MDT Montana Wetland Assessment Method May 25. 1 999 



Development (MDEQ 1999) with listed "probable causes" related to sediment, nutrients, or toxicants (e.g. not based exclusiveh' on 

 flow alteration, other habitat alterations, etc.), then the second column of the matrix should be used. Such related probable causes 

 include '"metals", "nutrients", "organic enrichment/DO", "'suspended solids", "unionized ammonia". "priorit]t' orgamcs", '"sUtation", 

 "other inorganics", "salinitv'/TDS/chlorides". etc. The impaired waterbody list is lengthy and dynamic and is not included as an 

 appendLX to this document; however, the list is available on the internet at hrtp://water.montana.edu/docs/tmdl/303d/303dContents htm 

 If the AA is not included on the MDEQ TMDL hst but high levels of these inputs are observed or e\-pected and are impairing other 

 functions at the AA. as evidenced bv observations of major sedimentation, major contaminant sources, major eutrophication. etc.. then 

 the second column of the matrix should be used. 



The nex! two variables address the percent of wetland vegetated cover and whether or not evidence of ponding or flooding occurs in 

 the AA (see indicators under 14E). respecti\eh-. The final variable determines the appropriate functional points and rating and pertains 

 to whether or not the AA contains a restricted (or no) outlet or an unrestricted outlet. 



14H. Sediment/Shoreline Stabilization: This field assesses the ability of the AA to dissipate flow or wave energv, reducing erosion. 

 Complete this field only if the jurisdictional wetland within the AA occurs on the banks of a river, stream, or other natural or manmade 

 channel, or occurs on the shoreline of a standing water body that is subject to wave action. Variables to consider when detennimng if a 

 waterbody is subject to wave action include estimated wind velocity, water depth, and fetch (distance across the water). Although not 

 required for application of this assessment method, Lrnsley and Franzini (1979) cite the following equation for determining wave 

 height: rise of wave (ft) = [(wind velocity [mph])' x fetch (miles)] ^ (1,400 x water depth [ft]). If this field does not apph'. circle NA 

 where indicated on the data form and proceed to the next fimction. 



Variables used to assess this fiinction are: percent cover of the wetland streambank or shorehne by si)ecies with deep, binding 

 rootmasses; and duration of surface water adjacent to rooted vegetation. GeneraU}', vegetation species with deep, binding rootmasses 

 are more efficient at stabilizing streambanks and shorelines than are species with minor root systems. Wetlands adjacent to surface 

 waters of longer duration generally provide this function more fi^equently than wetlands adjacent to surface waters of less duration. 



i. Rating. Working from top to bottom, use the matrix on the data form to arrive at [circle] the functional points and rating [H = higk 

 M = moderate, or L = low] for this fiinction. First, estimate the total percent cover of wetland streambank or shoreline by species with 

 deep, binding rootmasses. AH trees and shrubs are considered to have deep, binding rootmasses. With respect to herbaceous species, 

 annual plants are considered to lack such rootmasses. Pereimial herbaceous species van with respect to their root masses and should 

 be considered individually. Sedges and rushes, for example, are considered to provide deep, binding rootmasses, while Kentucky 

 bluegrass is not. 



Next, determine the longest duration of surface water adjacent to rooted vegetation in the AA using the definitions provided above 

 under #14C and circle the appropriate functional points and rating. 



141. Production Export/Food Chain Support: This field assesses the potential of the AA to produce and export food/nutrients for 

 living organisms. For purposes of this assessment "food/nutrients" include particulate and dissolved organic matter, plant forage 

 species, invertebrates, wildlife prey species, etc. 



Variables used to assess this function are: vegetated area in the AA; structural diversity; outlet (surface or subsurface) presence or 

 absence; and duration of stirface water. GeneralI^•, wetlands with greater areas of vegetation have potential for more forage plant 

 production and particulate and dissoKed organic material production than do wetlands containing smaller areas of vegetation. Plant 

 layers increase with structural diversitv. which tends to increase food chain support by providing forage species and cover for a greater 

 variety of wildlife and insect life. Wetlands with surface or subsurface outlets can more readih export organic material to downstream 

 habitats than can wetlands without outlets. AvaUabiUty of surface waters for use by fish, aquatic invertebrates, and aquatic wildlife, all 

 potential food chain constituents, generalN- increases with the duration of these waters. Also, opportunities for breakdown and export 

 of organic materials to downstream aquatic habitats via surface water are generally greater at wetlands containing such waters for 

 longer, rather than shorter durations. 



i. Rating. Working from top to bottom, use the matrix on the data form to arrive at [circle] the functional points and ratmg [H = high. 

 M = moderate, or L = low] for this function. For Factor A in the matrix, estimate the acreage of the vegetated component (all 

 vegetation including persistent non-persistent rooted, and floating) within the AA. Factor B pertains to the structural diversity ratmg 

 determined under #13. For Factor C. indicate (yes or no) whether the A.'\ contains a surface or likely subsurface outlet (see indicators 

 of recharge under 14J below). Finally, circle the appropriate functional points and rating based on the longest duration of surface water 

 in the AA using the definitions provided above under #14C. 



10 



