The federal and state trustees holding the purse strings for an unprecedented diversion project to help rebuild Louisiana’s disappearing coast released a report Wednesday signaling they are likely to approve the plan that will cost as much as $2.26 billion.
The project would be paid for with settlement money related to the 2010 BP Deepwater Horizon oil spill, overseen by the trustees.
The new report on the Mid-Barataria Sediment Diversion is based in part on and released in conjunction with a final environmental impact statement on the project released this week by the Army Corps of Engineers. Like the Corps report, it also details the benefits and detriments of the project that would funnel up to 75,000 cubic feet per second of water and sediment from the Mississippi River into the Barataria Basin to build new wetlands in Plaquemines and Jefferson parishes.
But unlike the Corps report, the trustees’ version is focused specifically on how the project will restore damages made by the BP oil spill in the Barataria Basin, both directly through oiling of wetlands like those along Bay Jimmy that led to their disappearance, and indirectly through impacts on fisheries, birds and other natural resources that were damaged by the spill throughout the Gulf of Mexico.
The trustee study concludes that the benefits of the diversion – the potential to add 21 square miles of new wetlands in the basin by 2070 and improve living conditions for a variety of wildlife types – more than outweigh the detrimental effects, including expected reductions in commercial fishery catches of oysters, brown shrimp and some finfish, and the death of hundreds of bottlenose dolphins due to the large-scale introduction of fresh water.
“The benefits would be significant and would primarily derive from the creation of thousands of acres of marsh that, with a steady supply of Mississippi River sediment, would be sustained over decades even in the face of rising sea levels and coastal erosion,” the report said.
The Barataria Basin will face a daunting loss of the majority of its remaining wetlands during the first 50 years of the project’s operation, due to continued subsidence and increasing levels of sea level rise. But at the end of that period, more than 20% of the basin’s remaining marsh will have been created or sustained by the diversion, and the project will remain the only way to achieve a self-sustaining marsh ecosystem in the basin, the report concluded.
State Coastal Protection and Restoration Authority officials point out that both the Corps and trustee studies are based on comparatively high estimates of sea level rise driven by global warming, and if efforts to reduce worldwide levels of greenhouse gases are successful during the project’s first 50 years, the amount of land it could generate would likely rise, and the amount of wetlands lost in the basin also would be less.
The Louisiana Trustee Implementation Group, which oversees use of $4 billion of BP natural resource money in the state, includes representatives of the federal Environmental Protection Agency, National Oceanic and Atmospheric Administration, U.S. Fish & Wildlife Service and the Natural Resources Conservation Service, and the state Coastal Protection and Restoration Authority, Department of Natural Resources, Department of Environmental Quality, Department of Wildlife and Fisheries, and the Louisiana Oil Spill Coordinator’s Office.
The diversion must still gain Corps and state approval of environmental permits, and the trustees must still confirm that the project meets the goals of the post-spill mitigation plan.
The spill damage assessment found that a combination of “marsh creation and ridge restoration plus a large-scale sediment diversion would provide the greatest level of benefits to injured wetlands, coastal, and nearshore habitats and to the large suite of injured resources that depend in their life cycle on productive and sustainable wetland habitats” in both the Barataria Basin and the broader northern Gulf of Mexico.
Wednesday’s report confirms that the project meets those requirements recommended by the trustees, but a final record of decision will not be issued until late December, in coordination with the Corps’ expected Dec. 23 decision on its permits.
The newly created marsh will benefit many fish and wildlife species in the basin, the report concluded, including red drum, largemouth bass, blue crab, white shrimp, Gulf menhaden and migratory waterfowl, which translates into benefits to recreational users, and as food sources for wildlife offshore in the Gulf of Mexico.
The trustees said they also recognize that freshening the basin with Mississippi River water will damage some natural resources, but pointed out that the damage must be weighed in the context of 100 years of change in the Barataria Basin. The basin went from being dominated by freshwater, with sediment overtopping natural levees along the river, before modern flood control levees cut off that flow. That has been accompanied by decades of wetlands loss and saltwater intrusion that have resulted in more brackish and saltwater species dominating the area.
“Reconnecting the river to the basin to restore an estuary that has been degrading and becoming more saline for almost a century will produce significant changes to current conditions in the Barataria Basin, which will negatively affect some of the species that currently reside in the basin,” the report said. “Key species that would be adversely affected include dolphins, brown shrimp, and oysters.”
The trustee report includes the state’s proposed $378 million mitigation plan and a plan for operating the diversion if it is approved.
The report also outlines how the new land created by the diversion is likely to slightly reduce hurricane storm surges along west bank levees, and how some communities south of the diversion will see more numerous high tide days and increased flooding risk when the diversion is operating.