Primary purpose
To evaluate wetland functions and values when addressing highway and other linear projects (e.g., pipelines and transmission lines). May also be used for other applications (e.g., mitigation projects) at the discretion of the user.
Expertise needed
Professional(s) who have training and experience in wetland science.
Applicable habitat types
Wetlands in Montana.
Categories assessed
Twelve functions and values: habitat for federally listed, proposed, or candidate threatened or endangered plants or animals; habitat for plants or animals rated S1, S2, or S3 by the Montana Natural Heritage Program; general wildlife habitat; general fish habitat; flood attenuation and storage; dynamic surface water storage; sediment/nutrient/toxicant retention and removal; sediment/shoreline stabilization; production export/food chain support; groundwater discharge/recharge; uniqueness; and recreation/education potential.
Procedure
The user(s) assembles available information (e.g., topo maps), visits the assessment area (AA), and completes the field evaluation form that (a) identifies the individual fields, (b) lists conditions for each field, (c) assigns a point (scale 1-7) for conditions used in assessing function/value, (d) includes an equation for calculating a score for most functions/values, and (e) includes tables for determining a rating (Low, Moderate, High) and functional points (scale 0 -1.0) for each function/value. Functional units are also calculated for each function/value and totalled. An overall analysis area rating (Category I, II, III, or IV) is assigned to the AA based upon the individual scores, functional points, and percentage of the possible functional points.
Key Terminology
Functions: self-sustaining properties of a wetland ecosystem that exist in the absence of society, and relate to ecological significance without regard to subjective human values.
Functional point: a numerical rating, ranging from 0 to 1, assigned to a particular function/value based on given criteria (Total functional points = sum of the individual functional points for an assessment area).
Functional unit: a figure derived by multiplying functional points for a given assessment area (AA) by its estimated acreage (Total functional units = sum of the individual functional units for an assessment area).
Overall analysis area rating: a rating (Category I, II, III, or IV) indicating the relative quality of the assessment area. For example, Category I wetlands are of exceptionally high quality and are generally rare to uncommon in the state. In contrast, Category IV wetlands are generally small, isolated, and lack vegetative diversity.
Percentage of the possible functional points: a combined measure of function/value for the assessment area used to provide an overall wetland ranking (% of possible = [% the total actual functional points ÷ the total possible functional points] X 100).
Rating: a rating (low, moderate, high) indicating the relative capacity of a wetland to perform individual functions/values.
Values: benefits that derive from either one or more functions and the physical characteristics associated with a wetland.
Contact persons
Lawrence Urban, Montana Department of Transportation, Resources & Permitting Bureau, 2701 Prospect Ave., P.O. Box 201001, Helena, MT 59620-1001 phone: (406) 444-6224; fax: (406) 444-7245; e-mail: u4004@long.mdt.mt.gov
Jeff Berglund, Morrison-Maierle Environmental Corporation, 910 Helena Avenue, P.O. Box 6147, Helena, MT 59604-6147 phone: (406) 442-3050; fax: (406) 442-7862; e-mail: jberglund@m-m.net
Output
Measure of individual function and value; and an overall rating of a site relative to wetlands in Montana.
Estimated time to assess 1 acre site
Total 1 hour per assessment area.
Total less than 1 hour: Complete evaluation form (step 1).
Comparison of habitat types
Can directly compare wetlands (from the same or different wetland class) within Montana.
Use as guide to design
The MT Form should not be used as a guide to design; however, individual variables (fields) may provide useful information. To attain a high score for general fish habitat, the wetland should be designed so that it is verified or suspected to support native fish. While fish may be relatively easy to control, some variables cannot be controlled by design (e.g., presence of amphibians, invertebrates, mammals). Also, the MT Form uses opportunity variables, but does not set upper limits on those opportunities that could potentially reduce functional capacity (e.g., direct discharge of industrial/municipal wastewater or evidence of accumulated sediment/excess nutrients is considered a preferred condition for the sediment/nutrient/toxicant retention and removal function). In some circumstances, a wetland may not have the capacity to remove all nutrient input. An upper limit on the opportunity must be defined to insure that the existing or planned wetland can predictably have the capacity to provide a function. Some variables may provide useful information. Users can refer to the variables to determine which conditions increase or decrease function. This can be translated into design criteria with explicit requirements (e.g., design so that wetland is connected to permanent stream).
Related procedures
None known.
Extent of use/field testing
The MT Form has been utilized on a consistent basis during the last two years by the Montana Department of Transportation (MDT) and consultants on all MDT projects and mitigation sites . The local US Army Corps of Engineers District has also designated that the MT Form be used by consultants and developers preparing permit applications on non-transportation projects (Pers. comm.: Larry Urban, MDT, Sept. 22, 1998).
Proposed future revisions
MDT plans to revise sections of and computerize the MT Form during fall/winter 1998-1999 with assistance from consultants, regulatory agencies, and MT Natural Heritage Program.
Key Reference
Berglund, J. 1996. MDT Montana Wetland Field Evaluation form and Instructions (July 1, 1996; Appendix A revised 9/23/1997). Prepared for the Montana Department of Transportation, Helena, MT. 19 pp. ppen.