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Mitigation is a way to replace wetlands and/or waters that are unavoidably affected by the construction or development of a proposed activity or project.  According to the Clean Water Act, all proposed activities and projects must make every effort to avoid or minimize impacts to wetlands, streams, lakes, rivers, etc. 

If impact avoidance and minimization can not be completely accomplished, then mitigation requirements must be considered, as outlined in the Compensatory Mitigation for Losses of Aquatic Resources Final Rule (33 CFR Part 325 and 332; 40 CFR Part 230) in April 2008.  Several forms of mitigation are available. Restoration or enhancement of degraded wetlands or waters affect by a proposed work activity is one form of mitigation.  On-site preservation and buffering of remaining wetlands or waters can also be considered mitigation. The purchase of credits from a wetland mitigation bank is another form of mitigation.  All proposed mitigation plans require approval from the U.S. Army Corps of Engineers. The Corps reviews each application package for its potential to adversely impact aquatic resources.  The Mitigation Memorandum of Agreement (MOA) between the U.S. Army Corps of Engineers and the Environmental Protection Agency (EPA) was set forth in February 1990 and provides the guidance for the 404 (b)(1) guidelines.  For projects evaluated under Section 404 of the Clean Water Act, no discharge of dredge or fill materials into waters of the United States shall be approved that does not meet the requirements of the 404(b)(1) guidelines. When developing a mitigation plan for a proposed activity or project, assistance from a qualified environmental consultant may be necessary, but is not required for the application package to be accepted and reviewed.  Contact your local Corps Field Office for further information.

Compenstory Mitigation Rule Q&A's 

RGL No. 08-03: Minimum Monitoring Requirements

Memo: Mitigation Plan Checklist 

Mitigation Plan Checklist  

Minimum Requirements for Annual Monitoring Report

Compensatory Mitigation Plans Sheet


Mitigation Banks

Mitigation Banking is a provision of the mitigation process, as outlines in the November 28, 1995, Federal Register, Vol. 60, No. 228, pg 58605-58614, Federal Guidelines for the Establishment, Use and Operation of Mitigation Banks.   

A mitigation bank is an authorized “activity” permitted under the Clean Water Act, Section 404.  Use of a mitigation bank is one option available if compensation is required for the authorized impacts of your project.  A mitigation bank established advanced credits - as impacts occur debit accrues.  Compensation is achieved by debiting from the bank. 

Approval and use of a mitigation bank is determined on a case-by-case basis.  Please verify the applicability of using a mitigation bank for your project/activity before planning its use.  Questions regarding the status of a bank, mitigation program, or a proposed mitigation program may be directed to the local Corps Regulatory Office in the county where your project is located. 


Idaho Wetland Ecosystem Services Protocol (WESP-ID)

The Wetland Ecosystem Services Protocol for Idaho (WESP-ID) is functional assessment methodology for use in Idaho. WESP-ID is a standardized method for rapidly assessing wetland functions, which can then be used to help inform project site selection alternatives, as well as the selection, design, credit determination and monitoring of compensatory wetland mitigation sites.

Click here to view the Special Public Notice regarding the WESP-ID

Click here to access the WESP-ID Manual

To obtain a copy of the accompanying Excel® spreadsheet calculator, please contact the Regulatory Division at or 208-433-4464.