Marsh Creation, Restoration, and Mitigation

Habitat Type
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Marsh restoration using material dredged from the Calcasieu Ship Channel and linear terrace construction are current restoration methods used on the refuge. The basic principle behind both practices is to restore habitat lost when areas have converted from emergent marsh to open water.  Shoreline protection is an important technique that is intended to prevent shoreline so marshes are protected and not lost as well.

Dredge Material

The Calcasieu Ship Channel that borders Sabine Refuge to the east is dredged on a two-year cycle to allow for large ship passage to the Port of Lake Charles. Sabine was chosen for a demonstration site to use dredged material to restore marsh that had been lost. This use of dredge material allows managers to not only restore these marshes, but to connect the restored sites with the greater landscape, restoring hydrology, and improving habitat quality and diversity. To address concerns about dredge material contaminants, the U.S. Army Corps of Engineers (ACE) analyzes soil samples along the channel prior to using the material on the Refuge.

Through partnering with U.S. Corps of Engineers (COE), National Oceanic and Atmospheric Administration (NOAA), Louisiana Department of Natural Resources (LA DNR), Coastal Protection Restoration Authority (CPRA), and our Ecological Services office, the U.S. Fish and Wildlife Service Refuge staff has restored 3,200 acres of marsh on Sabine National Wildlife Refuge since 1993. An additional 600 acres is being planned.

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The picture on top is from February 1998 while the picture on the bottom is from December 2010, showing just how much has changed within only 12 years.

Earthen Terraces

In 1990, 'checker board' terraces were constructed in ponds along Calcasieu Lake in the West Cove Unit. These were followed in 2001 by the construction of 18,000 linear feet of planted, earthen terraces in Units 6 and 7 to mitigate for impacts due to oil and gas activities. The ACE and the Louisiana Department of Natural Resources (LDNR) require compensatory mitigation for acreage loss due to dredge and fill activities in wetlands. Terraces are discontinuous low ridges constructed with bottom sediments excavated from adjacent pond bottoms. They are designed to reduce wind related wave intensity, slow water movement allowing fine sediments to settle within the area, provide favorable conditions for submerged aquatic vegetation (SAV) establishment, and increase abundance and habitat of fish and other aquatic species.

Ideal sites for terrace construction are areas where water bodies join or are threatening to join with another water body. No significant benefit to SAV has been found in two studies conducted on terraces at the refuge, but research on other terrace configurations is ongoing. An unexpected secondary benefit is they have provided nesting habitat for seabirds such as least terns, forester's terns, and black skimmers. Another secondary benefit is that terraces contribute to increased fish habitat quality as compared to sparsely vegetated open ponds. Terrace construction for 2002 exceeded 40,000 linear feet in Unit 6.

Living Reef Shoreline Protection Barrier

The U.S. Fish and Wildlife Service is partnering with The Nature Conservancy (TNC), Coastal Protection Restoration Authority (CPRA), Shell, Chevron, Citgo, and  the National Fish and Wildlife Foundation (NFWF) to complete a living reef shoreline protection project for Sabine NWR’s eastern border within the West Cove of Calcasieu Lake just east of Highway 27.   This project will use live propagating oysters to create a reef which will protect an eroding shoreline, which in turn will protect adjacent marshes,  and preserve Highway 27 which serves as a hurricane evacuation route for lower Cameron Parish.

Facts About Marsh Creation, Restoration, and Mitigation

  • Over 3,200 acres of marsh restored since 1993
  • Allows new marsh to replace lost habitat