A Procedure for Quantifying Compensatory Debits and Credits


By: Beth Nelson, Rocky Mountain Region Administrative Assistant

Coincidental to the 10-year anniversary of the Corps/EPA Compensatory Mitigation Rule, environmental scientists Rachel Harrington and Palmer Hough conducted a study that highlighted the progress in the field of wetlands mitigation. The study, published in The Environmental Law Reporter (2019), also cites potential opportunities for improvement in the implementation of requirements in the 2008 Rule and its regulatory oversight. Harrington and Hough note performance standards were “too vague to be meaningful and enforceable and, often, the associated monitoring requirements and reporting requirements lacked the details necessary to adequately track project development and/or determine project compliance.”

Among the recommendations cited by Harrington and Hough, one fell to the Corps district level: adopting “workable, science-based crediting/debiting and service area methodologies for wetlands and streams.” The United States Army Corps of Engineers, Albuquerque and Omaha Districts, has risen to the occasion with the release of the May 2019 Colorado Mitigation Procedures, Version 1 (COMP v1) publication. The COMP provides “regulatory direction for wetland and stream mitigation; [as well as a] stream debit and credit calculator based on functional loss and improvement assessed using existing qualitative methods.”

The May 2019 COMP informs this process by providing a procedure for quantifying compensatory debits and credits, with the intent of increasing predictability and consistency.

According to the COMP publication, a wetlands debit is “a unit of measure representing the loss of aquatic functions at an impact or project site.” This is often referred to as functional loss. Credits, also known as functional lifts, are defined as “a unit of measure representing the accrual or attainment of aquatic functions at a compensatory mitigation site.”

Per the new COMP guidelines, the Colorado Stream Quantification Tool (CSQT)—used in conjunction with the CSQT workbook—generates a unitless condition score between 0 and 1 for both the existing condition of the affected property and the proposed condition of that same property. Existing and proposed scores are generated for each of four functional categories:

• Reach hydrology and hydraulics,
• Geomorphology,
• Physiochemical, and
• Biology

For further information on the new 2019 Colorado Mitigation Procedures, Version 1 (COMP v1) publication, visit the Denver Regulatory Office website (http://www.nwo.usace.army.mil/Media/Public-Notices/). The public notice is open for comments until October 11, 2019.