MDT Montana Wetland Assessment Method May 25. 1999 



actual functional points ^ total possible functional points X 100 



Determine the appropriate overall rating (described below) based oq the criteria indicated on the form. 



Category I wetlands are of exceptionally' high quality and are generally rare to uncommon in the state or are important from a 

 regulatory standpomt. Category I wetlands can: pro\ide primaiy habitat (see definition) for federally listed or proposed threatened or 

 endangered species; represent a high qualit>' example of a rare wetland t},-pe; provide irreplaceable ecological functions (e.g., are not 

 replaceable within a human lifetime, if at aU); exhibit exceptionalh high flood attenuation capability; or are assigned high ratings for 

 most of the assessed fiinctions and values. To be rated as a Category I site, the AA must: 



• Score 1 functional point for Threatened or Endangered Species (e.g., is documented primary habitat); or 



• Score 1 functional pomt for Umqueness (e.g., be rare in the USGS Unit and a bog, fen, warm springs or mature forested wetland 

 or "SI" plant association in an undisturbed condition); or 



• Score 1 functional point for Flood Attenuation and answer to C^iestion 14E.ii is '^es" (e.g., contains flooded wetlands in excess of 

 10 acres that are comprised of more than 75% woody vegetation, has a restricted outlet, and there is p)otential for flood damage 

 downstream); or 



• Total actual fiinctional points > 80% (round to nearest tenth) of total possible fiinctional points. 



Category II wetlands are more common than Category I wetlands, and are those that provide habitat for sensitive plants or animals, 

 fiinction at very high levels for wildlife/fish habitat, are unique in a given region, or are assigned high ratings for many of the assessed 

 fiinctions and values. To be rated as a Category II site, the AA must not qualify as a Category I site and: 



Score 1 functional point for Species Rated SI, S2, or S3 by the Montana Natural Heritage Program (e.g., is documented 



primary habitat); or 



Score .9 or 1 functional point for General Wildlife Habitat (e.g.. e\'idence of wildlife use is substantial and habitat quality is 



high to exceptional or evidence of wildlife use is moderate and habitat quality is exceptional); or 



Score .9 or 1 functional pomt for General Fish/Aquatic Habitat (e.g.. contains native game fish and habitat quality is high to 



exceptional or contains introduced game fish and habitat quality is exceptional); or 



Achieve "High" or "Exceptional" ratmgs for both General Wildlife Habitat and General Fish/Aquatic Habitat; or 



Score .9 fiinctional point for Uniqueness (e.g., bog, fen, warm springs, mature forested, or "S2" wetland community common 



in the watershed but with low disturbance or bog, fen, warm spnngs, mature forested, or "S2" wetland co mmuni ty rare in the 



watershed but with moderate disturbance); or 



• Total actual fiinctional points > 65% (round to nearest tenth) of total possible functional points. 



Category III wetlands are more common, generally less diverse, and often smaller and more isolated than are Category I and 11 

 wetlands. They can provide many fimctions and values, although they may not be assigned high ratings for as many parameters as are 

 Category I and U wetlands. To be rated as a Category in site, the AA must not qualLf\' as a Category I. II. or IV site. 



Category II ' wetlands are generally small, isolated, and lack vegetative diversity. These sites provide little in the way of wildUfe 

 habitat, and are often directly or indirectly disturbed. To be rated as a Category' FV site, the AA must not quaUfS' as a Category I. II. or 

 ni site and: 



• 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 

 structural diversity); and 



• 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 HI site, the applicant and revie'wing 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 II sites at a 1.5:1 ratio, Category EI sites at a 1:1 ratio, and Category IV sites at a 0.5: 1 ratio). 



Functional units are not used in determining the overall rating, but are pro'vided 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 fimctional units 

 could be used to develop mitigation that would replace overall (cumulative) fiinctions and values for a given project is presented 



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