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Table 1.2 <br />8 <br />Susceptibility of Wetlands to Degradation by Stormwater Impacts <br />Minnesota Routine Assessment Method for Evaluating Wetland Functions, Version 3.0 <br />Exceptionally Highly Susceptible Moderately Least Susceptible <br />24 <br />Susceptible Wetland Wetland Types:Susceptible Wetland Wetland Types: <br />13 <br />Types:Types: <br />aa <br />Sedge Meadows Shrub-carrsFloodplain ForestsGravel Pits <br />bb <br />Open Bogs Alder ThicketsFresh (Wet) MeadowsCultivated Hydric Soils <br />c, ec <br />Coniferous Bogs Fresh (Wet) MeadowsShallow MarshesDredged Material/Fill <br />Material Disposal Sites <br />d, cc <br />Calcareous Fens Shallow MarshesDeep Marshes <br />d, c <br />Low Prairies Deep Marshes <br />Lowland Hardwood <br />Swamps <br />Seasonally Flooded <br />Wetlands <br />1 <br /> Special consideration must be given to avoid altering these wetland types. Inundation must <br />be avoided. Water chemistry changes due to alteration by stormwater impacts can also <br />cause adverse impacts. Note: All scientific and natural areas and pristine wetland should be <br />considered in this category regardless of wetland type. <br />2 <br /> a., b., c. Can tolerate inundation from 6 inches to 12 inches for short periods of time. May be <br />completely dry in drought or late summer conditions. d. Can tolerate +12 inches inundation, <br />but adversely impacted by sediment and/or nutrient loading and prolonged high water levels. <br />e. Some exceptions. <br />3 <br /> a. Can tolerate annual inundation of 1 to 6 feet or more, possibly more than once/year. b. <br />Fresh meadows that are dominated by reed canary grass. c. Shallow marshes dominated by <br />reed canary grass, cattail, giant reed, or purple loosestrife. <br />4 <br /> These wetlands are usually so degraded that input of urban storm water may not have <br />adverse impacts. <br />Notes: There will always be exceptions to the general categories listed above. Use best <br />professional judgment. A more complete description of wetland characteristics under <br />each category is contained in Appendix A of the source (see footnote). Pristine <br />wetlands are those that show little disturbance from human activity. <br /> <br />8 <br />Adapted from: <br />Storm-Water and Wetlands: Planning and Evaluation Guidelines for Addressing Potential <br />Impacts of Urban Storm-Water and Snow-Melt Runoff on Wetlands, State of Minnesota Storm-Water Advisory <br />Group, June 1997. <br />Management Classification 8 <br /> <br />