Development,vegetation removal, and land disturbances on or near steep slopes commonly leads to slope erosion and failure. Vulnerability to these impacts varies based on geology, soil, hydrology, and slope angle, and hydrologic conditions. Property owners and communities should understand these risks to minimize impacts from existing and future development.
Strategies for Reducing Risk of Slope Failure
Strategies for reducing the risk of slope erosion and failure include:
- Avoid land disturbances and placing structures on or near steep slopes
- Establish and maintain vegetation to stabilize slopes
- Use erosion-control measures to minimize erosion during land disturbances
- Avoid placement of stormwater facilities, outfalls, or septic drainfields on slopes or near top of slopes –overland flow should be directed away from slopes when possible
Bluff Protection Standards in Minnesota
Local zoning controls apply many of these strategies by regulating development around lakes and rivers – consistent with state regulations. These standards are summarized on this page.
Evaluating Slopes for Local Zoning Administration
Following are planning and zoning resources to help administer bluff and slope protection standards. A site survey is recommended to determine the physical location of a bluff or steep slope and structure setbacks for permitting purposes.
- Quick Guide to Analyzing Slopes with MnTOPO – MnTOPO is an easy-to-use DNR web application for quickly analyzing slopes using LiDAR-derived contour lines. This tool can help determine whether a slope of interest is likely to meet the local zoning definition of a steep slope or bluff. GIS users can also download elevation shapefiles through MNTOPO as well.
- Identifying Bluffs in Shoreland - This technical guidance document explains how to understand and apply the shoreland bluff definition using a step-by-step approach and two examples.
- Shoreland Bluff Profile Tool – This Excel tool uses elevation data downloaded from a slope profile created in MnTOPO. This tool may be helpful to communicate with property owners where bluffs likely exist, including the locations of bluff impact zones and bluff setbacks for structure placement. This tool takes some time to learn how to use and is best used after the presence of a bluff is determined to likely exist using MnTOPO. The tool does not replace the function of a physical survey.
- Bluffs in Shoreland – This training explains why we have bluff regulations and what those regulations are. Training also works through sample elevation data to determine if a bluff exists using the bluff-related definitions.