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A.) Runoff must not be discharged directly into wetlands without appropriate quality and <br />quantity runoff control, depending on the individual wetland's vegetation. See the current <br />version of the Minnesota Pollution Control Agency's publication, "Storm-Water and <br />Wetlands: Planning and Evaluation Guidelines for Addressing Potential Impacts of Urban <br />Storm-Water and Snow-Melt Runoff on Wetlands" for guidance. (Commentary: The <br />sensitivity of a wetland to degradation varies with vegetation type. Sedge meadows, open <br />bogs and swamps, coniferous bogs, calcareous fens, low prairies, lowland hardwood <br />swamps, and seasonally flooded basins are highly sensitive to degradation, while flood <br />plain forests, reed canary grass meadows, shallow (reed canary grass, cattail, giant reed or <br />purple loosestrife) marshes are only slightly sensitive to degradation.) <br />B.) At the minimum a one hundred (100) foot wide protective buffer strip of native <br />vegetation must surround all wetlands. The width of this buffer strip muse be <br />increased at <br />least two (2) feet per one (1) percent of slope of the surrounding land. (Commentary: <br />"Native"vegetation is preferred, since some non-native plant species can out compete <br />native species and create amono-culture of decreased environmental value. Useful <br />references are the Minnesota Pollution Control Agency's publications "Buffer Zones" <br />and "Soil Bioengineering. " <br />Detailed buffer design is usually site specific. Site specific design criteria should <br />follow <br />common principles and the example of nearby natural areas. The site should be <br />examined for existing buffer zones and mimic the slope structure and vegetation as <br />much <br />as possible. The function of the buffer is a better indicator than the width. Buffer <br />design <br />and protection during construction should do any or all of the following: slow water <br />runoff, trap sediment, enhance water infiltration, trap fertilizers, pesticides, pathogens, <br />heavy metals, trap blowing snow and soil, and act as corridors for wildlife. How much <br />stress is put on these functions will determine the buffer zone's final configuration. <br />Native plant species have root systems and growth characteristics that are well suited <br />to buffer functions. Useful guides for starting the plant selection include Minnesota <br />Department of Transportation's seeding manual, and their "Plant Selection Matrix" <br />CDItOM. Good plant species design stresses diversity and allows plant succession and <br />zoning of the species from wet soil preference to drier upland species.) <br />C.) Wetlands must not be drained or filled, wholly or partially, unless replaced by either <br />restoring or creating wetland areas of at least equal public value. (Commentary: For <br />example, a groundwater fed Type 4 wetland should be replaced with another groundwater <br />fed Type 4 wetland..) Replacement must be guided by the following principles in <br />descending order of priority.) <br />1.) Avoid the direct or indirect impact of the activity that may destroy or diminish the <br />wetland. <br />14 <br />