Restoring Louisiana Marshes: Protecting Sacred Sites, Increasing Tribal Resilience, and Reducing Flood Risk
The Lowlander Center is thrilled to embark on a new marsh restoration project, supported by the National Estuary Program and the National Fish and Wildlife Foundation and in collaboration with the Pointe au Chien Indian Tribe, the Grand Caillou/Dulac Tribe, the Grand Bayou Atakapa-Ishak/Chawasha Tribe.
Overview
Rosina Phillippe, an Elder of the Atakapa-Ishak/Chawasha Tribe and Danny Phillips.
The southeast coast of Louisiana is home to many Indigenous nations. This land is critical to the state’s protection from the worsening effects of climate change, such as extreme weather events and sea level rise.
Over the past century, extractive energy industries have dug more than 35,000 canals in southeast Louisiana, resulting in 10,000 miles of disrupted wetlands. More than three-fourths of these canals are no longer in use; however, they were not filled back in.
Canals in Southeastern Louisiana, as seen on Google Maps.
The abandoned canals have resulted in extreme land loss, as pictured to the right. The initial dredging of the canals converted 16 percent of the Louisiana wetlands to open water, but today the network of canals created by the oil and gas industry is ranked among the primary causes of coastal land loss by the United States Geological Survey.
The canals create straight avenues allowing surging ocean waters to bypass the winding bayous and barrel inland during severe weather. The weakened marsh ecosystems leave local communities more vulnerable to flooding: for many, this is a life-and-death situation.
Land loss in Southeast Louisiana, 1932-2011. Approximately 4.6 hectare of land is lost per 1 hectare of canal. (NOAA)
For Indigenous coastal communities, land loss poses a series of unique threats. Sacred sites, such as burial sites may soon be eroded. Traditional ways of life, such as shrimping, fishing, and subsistence farming, are becoming increasingly unsustainable. If marsh ecosystems are not restored soon, many tribal members will be forced to leave their ancestral lands.
Fortunately, there is an inexpensive and effective solution: backfilling canals. Backfilling involves pushing the material dug up to form the canal back into the canal. Over time, backfilled canals restore marsh ecosystems and prevent future wetland loss.
In collaboration with the Pointe au Chien Indian Tribe, the Grand Caillou/Dulac Tribe, the Grand Bayou Atakapa-Ishak/Chawasha Tribe, we are currently working to identify canals that threaten sacred places, and will prioritize these canals for backfilling.
This project not only restores wetland ecosystems, but simultaneously results in lowered flood risk and the preservation of sacred sites and traditional livelihoods.
Frequently Asked Questions
Why are the canals in coastal Louisiana important?
The difference between a backfilled canal and unbackfilled canal. (Turner & McClenachan 2018)
Over the past hundred years, more than 35,000 canals were dug by oil and gas companies in coastal Louisiana. 27,000 of these man-made canals are not used any more and were never filled back in. This has led to issues such as land loss and salt water intrusion. As Louisiana loses marshland, communities also lose protection from storms and are more likely to flood. This is a life-and-death issue for many Louisiana communities.
What does it mean to backfill a canal?
In the past when canals were created, the material dug up to let in water was placed on the sides of the canal. These mounds are also called ‘spoil banks.’ Backfilling a canal means removing those spoil banks and replacing that material back into the canal.
How will backfilling canals impact coastal communities?
Backfilling the canals will slow land loss, build land, and help to protect communities from storms. Refilling the canals will also protect oyster, shrimp, and crab habitat.
Have canals been successfully backfilled in the past?
Yes, 33 canals have been backfilled over the past 35 years. These canals prove that backfilling is a successful method of strengthening the marshes.
Two canals in 1998 prior to backfilling and 3 years post backfilling in 2005. The spoil banks are visible in the 1998 image, and the decrease in width of the open water portions of the canal is evident in the 2005 image. (Baustian et al. 2009)
A pond adjacent to the canal converts to marsh after backfilling. The arrows point to the same area in all photos. (Baustian & Turner 2006)
Additional Resources
Restoration Success of Backfilling Canals in Coastal Louisiana Marshes
Baustian, J.J. and Eugene Turner, R. (2006), Restoration Success of Backfilling Canals in Coastal Louisiana Marshes. Restoration Ecology, 14: 636-644. https://doi.org/10.1111/j.1526-100X.2006.00175.x
Restoration of dredged canals in wetlands: a comparison of methods
Baustian, J.J., Turner, R.E., Walters, N.F. et al. Restoration of dredged canals in wetlands: a comparison of methods. Wetlands Ecol Manage 17, 445–453 (2009). https://doi.org/10.1007/s11273-008-9122-6
Reversing wetland death from 35,000 cuts: Opportunities to restore Louisiana’s dredged canals
Turner R. E., McClenachan G. (2018) Reversing wetland death from 35,000 cuts: Opportunities to restore Louisiana’s dredged canals. PLOS ONE 13(12): e0207717. https://doi.org/10.1371/journal.pone.0207717
The Life and Death and Consequences of Canals and Spoil Banks in Salt Marshes
Turner, R.E., Swenson, E.M. The Life and Death and Consequences of Canals and Spoil Banks in Salt Marshes. Wetlands 40, 1957–1965 (2020). https://doi.org/10.1007/s13157-020-01354-w
Exploring a backfilled canal in Southeastern Louisiana. (Healthy Gulf)
Header image copyright Healthy Gulf