MDT Montana Wetland Field Evaluation Form and Instructions July I, 1996 



Category /F wetlands are generally small, isolated, and lack vegetative diversity. These sites provide 

 little in the way of wildlife habitat, and are often disturbed or occur immediately adjacent to disturbance. 

 To be rated as a Category FV site, the AA must not qualify as a Category I, II, or III site and: 



o Achieve a "Low" rating for Uniqueness ; and 



Achieve a "Low" rating for Production Export'Food Chain Support (e.g., less than one acre in 



size and low to moderate habitat diversity); and 

 o Total actual functional points < 30% (round to nearest tenth) of total possible functional points 



The overall rating can be used to establish wetland avoidance/protection strategies at the project level. 

 For example, if wetland impacts are unavoidable for a given project, and alternatives are available such 

 that a choice can be made between affecting a Category I or a Category III site, the applicant and 

 reviewing agencies could direct impacts to the Category III site. Other applications of the overall rating 

 concept may include the eventual development of mitigation ratio policy (e.g., mitigate impacts to 

 Category I sites at a 2: 1 ratio. Category 11 sites at a 1 .5: 1 ratio. Category III sites at a 1 : 1 ratio, and 

 Category FV sites at a 0.5: 1 ratio). Compensatory wetland mitigation guidelines for Montana are being 

 developed by an interagency team as part of the local procedures that will provide guidance for the 

 establishment, use, and operation of mitigation banks in Montana (Hazelwood pers. comm.). 



Functional units are not used in determining the overall rating, but are provided for the evaluator's 

 consideration in assessing project impacts, mitigation needs, or in assessing mitigation plans or the 

 success of constructed projects. An example of how functional units could be used to develop mitigation 

 that would replace overall (cumulative) functions and values for a given project is presented below. 



The total actual functional points for a given 8-acre AA is 6.3. Total functional units for the AA would 

 be calculated by multiplying 6.3 points x 8 acres = 50.4 Junctional units. A proposed highway project 

 would impact 2 acres of the AA. Assuming a relatively uniform distribution of functional capacity across 

 the AA, the loss in functional units to the AA would be 2 acres x 6.3 points = 12.6 functional units. To 

 compensate for lost wetland functions and values, mitigation would need to be designed that would 

 replace the functional units. If the predicted total actual functional points for a mitigation project was 

 5. 1, and the goal were to replace 12. 6 functional units, the applicant would need at least 2. 5 acres of 

 mitigation to compensate for the loss (2.5 x 5.1 =12. 6). If limited to a two-acre mitigation site, the 

 applicant could design the mitigation project such that the predicted functional points met or exceeded 

 6.3, resulting in the replacement of at least 12.6 functional units (2 x 6.3 = 12.6), or could obtain an 

 additional site such that the sum of the functional imitsfor the two sites met the total 12.6 point 

 replacement requirement. 



If the 8-acre AA was classified as a Category II wetland, and mitigation policy dictated that Category II 

 functional units be replaced at a 1.5:1 ratio, then the functional units that would need to be replaced 

 would be 12.6 X 1.5 = 18. 9. This would require the applicant to increase the acreage of his/her 

 originally-proposed mitigation project to 3. 7 acres (18.9 ^ 5. 1) or to alter the design, if possible, such 

 that the predicted functional points for the site were increased to reach the 18.9 functional unit 

 requirement. 



Functional Units can also be examined on a function by function basis to compare existing pre-project 



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