MDT Montana Wetland Field Evaluation Form and Instructions 



July 1. 1996 



conditions with predicted post-project conditions. This concept is employed by the HGM method (Smith 

 et al. 1995), and is illustrated by the following table, which assumes a two-acre impact to a 10-acre AA 

 for a hypothetical project. 



There are several possible ways to determine mitigation needs using this approach, including: 



o designing mitigation for individual functions or cumulatively for all functions using the 



greatest predicted loss in functional units as the replacement target (in this case, 

 designing mitigation such that each function provides a minimum 5.2 functional units or, 

 designing the mitigation such that, cumulatively, 5.2 + 5.2 = 10.4 functional units are 

 replaced); or 



o designing mitigation for individual functions or cumulatively for all functions using the 



average predicted loss in functional units as the replacement target {in this case, 

 designing mitigation such that each function provides a minimum 5 functional units [(4.8 

 + 5.2) ^ 2 = 5J or designing the mitigation such that, cumulatively, 5 + 5 = ]0 

 functional imits are replaced); or 



O designing mitigation for individual fiinctions or cumulatively for all functions using 



individual predicted changes in functional units as the target {in this case, 4.8 for 

 function A and 5.2 for function B, or cumulatively using 4.8 + 5.2 = 10 functional units). 



There may be circumstances that simply preclude the replacement of a given function/value parameter at 

 the same level at which it is rated for an affected wetland. For example, if a project impacts a wetland 

 rated "high" for uniqueness due to the presence of a bog, it is very unlikely that the uniqueness parameter 

 could be mitigated at the same level at a replacement wetland because there is no known method for bog 

 replacement. In virtually all cases, appropriate mitigation of lost wetland functions and values will be 

 subject to coordination/negotiation with the regulatory agencies involved in the project. 



It is not the purpose of this evaluation form to dictate wetland mitigation policy. What is and is not 

 considered appropriate mitigation will ultimately be determined by the regulatory agencies; primarily the 

 COE and EPA. While this evaluation method does provide a means for quantifying predicted impacts to 

 wetland functions and values, it is important to stress that coordination with the regulatory agencies as to 

 the application of this evaluation method and discussed mitigation determination strategies to a given 

 project is crucial and needs to be carried out on a project by project basis. 



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