Doctor of Philosophy (PhD)


Oceanography and Coastal Sciences

Document Type



Ecosystem response, stakeholder interactions, and the policy implications to a wetland assimilation project are reported here for the City of Mandeville, St. Tammany Parish, Louisiana. Between September 1998 and October 2004, input of secondarily treated wastewater effluent was found to have a net positive effect on the downstream wetland receiving basin. The major hydrologic inputs to the system are the effluent, precipitation, and back water flooding from Lake Pontchartrain. Nutrient levels were generally low except in the immediate vicinity of the outfall and removal efficiencies of N and P ranged from 44% to 87% and 25% to 93%, respectively. On average, TN and TP removal efficiencies were 59% and 69%, respectively, for the study period. Aboveground net primary production of the freshwater forest system was high downstream of the effluent discharge. Also downstream of the outfall, accretion rates were double the rate of relative sea level rise in the area. Re-direction of nutrient-enhanced effluents from open water bodies to wetland ecosystems may maintain plant productivity, sequester carbon, maintain coastal wetland elevations in response to sea-level rise in addition to improving overall surface water quality, reducing energy use, and increasing financial savings. Stakeholder interactions can often be as difficult to resolve as scientific questions. Further progress to improve water quality and regulate point source pollution often requires adjustment in policy strategies to enhance society's capacity to deal with more problematic issues of non-point source pollution. High cost and economic impacts on communities will propel the search for cost-effective water quality management. In addition, cooperation between the public and private sectors can build trust, consensus, and the ability to implement coastal resource projects. In this Mandeville, Louisiana, case, the use of science-driven solutions in natural resource management was successful in developing cost savings and coastal wetland preservation from the renewable ecological engineering technology of wetland wastewater assimilation. Integration of a national carbon and wetland policy may stimulate investments in energy efficiency and wetland enhancement. The next step must be the development of an annual revenue source to encourage state and private landowners to work together by providing incentive to promote wetland enhancement.



Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

John Day