Environmental Review Toolkit
Water, Wetlands, and Wildlife

Establishment and Maintenance of Compensatory Mitigation Projects

The US Army Corps of Engineers (Corps) recently issued a new Regulatory Guidance Letter (RGL) on the Establishment and Maintenance of Compensatory Mitigation Projects under Section 404 and Section 10 of the Rivers and Harbors Act. The RGL was issued partly in response to the National Academy of Sciences report, Compensating for Wetlands Losses Under the Clean Water Act, released in June 2001. This report strongly criticized the Corps level of oversight on compensatory mitigation, particularly long-term protection, management, and monitoring. Likely as a result, some Corps field offices have been requiring additional commitments on long-term site management and monitoring. The RGL provides some guidance and insight about what State Departments of Transportation (DOT) should expect as mitigation conditions, and how the Federal Highway Administration (FHWA) can help implement reasonable measures. Following are some key points in the RGL.

  • The RGL adopts the use of the terms credit and debit for units of impact and mitigation in place of using simply area. This indicates a trend from area-based mitigation to functionally based mitigation. This will undoubtedly lead to some confusion and conflict about how impacts and compensation are assessed, and may likely result in a new emphasis on the Hydrogeomorphic Methodology (HGM) for wetland impact assessment.
  • A regional approach is emphasized for wetland resource management, including mitigation requirements. Preservation is allowed as a sole means of compensatory mitigation when it protects regionally important wetlands or other aquatic resources that are under immediate threat of loss or degradation.
  • The recent Nationwide Permit guidance emphasizes importance of buffer zones in protecting aquatic resources. Buffers are usually upland areas adjacent to wetlands, streams, or lakes that prevent degradation of water quality or provide habitat support for water-dependent organisms. The RGL recommends buffer widths of up to 50 feet wide as being reasonable for protection of aquatic resources. We agree that buffers of this width are reasonable in most cases. However, there may be special cases where greater widths may be justified. Division offices should seek assistance from the Resource Centers or Headquarters to determine reasonable buffer widths if a request for widths greatly exceeding 50 feet becomes an issue, particularly if Corps field offices consistently try to require these greater widths on all projects involving mitigation work.
  • Mitigation ratios must be based on identifiable rationales, including temporal loss and likelihood of success. The Corps defines such rationales very broadly. The FHWA and DOTs should reasonably guarantee success, assuming performance requirements have been properly established.
  • Off-site mitigation may be preferred when greater resource values can be obtained. A combination of off-site and on-site measures may occur when water quality protection requires the construction of storm water ponds on the project.
  • Mitigation sites should be permanently protected for their intended use by appropriate real estate instruments, such as conservation easements, deed restrictions, in-fee acquisition, and ownership, potentially transferred to a resource agency or organization. The transfer of mitigation sites to resource agencies or private non-profit concerns without reimbursement of federal-aid highway funds may occur if the transfer is in the public interest and is approved by FHWA. However, many DOTs are reluctant or unable by State law to transfer title to non-profits or private organizations without reimbursement.
  • The permittee is responsible for monitoring to ensure mitigation project success and identify required remedial actions at the site. This will normally be a period of from 5 to 10 years. FHWA policy is that monitoring for a reasonable length of time is eligible for Federal-aid funds. Five to 10 years is a reasonable monitoring period. Monitoring periods exceeding 5 years should be specifically justified.
  • Permittees are responsible for funding long-term management and protection of mitigation sites. The Corps will determine the need for remediation on mitigation sites. FHWA policy is that management activities necessary for successful establishment of the mitigation site are eligible activities, however, long-term continuous management past the period of establishment is not eligible. Generally, remediation of site failures is an eligible cost.

Questions and feedback should be directed to Mike Ruth (Mike.Ruth@dot.gov, 202-366-9509).

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