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^ 5.2 Impacts to WsTLAmDS <br />With the passage of wetland protection legislation, and construction of <br />ponds for runoff management, the rate of degradation from urban <br />development has been greatly slowed. However, with intensive land <br />development, agricultural production, and housekeeping practices in <br />developed areas, degradation of wetlands continues. The focus of <br />recent wetland legislation, policy, and practice has been to preserve the <br />functions, values, and overall quality of wetlands by minimizing poor <br />water quality and unmanaged quantities of mnoff associated with ogro- <br />urban Impacts. <br />5.2.1 Water Quality Impacts <br />Water quality plays a significant role in the overall quality of a wetland. <br />When the quality of incoming water dedines. the plant community may <br />degrade to fewer of species and retain only species tolerant of high <br />nutrient and sediment loads. A degraded plant community results o less <br />valuable ecosystem in terms of biodiversity, habitat, and aesthetics. <br />There are two primary factors that affect the quality of runoff entering a <br />wetland, and therefore to overall water quality within the wetland: <br />1. phosphorous, as the primary nutrient of concern <br />2. sedimentation, resulting from erosion of soil. <br />5.2.2 Water Quantity Impacts <br />Recent surface water management plans have protected wetlands from <br />nutrients but not from fluctuation of water elevation (bounce) or duration <br />of inundation. In fact, it was common to use wetlands to reduce floodirig <br />potential by sizing pipes to maximize bounce and duration. <br />The findings of the (State of Minnesota) Storm Water Advisory Group were <br />published in a document called Guidance For Evaluating Uhoan Storm <br />Water and Snowmelt Runoff Impacts To Wetlands (1994). The fincings <br />indicated that there is a broad range of tolerance to bounce and <br />duration among different wetland typjes. And to a lesser extent, the <br />range of tolerance con be attributed to the characteristics and quality of <br />a given wetland. <br />Some wetlands (e.g., bogs and fens) are sensitive to any disturbance and <br />will show signs of degradation with even low-level inputs of runoff. <br />Conversely, some wetlands (e.g., floodplain forests) are better adopted <br />to handle fluctuating water levels often associated with runoff. <br />OtyofOnno <br />Sijrtiee w»terMan»gwtmtPlan