Wetland Assimilation: Climate Change Adaptation and Restoration in the Mississippi Delta

The effects of Hurricane Katrina remain indicative of the vulnerabilities of people, infrastructure, and environments to global climate change. For the Sewerage and Water Board of New Orleans (S&WB), the 2005 hurricane season resulted in widespread devastation of the sewerage, water, and drainage infrastructure. Restoration began immediately as the most massive utility recovery project in American history. During this process, the realization emerged that the sustainability of the region is dependent on the natural environment and addressing the multitude of issues that contributed to the degradation and the region's vulnerability. Therefore, a comprehensive systems analysis approach to water resource management has been developed to address the restoration of wastewater infrastructure through a wetland assimilation project, which also incorporates the societal needs of safety, economic development, environmental stewardship, and wetland restoration.This paper discusses the planned implementation of the largest wetland assimilation system in the world developed through a partnership between S&WB and St. Bernard Parish Government (SBPG). The project will utilize natural wetlands to assimilate over 100 million gallons a day (MGD) of secondarily treated, disinfected municipal effluent to restore approximately 30,000 acres of critical cypress wetlands. Currently nutrient rich effluent from both parishes is discharged to the Mississippi River where it contributes to the hypoxia, or 5000 square mile “dead zone” in the Northern Gulf of Mexico. Rerouting the effluent will allow the nutrients to be used to replenish the wetlands, rather than increasing damage to the coastal environment. Furthermore, it was proven during Hurricane Katrina that wetlands dissipate surge and wave energies thereby protecting levees from breeching and failure. An additional climate change benefit of wetland assimilation is large amounts of carbon are sequestered through biosequestration and burial. The carbon sequestration potential of the 30,000 acres is almost 1 million tons of CO2 a year, the equivalent of approximately the yearly output of CO2 of 150,000 automobiles. Therefore, wetland restoration is also an important climate change adaptation measure for combating CO2 emissions, increased tropical storms, and relative sea level rise (RSLR).Using natural wetlands for tertiary treatment is a multi-benefit climate change adaptation measure. The wetland assimilation project will integrate sustainability with mitigation measures by utilizing natural energies and sequestering large amounts of carbon. The enhanced wetlands will help protect Orleans and St. Bernard Parishes from future storm vulnerability, while the environmental improvement will enhance the local economy and culture that is dependent on productive wetlands. Importantly, the project establishes a multi-disciplinary, multi-stakeholder paradigm for infrastructure and wetland restoration, as an international model of recovery, sustainability, hazard mitigation, and climate change adaptation.