Debate grows over using treated sewage to restore Louisiana’s vanishing wetlands
A scientific rift over wetland restoration methods has turned political in Louisiana, where critics and supporters of using treated sewage to combat coastal erosion are clashing in the statehouse.
Wesley Muller and Elise Plunk report for Louisiana Illuminator.
In short:
- Louisiana scientists and environmental groups are divided on whether using treated sewage in natural wetlands helps or harms the landscape, with some calling for a halt to these projects.
- At a recent legislative hearing, opponents of the South Slough Assimilation Wetland project argued the nutrient-rich wastewater weakens wetland soils and accelerates degradation, while no defenders of the project were invited to testify.
- While some sites have shown increased vegetation, critics question the reliability of using natural wetlands rather than engineered systems for wastewater disposal and wetland restoration.
Key quote:
“It’s happened twice, and it’s undemocratic. They never alert the larger scientific community that’s interested in this.”
— John Day, wetlands ecologist and founder of Comite Resources
Why this matters:
Louisiana’s wetlands are a frontline defense against hurricanes, a vital habitat for wildlife, and a globally significant carbon sink. But they’re disappearing fast, eroded by sea-level rise, levee construction, canal dredging, and climate change. One proposal to help restore them involves pumping treated sewage into degraded wetlands to rebuild soil and nourish plant growth. This practice, known as wetland assimilation, has stirred heated debate. Supporters say it’s a cost-effective way to slow erosion and make use of wastewater; critics warn that nutrient overload can backfire, weakening the very ecosystems it aims to save. As the Gulf encroaches and the Mississippi River’s sediment is locked behind levees, finding effective, science-backed restoration methods grows more urgent.
Read more: Louisiana's coastal wetlands face critical threat from rising sea levels
