Wetland Assimilation


The idea of a wetland assimilation project is to introduce treated sanitary wastewater or other approved types of wastewaters into a suitable wetland to ensure growth and health of the wetland. Natural wetland loss is a problem in Louisiana. This problem is caused, in part, by insufficient sedimentation, relative sea level rise, and land subsidence. The introduction of nutrient rich wastewater to natural wetlands is beneficial in that it stimulates productivity in the wetland. This productivity promotes vertical accretion through increased organic matter deposition and the formation of soil through increased root growth. This vertical accretion helps maintain the wetlands. Additionally, the total suspended solids, provided by the wastewater, also increase the sediment level in the wetland.

The importance and function of wetlands include, but are not limited to the following: erosion and flood control, saltwater intrusion control, water quality enhancement, habitat for threatened and endangered species, wildlife habitat, nutrient material cycling, recreation and aesthetics.

Benefits of Wetland Assimilation Projects for the Environment

  • Removes direct discharges of treated wastewater into state waterbodies
  • Can help prevent saltwater intrusion into the wetland
  • Add an abundance of needed nutrients into the wetland to stimulate plant growth
  • Carbon sequestration

Benefits For a Permittee

  • Less operations and maintenance costs
  • A “green” approach to wastewater treatment

Feasibility Study - Before a wetland assimilation project can be approved by the LDEQ, a feasibility study must be performed. The following is the information necessary to determine the feasibility for a project:

  • A delineation of the available wetland area
  • A description and suitability of the type classification of wetlands and of the vegetation of the proposed wetland areas
  • Number of acres of wetlands required for assimilation
  • A list of uses that exist within the wetland areas
  • A list of landowners of the proposed wetlands including the availability of ownership and/or easement agreements
  • A location of at least three (3) main sampling points within the wetland and one (1) reference points
  • A hydrology and a hydrograph of the proposed assimilation area with a preliminary distribution system
  • Long-term average loading rates to the wetland area

Baseline Study - Once a feasibility study has been completed and determined that the wetland assimilation will succeed, a baseline study must be performed prior to the discharge into the wetland. The baseline study will consist of the following:

  • Vegetation analysis
    • Aboveground biomass
    • Leaf litter sampling
    • Diameter measurements
    • Aboveground net primary production (NPP)
    • Marsh grass aboveground productivity (for baseline studies for marshes)
    • Understory vegetation density and basal area
    • Tree species composition
    • Nutrient and metals analysis of green leaves
  • Sediment analysis for metals and nutrients
  • Water level measurements/analysis
  • Analysis of the surface water
    • Dissolved oxygen and water temperature
    • Total dissolved solids and pH
    • Nutrients
    • Total suspended solids
    • Biological oxygen demand
    •  ICAP analysis for Mg, K, S, Na, Ca, B, P, Pb, Zn, Cr, Si, Co, Fe, Mn, Ni, Al, Cd, Cu, F, Cl, Br, NO3, NO2, PO4, and SO4
    • Fecal coliform
  • Accretion measurements

Existing and Proposed Wetland Assimilation Projects

Wetland Assimilation Project Permit Application and Annual Report Forms  

Wetland Assimilation Regulations

LAC 33:IX.1109.J

LAC 33:IX.1113.B.12.b