Publicly-owned land along Madison’s lakes and major rivers have different types of shorelines that the Engineering Division works to stabilize. Vertical, rapidly eroding slopes can drop soil into our lakes and waterways; this worsens water quality and can be detrimental to trees or hard structures.
Depending on the conditions of the shoreline, the following stabilization methods are implemented:
The majority of native plants have deep root structures that naturally stabilize the shoreline. The use of native vegetation:
- Is appropriate where there is no significant, long-term water level fluctuation
- Is appropriate on smaller rivers or lakes that typically don’t experience waves and ice shoves
- Is appropriate where plants can grow successfully
- Can be used in conjunction with Rock Riprap or other hard features; native vegetation placed above these features provides additional stabilization and protection during high water levels or large wave action
- Typically requires stabilized soil/coir log to provide a planting medium in inundated areas
A common hard-armor technique which consists of large rocks placed in the water and up along the shoreline, rock riprap:
- Is appropriate on larger lakes (Mendota and Monona) and channels with large fluctuating water levels (Yahara River, Starkweather Creek etc)
- Is lined with geotextile fabric (a densely woven material) to prevent slumping when wave action removes soil from behind the rocks
- Protects shoreline from ice shoves and wave action
- Frequently includes installation of native vegetation along the top bank of the riprap to assist with stabilization during flood events
- Typically is placed at the 100-year flood elevation plus the wave height to prevent scouring, erosion and sink holes developing behind the riprap. You can find lake level information for Madison lakes on Dane County's Lake Level webpage.
Limestone steps and other lake access features are also often located along shorelines to create equitable water access throughout the City.