Development and vegetation removal on or near bluffs and steep slopes often results in erosion, slope failure, landslides, and visual impacts to these sensitive natural features. The interaction of geologic and hydrologic factors affect bluff and slope stability. Geological factors include bedrock type and location, soil type, slope angle. Hydrological factors include the quality of vegetation cover, intensity and duration of precipitation, and the presence of springs. Land development and land alteration change the way water moves across and through the land and along with increased frequency and intensity of rainfall can increase risks.
Professional inventories and studies can help communities better assess failure risk, so they can put appropriate measures in place to ensure future development is safe and does not increase risk. To learn what other communities are doing and available resources, see:
Strategies for Reducing Risk of Slope Failure
Strategies for reducing the risk of slope failure vary depending on local risk factors. General approaches include:
- Avoid land disturbances on or near slopes to minimize slope erosion
- Establish and maintain vegetation that helps stabilize slopes
- Avoid the placement of stormwater treatment facilities or septic drainfields on slopes or near the top of slopes
- Regulate the placement of structures and land alterations in bluff and steep slope areas
- Using erosion-control and stormwater management measures to reduce erosion and overland flow
- Public education and outreach
Methods for Identifying and Evaluating Slopes
These resources are helpful for identifying slopes and evaluating their extent for preliminary site evaluations and land use planning purposes. An on-site survey is recommended for determining zoning compliance including structure placement.
- MNTOPO - an easy-to-use web application for viewing, printing and downloading lidar-derived elevation data. Please see the tutorial Identifying Bluffs and Steep Slopes with MnTOPO.
- Identifying Bluffs in Shoreland - To identify bluffs in shoreland districts, this technical guidance document provides a step-by-step approach for identifying bluffs in the shoreland district along with two examples.
- DNR Bluff Mapping Tool an ArcMap add-on for evaluating larger geographic areas, available on the Minnesota Geospatial Commons.