effort and is managed by a Task Force comprised of five federal agencies and the State of Louisiana. CWPPRA’s Managing Agencies include:
On October 15, the U.S. Fish and Wildlife Service hosted the 19th Annual Wild Things Festival at the Southeast Louisiana Refuge Headquarters in Lacombe, La. This exciting family-friendly event gives the community an opportunity to engage in outdoor activities while celebrating National Wildlife Refuge Week. This free public event included canoe and pontoon boat tours, hayrides, live animals, wildflower walks, kids activities, bird house building, live music, and a youth wildlife art competition.
The Coastal Wetlands Planning, Protection, and Restoration Act Public Outreach staff was among the 40 exhibitors providing hands-on activities to encourage knowledge of the Louisiana outdoors. In order to accurately portray the importance of aquatic, coastal regions, the CWPPRA staff utilized an ocean character, Sid the Restoration Squid, whose six unique legs each represented a different restoration method. The six restoration methods include barrier island restorations, marsh creations, shoreline protection, hydrologic restoration, freshwater and sediment diversions, and terracing. Each leg consisted of a distinct craft material that would correspond with a restoration method, in which children would assemble and personalize their own squid. Each child’s personal squid was accompanied by an explanation guide of CWPPRA’s efforts to restore, protect, and/or create Louisiana’s wetlands.
According to USGS-land loss analysis, much of the southern and western shorelines of Lake Lery and the surrounding wetlands were heavily damaged in 2005 by Hurricane Katrina. In the years following this storm, wind induced waves within the lake have begun to cause further damage to the lake’s shorelines. Currently the shorelines have become so damaged that the interior emergent marshes that are still intact are being exposed to the damaging waves. This has caused an increased loss of emergent marsh habitat. Even with the benefits of the Caernarvon Diversion Structure, without some type of restoration in this area, these marshes may not be able to fully recover.
This is a marsh creation and shoreline restoration project. The marsh creation aspect of the project would utilize a hydraulic dredge to extract material form Lake Lery water bottoms and pump that material into contained marsh creation cells which are located south of Lake Lery. This will initially create and/or nourish approximately 496 acres of marsh (356 Net Acres at Target Year 20). The shoreline restoration project component would have a barge-mounted dragline excavating material from the bottom of Lake Lery and placing that material along 35,831 ft. of the southern and western Lake Lery shorelines. This restored shoreline would have a 50 foot crown width and be built to a height considered high intertidal marsh.
The lake side shoreline would have a 5:1 side slope which would be planted with smooth cordgrass and bullwhip. This would initially create 55 acres of marsh (50 Net Acres at Target Year 20) along the Lake Lery shoreline. Total created/restored marsh acreage for this project is 551 acres (406 Total Net Acres at Target Year 20).
The project area is located in Region 2, within the Breton Sound Basin portion of Plaquemines Parish. The project is specifically located south of the Caernarvon Freshwater Diversion Structure and west of the town of Delacroix, southeast of New Orleans.
As of April 2016, this project is under construction with most of the lake shoreline restoration nearly completed on the southern shoreline. The western shoreline restoration feature is currently underway. There is one marsh creation cell that is nearly completed. A larger dredge will be arriving soon and marsh creation will accelerate. This project is on Priority Project List (PPL) 17.
The South Lake Lery Shoreline and Marsh Restoration project sponsors include:
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.
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.