Gulf Restoration Network

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Scott Eustis
Healing the Marshes of the Louisiana Delta
Blog -
Friday, 20 January 2012 16:46

When you are cut, you bleed. The lacerations into the marsh carved by canals bleed our wetlands’ ability to provide for us.  Oil and gas canals, most of which only access dried up or abandoned wells, have been dredged through tens of thousands of acres of marsh in the Louisiana Delta.

These canals have cut up the marshes.  Less obvious are the marshes buried on either side of the canal by dredge spoil.  The extraction of oil and produced water from the wells has aggravated the rapid subsidence, or sinking, of the Barataria-Terrebonne basin. 

Area off the GIWW Near Mandalay NWR in Terrebonne BasThese wounds also alter water flow in and out of their surroundings, so that marshes are weakened for a mile around each spoil bank. These sick marshes are less likely to grow, or "vertically accrete," against subsidence and a rising sea level. 

The easiest way to restore our interior marshes, and allow the wounds to heal themselves, is to remove the spoil that has buried marsh for decades.  This is called "backfilling." [reference] Although the canals are never completely filled, the shallow water allows hunters and fishers access while providing a platform for underwater plants that are home to crabs and fishes.

Specifically, there is no reason that inactive canals should remain open on lands in the public trust.  We, the coastal communities, need healthy marshes for our food and shelter. Public lands should serve the public good, especially where drilling activities have been dormant for decades. 

We were wondering how large an area these spoil banks amounted to, given the large acreage of canals dredged across the Delta.  Using maps and aerial photos from USGS and other government sources, we looked for spoil banks in public marsh intact enough to heal itself.

Acreages of canal in each public parcel

Many areas, like Point Aux Chenes Wildlife Area, have seen so much impact from the industry that the potential for restoration is almost nil.  The oil and gas industry has destroyed 40% of the marshes within Point Aux Chenes Wildlife Management Area ("WMA"), and there remain only 70 acres of spoil that could, perhaps, be restored to marsh.

 

Point Aux Chenes. Backfilling might not work here.

Other areas, like Salvador and Timken WMAs, are more intact.  Marsh under these spoil banks could recover very quickly.  Although there is still oil extraction in these public areas, only about 30% of the hundreds of wells are active or “shut in” for future use.  That means about half of the canals have been inactive for decades.  The marshes along these canals are candidates for restoration. Uncovering them would give about 350 acres of direct benefit, and more over twenty years.

Spoil areas away from active oil wells in Timken WMA. (SONRIS)

There are hundreds of canals that have been left open for decades.  Every year these canals stay open, with no benefit to the companies, no benefits to the public, is a year we have lost the benefits the marsh gives us. 

GRN believes that all inactive wells, all plugged and abandoned wells and dry holes on public lands should have their access canals backfilled, or at least have their banks degraded to restore the natural flow of water across the marsh. 

We estimate that there could be more than 2000 acres of direct marsh restoration, if our preliminary assumptions hold, for interior public lands across the Delta.  This number does not include the countless miles of marsh restored to health when sheet flow of tidal waters is restored.

These scars are Louisiana's to bear. There are many more miles of privately owned wetlands that show these track marks of oil addiction. In a time when Louisiana is desperately seeking federal funding to restore marsh, our public lands cannot afford to continue to suffer from these historic abuses.

 Scott Anderson is a Healthy Waters intern for Gulf Restoration Network.  Scott Eustis is the Coastal Wetland Specialist for GRN.

Backfilled canal - Yankee Pond in Jean Lafitte National ParkBackfilled canal - Yankee Pond in Jean Lafitte National Park. the marsh on either side has begun to recover, and the golden meadow is again visible as a vista.

 

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