Louisiana lawmakers hear scientists, advocates urging review of wetland assimilation permits

The House Committee on Natural Resources and Environment on March 18 heard scientists, conservation groups and agency staff describe evidence that Louisiana—s wastewater "wetland assimilation" projects have damaged receiving marsh and forested wetlands and called for a program review before new permits are issued.

The testimony came during consideration of House Study Request No. 7 of the 2024 session, which asks for information on "wetland assimilation projects" and how the program is working.

The issue matters because DEQ permits allow municipalities to discharge secondary- or partially treated wastewater into natural wetlands as a form of tertiary treatment. Witnesses told the committee that, at several high-loading sites including Hammond, Thibodaux and Mandeville, the receiving areas have opened to water, trees have died, and vegetation shows signs of oversaturation and accelerated decomposition.

Eugene Turner, a researcher who presented drone imagery and time-series comparisons, said the discharge has both hydrologic and chemical effects. "It has a very high ammonia content, for example, and that's toxic," Turner said, and he described areas that "turned to open water within 2 or 3 years of the assimilation material going through it." He also described a loss of root mass and rhizomes, which he said leaves marsh peat vulnerable to storms.

Rebecca Trish, executive director for Louisiana Wildlife Federation, urged a halt to new permits until DEQ completes a program evaluation. "We urge that no new permits be issued until there is a review of the program," she said, arguing natural wetlands are not hydrologically controlled like constructed treatment wetlands and therefore cannot be engineered or "cleaned out" if they become saturated.

Christy Traill, executive director of the Pontchartrain Conservancy, reviewed permit records and monitoring and identified repeated exceedances at some sites. She cited Thibodaux permit data showing fecal coliform monthly averages exceeding permit limits "79% of the time, 90% on the weekly average" in the recent record she analyzed, and she said Louisiana—s approach is looser than Florida—s, which adds biological monitoring such as benthic macroinvertebrates and fish as indicators.

Representatives of the Department of Wildlife and Fisheries told the committee their concern focused on changed habitat. Randy Myers, biologist administrator, said the department observed conversion of solid marsh to more open water and noted a "direct response from waterfowl, shorebirds," but that the change was a degradation of the original marsh habitat. Myers said the department recommended hydrologic studies and long-term monitoring to determine whether pooling or other flow changes are implicated; he also said Wildlife and Fisheries did not test for ammonia.

Department of Environmental Quality Secretary Aurelia Giacometo said DEQ will provide additional answers but noted the agency had not been given advance notice to prepare full responses for the hearing. "They are seen as something that is a waste," Giacometo said of waste streams in an analogy about creating market value for material streams; DEQ also signaled willingness to work with the committee on follow-up questions.

Kyle Balcom of the Office of Coastal Management said coastal-use permits for some of the projects date to the mid-2000s and that the office would treat any new applications differently today, and he described coastal permit conditions that can require pre- and post-project monitoring and adaptive management.

Committee members pressed for more data from DEQ and for agency follow-up. Committee members also asked about comparisons with river diversions and with engineered constructed wetlands; witnesses repeatedly emphasized that constructed wetlands are hydrologically controlled and managed, whereas the state—s natural receiving wetlands are not.

No formal action or vote was taken at the hearing. Committee members requested that DEQ return with detailed monitoring data, permit compliance records and answers about how the agency enforces the permit condition that receiving wetland productivity must not decline beyond the permit limits.

The committee indicated it will seek written follow-ups from DEQ, Wildlife and Fisheries and other agencies and may hold further hearings once the agencies provide requested documentation.