Version: 2.0

Published: March 29, 2023

INACTIVE: Restoration of Degraded Wetlands of the Mississippi Delta

The American Carbon Registry (ACR) methodology Restoration of Degraded Deltaic Wetlands of the Mississippi Delta v2.0 is inactive and ineligible for crediting new projects on ACR. ACR has determined that the methodology requires updates to measurement, monitoring, reporting and verification requirements to be consistent with the current version of the ACR Standard.

Methodology History

The methodology details requirements for greenhouse gas emission reduction accounting from wetland restoration activities implemented on degraded wetlands of the Mississippi Delta. The methodology quantifies increased carbon sequestration in aboveground biomass, belowground biomass, and soil organic carbon over and above the baseline scenario. Increases in CO2, methane or nitrous oxide, if significant and attributable to the project activity, must be quantified and deducted from net emission reductions.

This methodology has been revised from its original publication in order to provide equations to quantify the greenhouse gas emissions resulting from the degradation and erosion of the wetland soil horizon, specifically the top 50 cm.

The modular format provides flexibility for numerous types of wetland restoration projects including those that require hydrologic management, as well as allowing Project Proponents to select whether wetland loss will be included in the baseline. By including hydrologic management as a restoration technique the methodology addresses the broader issues of diffuse pollution and nutrient management by sustainably managing nutrient-rich waters as a resource for wetland restoration.

The methodology was developed by Dr. Sarah K. Mack of Tierra Resources LLC, with contributions from Dr. Robert R. Lane and Dr. John W. Day, and with funding from Entergy Corporation. The methodology may in the future be expanded to wetland restoration in other regions, and other wetland restoration practices.

Structure and previously approved versions

The Wetland Restoration Methodology Framework module, WR-MF, provides the generic functionality of the methodology, indicates which other modules are mandatory and optional, and contains the final calculation of Emission Reduction Tonnes (ERTs). WR-MF constitutes, together with the modules and tools it calls upon, a complete wetland restoration baseline and monitoring methodology.  An Errata and Clarification document has also been published and required for use with the current version of the methodology.

Included underneath WR-MF are:

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INACTIVE: Restoration of Degraded Wetlands of the Mississippi Delta

Version 2.0

Four baseline modules:


  • BL-WR, Estimation of baseline carbon stock changes from wetland restoration (WR)

  • BL-WR-WL, Estimation of baseline carbon stock changes from WR including projected wetland loss for the baseline scenario

  • BL-WR-HM, Estimation of baseline carbon stock changes from WR where the project activity includes hydrologic management

  • BL-WR-HM-WL, Estimation of baseline carbon stock changes from WR where the project activity includes hydrologic management as well as projected wetland loss for the baseline scenario

Two project scenario modules:


  • PS-WR, Estimation of project scenario carbon stock changes and greenhouse gas emissions from WR

  • PS-WR-HM, Estimation of project scenario carbon stock changes and greenhouse gas emissions from WR with hydrologic management

Two carbon pool modules:


  • CP-TB, Estimation of carbon stocks in above- and belowground tree biomass

  • CP-S, Estimation of carbon stocks in the soil organic carbon pool

Two emission source modules:


  • E-E, Estimation of greenhouse gas emissions

  • E-FFC-WR, Estimation of emissions from fossil fuel combustion

One miscellaneous module:


  • X-UNC-WR, Estimation of uncertainty in WR activities

In addition, the WR-MF calls upon the following pre-existing ACR-approved tools:


  • T-DEG, “Tool for the identification of degraded or degrading lands for consideration in implementing CDM A/R project activities (Version 1)”

  • T-SIG, “Tool for testing significance of GHG emissions in A/R CDM project activities (Version 1)”

  • T-RISK, “ACR Tool for Risk Analysis and Buffer Determination”

  • T-PERM, “AFOLU Non-Permanence Risk Analysis and Buffer Determination”

  • T-PLOTS, “Tool for the calculation of the number of sample plots for measurements within A/R CDM project activities”

Process documentation