Lawmakers hear scientific, agency and conservation concerns over wastewater assimilation in coastal wetlands

The House Committee on Natural Resources and Environment on March 18 received technical testimony and stakeholder concerns about the state’s wastewater assimilation program and its effect on coastal wetlands, including cases at Hammond, Thibodaux and Mandeville.

Committee members heard researchers and conservation groups say some receiving wetlands are converting to open water and showing signs of nutrient oversaturation, while state agencies described gaps in monitoring and coordination.

The session focused on House Study Request No. 7 (2024 session), an informational review of wetland assimilation projects. Eugene Turner, identified in the hearing as a retired faculty member and researcher, described aerial and field observations from multiple sites and said the receiving wetlands are showing rapid change. "It has a very high ammonia content, for example, and that's toxic," Turner said, and he described cases where forested wetlands opened to permanent standing water within a few years of discharge. Turner testified that in his measurements of constructed and assimilation wetlands he has repeatedly observed reduced root and rhizome development and that those changes accelerate decomposition and make marsh soils vulnerable to storms.

Rebecca Trish, executive director of the Louisiana Wildlife Federation, told the committee that the program’s stated goal — to use natural wetlands as tertiary treatment while improving coastal wetland sustainability — is not being met in some locations. "These wetlands are being relied on for treatment and not merely nutrient assimilation," Trish said, and she urged that "no new permits be issued until there is a review of the program." Trish said the program allows discharges with higher biological oxygen demand (BOD) and total suspended solids (TSS) than typical surface-water permits and noted the difficulty of removing or rehabilitating natural wetlands once they become oversaturated.

Christy Traill (executive director, Pontchartrain Conservancy) presented permit- and compliance-based analysis, citing ongoing exceedances at particular sites and contrasting Louisiana practice with other states. Traill said permit inspections and discharge-monitoring reports show recurring failures at some facilities: "At Thibodeaux you can see fecal coliform monthly average has failed 79% of the time, 90% on the weekly average," she said. Traill further noted that Florida, which also allows some discharges to wetlands, requires additional biological metrics (benthic macroinvertebrates and fish) and stricter numeric limits for assimilation sites than Louisiana’s current assimilation permits.

Representatives from the Department of Wildlife and Fisheries described site-level observations at Hammond Wildlife Management Area and said they had recommended hydrologic study and adaptive management for impacted areas. Randy Myers, biologist administrator with the Department of Wildlife and Fisheries, said the department found vegetation changes and an increase in open-water habitat, and that some wildlife – including waterfowl – had responded to the new conditions, producing a mixed set of habitat outcomes.

Kyle Balcom, administrator in the Office of Coastal Management (Department of Energy and Natural Resources), said coastal-use permits issued two decades ago were conditioned on the information then available and that current permit practice would require more upfront hydrologic analysis and monitoring. Balcom said his office would need to re-evaluate older permits if new evidence shows unauthorized clearing or impacts beyond what was permitted.

Committee members asked agency representatives whether ammonia and other constituents currently not listed in all permits are being monitored; testimony indicated ammonia monitoring is not universal across sites. Witnesses recommended a program-level review that would: (1) inventory assimilation permits and their monitoring requirements; (2) compare permit limits and compliance records; (3) evaluate vegetation and aquatic biota (plants, benthic macroinvertebrates, fish) at receiving sites against local control sites; and (4) require adaptive management or mitigation where permittees cause or fail to remedy declines in wetland productivity.

No formal votes or regulatory changes were made at the hearing. DEQ staff told the committee they would need to return with more complete responses to specific permit and compliance questions; Department of Energy and Natural Resources staff said they could follow up on earlier coastal-use findings. The committee concluded the informational hearing and moved to its next scheduled item.