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Existing development in portions of the LRRWMO limits the available physical space for capital <br />improvements to address local flooding issues. Appropriate rate and volume control applied throughout <br />the watershed are necessary to minimize future flooding issues. The LRRWMO's regulatory program <br />includes criteria intended to limit adverse impacts to floodplains and minimize flooding. The negative <br />impacts of flooding may be further minimized by thoughtful management of the floodplain achieved <br />through education and other activities. <br />Sediment is a major contributor to water pollution. Stormwater runoff from streets, parking lots, and other <br />impervious surfaces carries suspended sediment consisting of fine particles of soil, dust, and dirt. <br />Abundant amounts of suspended sediment are carried by stormwater runoff from actively eroding areas, <br />including unstable or degraded stream and lake shorelines. <br />Although erosion and sedimentation are natural processes, they are often accelerated by human activities, <br />including development and other land use changes. Loss of vegetation limits the ability of the landscape <br />to intercept rainfall and slow stormwater runoff, limiting the opportunity for runoff to infiltrate into the <br />soil. Land development may also result in the grading and filling of natural depressions that previously <br />provided temporary storage of rainfall and opportunities for infiltration and sediment removal. Increased <br />precipitation volumes and intensities can also result in increased stormwater runoff, further accelerating <br />upland erosion and contributed to higher flows in downstream resources, accelerating streambank <br />erosion. Erosion along the Rum River was specifically identified as an issue by the TAC and CAC during <br />Plan development, <br />Regardless of its source, sediment deposition decreases water depth, degrades water quality, smothers <br />fish and wildlife habitat, and degrades aesthetics. Sediment deposition can also wholly or partially block <br />culverts, manholes, storm sewers, etc., increasing flood risk. Sediment deposition in detention ponds and <br />wetlands also reduces the storage volume capacity, resulting in higher flood levels and/or reducing the <br />amount of water quality treatment provided. Erosion also results in channelization of stormwater flow, <br />increasing the rate of stormwater runoff and further accelerating erosion. As erosion and sedimentation <br />increase, the stormwater management systems (e.g., ponds, pipes) require more frequent maintenance, <br />repair, and/or modification to ensure they will function as designed. <br />The LRRWMO implements a permit program and associated performance standards to limit the <br />opportunity for excessive erosion and sedimentation. In addition, owners and operators of construction <br />sites disturbing 1 or more acres of land must obtain a National Pollutant Discharge Elimination System <br />(NPDES) Construction Stormwater Permit from the MPCA. A key permit requirement is the development <br />and implementation of a Stormwater Pollution Prevention Plan (SWPPP) with appropriate best <br />management practices (BMPs) that address erosion and sediment control. <br />Healthy wetland systems, shoreland areas, riparian areas, and natural spaces are critical components of <br />the hydrologic system and positively affect soil health, groundwater, surface water quality and quantity, <br />3-6 <br />