Mitigation Credits Ratio/Wrap Methodology

Mitigation Credits Ratio/Wrap Methodology

How do I assess how many mitigation credits I need with a RATIO methodology from a mitigation bank?

Prior to 2005; mitigation banks were permitted with RATIO credits from the 5 Water Management Districts and the Florida Department of Environmental Protection; and E-WRAP, M-WRAP or WRAP Credits from the U.S. Army Corps of Engineers. Therefore, these mitigation banks that were permitted from 1996-2004 are assessed via RATIO; and are considered grandfathered in.

Therefore, some of the new environmental consultants are unaware of how to apply RATIO credits. In 2005, the Florida Department of Environmental Protection and U.S. Army Corps of Engineers changed their policy to convert mitigation credits to UMAM to provide more objective factors; and to make it less subjective.

Depending on the quality (chart below) and acreage/square feet to be impacted will determine if you need a 1:1; 1:5; or 1:2 mitigation credit per acre.. An analysis will be performed by an environmental consultant to seek if the condition of the wetland to be disturbed is insufficient, has minimal level of support, less than optional, or fully supports wetland & surface water functions.


RATIO/WRAP, Acreage of Impact x Quality (1-2 credits/acre of impact)

Low Quality: 1:1

Average Quality: 1:1.5

High Quality: 1:2


Therefore, if you have a low-quality wetland impact, you will need to purchase 1 RATIO credit per acre of impact.

If you have an average-quality wetland impact, you will need to purchase 1.5 RATIO credits per acre of impact.

If you have a high-quality wetland impact, you will need to purchase 2 RATIO credits per acre of impact.

Converting UMAM to WRAP/RATIO (Acreage):


0-0.4 FLU = 1:1

0.5-0.7 FLU = 1.5:1

0.8-1.0 FLU = 2:1


First Step is to get in touch with a wetland environmental consultant to do a wetland delineation per your site plans and score the wetlands via RATIO and/or WRAP. This will give us the accurate number of credits needed for the proposed wetland disturbance.

Second Step is to have the same wetland environmental consultant to help you submit an application with the WMD and/or FDEP, which will have the conditions of the required mitigation to offset the proposed impact. Once the mitigation credits are paid in full and the necessary permits are issued for your Environmental Resource Permit (State) and/or Clean Water Act Section 404 Permit (Federal) then you can move forward with your project!

Case Example 

Mitigation Credits are $35,000.00/Credit

Low Quality Wetland : $35,000.00/acre of impact (1:1)

Average Quality Wetland $52,500.00/acre of impact (1.5:1)

High Quality Wetland $70,000.00/acre of impact (2:1)

You can see the dramatic difference in the financial recourse regarding the quality of the wetland/surface water functions that will be adversely disturbed. Therefore, it was vital to have this quality assessed from an environmental consultant to understand if the wetland on your property is considered: LOW, AVERAGE OR HIGH QUALITY; which is a condition of understanding if it’s an optimal, minimal or insufficient to support wetland/surface water functions.