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constructed without DNR approval or a work <br />in public waters permit as required by Minn. <br />Stat. § 103G.245, subd. 1 (2015). The work in <br />public waters permit is intended to ensure <br />that work or alterations to a public water <br />below the OHWL do not obstruct navigation <br />or water flow or negatively impact aquatic <br />and near shore habitat. There are many <br />instances where retaining walls and riprap <br />have been installed at a scale significantly <br />larger than that needed to correct erosion <br />problems. The overuse of these <br />mechanisms negatively impacts both <br />riparian vegetation and habitat. (See Figure <br />12.) <br />Figure 12. Example of riprap installation extent greater than needed to <br />control erosion, with significant impacts on riparian vegetation and <br />habitat. <br />Management of activities located further from the shoreline can also significantly reduce storm water <br />runoff. It is well documented that increases in impervious surfaces on the landscape affect both water <br />quantity and quality. Negative impacts to the water quality of a river or stream typically occur when the <br />impervious coverage of the watershed approaches 10 to 15%.18 Increased storm water runoff can affect <br />the stability of slopes and bluffs and give rise to significant safety concerns. <br />The improper placement of storm water facilities can also increase the risk of slope failure. When placed <br />on or near the tops of slopes, infiltration of storm water can saturate the soil around and below the <br />facility, which can increase slope instability. High intensity rainfall events may load slopes, filling soil <br />pores and reducing the capacity of soil to infiltrate water. Geologic factors are important factors in slope <br />stability but the presence of saturated soils that receive additional, intense precipitation increases the <br />risk of instability and failure.19 <br />Subpart 1. Purpose. This part establishes standards to protect sensitive resource areas from disturbance <br />and adopts a permitting process to regulate both land disturbance and storm water runoff in sensitive <br />bluff and shore areas to prevent the negative impacts associated with these types of disturbances, <br />including degradation of water quality and bluff instability. <br />Subpart2. Definitions. This part rule relies on the following terms: <br />• "Water quality impact zone" is used to identify areas at risk of erosion and of transmitting <br />sediment into a public water. It includes the shore impact zone. <br />• "Fully reconstructs" refers to the reconstruction of existing impervious surface. The definition is <br />consistent with the definition used by MPCA's Minimal Impact Development Standards (MIDS) <br />18 Schueler et al. 1994. <br />19 Jennings. 2015. <br />59 <br />