The Lake Pontchartrain Basin Foundation has been active in the Lake Pontchartrain basin and southern Louisiana, improving the water quality and protecting coastal habitats for nearly 30 years. This nonprofit organization has been successful in having not only the lake, but eight additional local water bodies removed form the national Impaired Water Bodies List and making the lake and much of the basin safe again for recreational use.
Around 10 years ago, the LPBF started investigating the practice of assimilation of treated wastewater discharged into natural wetlands. In short, this is a new way of treating wastewater in Louisiana, which scientists hoped would be beneficial in increasing vegetation growth in the wetlands, reducing damaging saltwater intrusion, and providing cities with cost efficiencies. Currently 10 cities in south Louisiana are using such a system; additional municipalities are applying for permits and the City of Mandeville’s permit is going through the renewal process.
Unfortunately, hard scientific analysis has determined that assimilation fails to deliver these benefits and worse, these systems are damaging the wetlands. Three hundred acres have been lost at the Hammond Assimilation Project, and 80 acres are currently looking distressed at the Mandeville Assimilation Project. This practice of discharging treated wastewater into natural, uncontrolled marshes is not used anywhere else in the United States. The LPBF has worked with more than 50 scientists to understand assimilation. One of the main problems is the continuous discharge of nutrients and water. This overloads the wetlands ecosystem and causes high water levels. This drowns the plants, including the grasses and trees.
In addition, the treatment standards do not meet the minimum federal requirements. Some projects allow for the discharge of as much as 15 times the amount of pollutants than traditional wastewater facilities. As for inhibiting saltwater intrusion, the water flow is far too small to make any sizable difference. It may appear cheaper to discharge wastewater into natural wetlands, but at what cost?
Wetlands offer us the first line of natural defense against storms and storm surge. Is it is really economical to put our cities at greater risk? Remember we are already losing a football field of wetlands every 100 minutes, how can we do anything that might accelerate this loss? Assimilation has to stop. The facilities need to be modified and independent monitoring systemized.
Of most pressing concern is The City of Mandeville’s application to extend its permit with reduced regulation. Despite all of the reasons above, the Louisiana Department of Environmental Quality is considering this application, even though it contravenes federal environmental regulation. DEQ must deny this permit and we must work together to find better solutions for our cities and our wetlands.
executive director, Lake Ponchartrain Basin Foundation