- Download Ecological Performance Standards for Wetland Mitigation (PDF, 3.6MB)
- Download Appendices (PDF, 1.2MB)
- Visit the EPA's Wetlands Programs website
Ecological Performance Standards for
An Approach Based on Ecological Integrity Assessments
Wetland mitigation and restoration practitioners, as well as scientists and policy makers, have been calling for stronger ecological performance standards to guide the wetland mitigation process. Here we present two methods for setting those standards: a) a watershed approach and b) ecological performance standards based on ecological integrity assessment methods.
A watershed approach can assist the process of wetland mitigation. The following criteria can be used to create an informal watershed approach.
- Landscape integrity index — integrate cumulative impacts of past development activities, focusing on ecosystems.
- Fish faunal intactness index — address cumulative impacts of past development on aquatic species.
- Locations of critically imperiled (G1) and imperiled (G2) species and rare or high-quality ecosystem types — address presence and need of sensitive species and rare wetland types.
- Ecosystem maps of the watershed — to characterize ecosystems of the watershed, including identifying wetlands that are difficult or impossible to restore, such as fens or bogs, or may have a long time to recovery, such as forested wetlands.
- Information on high priority conservation sites identified by a variety of conservation and wildlife agencies, and state and federal agencies.
Our ecological integrity assessment method for establishing performance standards for mitigation builds on the variety of existing wetland rapid assessment methods. It emphasizes metrics that are condition-based, separate from those that are stressor-based. The assessment uses the following steps.
- Develop a conceptual model with key ecological attributes and identify indicators for wetland types, at multiple classification scales (NVC formation, NatureServe ecological system, coupled with HGM and Cowardin classifications).
- Use a three-level approach to identify a suite of metrics, including Level 1 (remote sensing), Level 2 (rapid field-based), and Level 3 (intensive field-based) metrics.
- Identify ratings and thresholds for each metric based on “normal’ or “natural range of variation” benchmarks for each formation.
- Provide a scorecard matrix by which the metrics are rated and integrated into an overall assessment of the ecological integrity of the ecosystem.
- Provide tools for adapting the metrics over time as new information and methods are developed.
We provide an overview of the metrics and their ratings for the various assessment levels, as well as detailed protocols and scorecards for metrics at Level 1 and Level 2. Level 3 metrics are incomplete at this time, but we provide several examples.
The objective in setting performance standards and in conducting subsequent monitoring is to collect sufficient data to answer the hypothesis: has the mitigation wetland met the performance goal within the monitoring period? The performance standards developed above include a broad range of structural and functional measures, including hydrology, vegetation and soils, and rely on reference wetlands as a model for the dynamics of created or restored sites. We use several examples to show how ecological integrity assessments can be used to set ecological performance standards for mitigated sites, so that a more definitive answer can be given regarding the ecological success of mitigation efforts.
Our methods point towards the kinds of ecological applications that are needed for mitigation. Future studies are needed to advance these methods and test them on a variety of wetland mitigation sites.
Funding for this report was provided by a grant from the Environmental Protection Agency through Assistance Agreement #WD-83328301-01.