A Certified Natural Shoreline Professional can help you understand a shoreline’s erosion potential

Bindu Bhakta<bhaktabi@msu.edu>, Michigan State University Extension - July 30, 2014

The Michigan Natural Shoreline Partnership offers highly trained marine and landscape professionals available to assess the causes of shoreline erosion and develop a customized solution particularly designed for your shoreline.

A Certified Natural Shoreline Professional can help you understand a shoreline’s erosion potential. Photo: Melanie Foose l MSU Extension

In July 2014, the North American Lake Management Society (NALMS) and numerous others who enjoy inland lakes across the country celebrated Lakes Appreciation Month. Although the designated month is over, the celebration does not have to end. In Michigan, where there are more than 11,000 inland lakes, there is much to know about our water resources.

You may want to take a few minutes to locate resource professionals who can help you and your neighbors better understand the many aspects of your lakeshore, including helping you assess any erosion along your shoreline. Erosion, the wearing down and washing away of soil and rocks, comes in many forms and various levels of severity at the shoreline.

There are several causes for shoreline erosion. Keep in mind that erosion can occur naturally or be human-induced.

Overland flow/stormwater runoff- Much of the precipitation (rain and snow) that hits the ground’s surface will filter downward through the layers of soil and rock and recharge the groundwater supply below. In contrast, water, from precipitation, can flow directly across the surface of the ground rather than soaking into it. The latter is referred to as overland flow or stormwater runoff. Natural features such as slope, soil type and drainage pattern, combined with human activities (for example, the replacement of soil with concrete and other impervious surfaces that prevent the downward movement of water), help determine the volume and velocity of overland runoff. As it moves across the land, it can pick up soil particles and other pollutants, carrying them directly into a lake or stream. Overland runoff may form gullies and result in bank failure.
Groundwater seepage or springs- This type of drainage typically occurs when water table meets the land surface. This may present itself as either a wet area or a visible flow of water. In either case, the seepage can result in soil loosening that can then transported into a lake.
Removal of shoreline vegetation- One important thing plant roots do is to hold soil in place. When plant root systems are removed from the shoreline on land, the bank becomes vulnerable to waves and wind, and can begin to fail over time. Since soil particles tightly bind nutrients to their surfaces, keeping them out of lakes also reduces a source of excess nutrients into the water and thereby protects lake water quality. Soil compaction and bank trampling caused by excessive foot traffic can also cause plants to die and shorelines to erode. In the water, plants as well as coarse woody debris such as tree trunks and large tree limbs can help protect the shore from wave and winter ice and act to keep sediments from stirring up from the bottom of the lake.
Waves- The most common cause of shoreline erosion is wave action. Naturally, lake size, shape, bottom contours and direction of prevailing winds are all factors which influence the natural impact of waves. Humans magnify the effect of waves through recreational activity on lakes.
Ice action- During winter, as ice warms and expands due to rising temperatures, ice can push up onto the shoreline and form ice ridges, which can cause the bank to move. The removal of ice ridges, however, is not recommended because they can protect the bank from further erosion.

Erosion can take place at a gradual almost unnoticeable rate, at a fast rate, or somewhere in between. Determining if your shoreline is affected by a fast or slow rate of erosion is a key factor in determining whether you need to consider an erosion control plan. Before you make this decision, it is necessary to understand what the potential wave energy and ice action are at your shoreline.

Wave energy can be categorized as low (low potential for erosion), moderate or high (great potential for erosion). To determine the wave energy at your site, a tool you can use is the Wisconsin online Erosion Calculator. You will want to calculate the wave energy at your site before you consider developing a shoreline erosion protection plan. To use this calculator, you will need a lake map which includes the contours of the bottom of the lake. The Michigan Department of Natural Resources has 2,700 maps on file that are available for download.

Help is available from the Michigan Natural Shoreline Partnership (MNSP), a diverse group of statewide partners including Michigan State University Extension. MNSP’s goals are to train contractors and landscape professionals who work at the water’s edge, educate lake residents about the importance of natural shorelines, provide demonstration shoreline landscapes that people can visit to see what can be done to combat issues encountered at the water’s edge, and encourage local and state policies that promote natural shoreline management.

If you need help with an erosion control project, consult with a Certified Natural Shoreline Professional (CNSP). If you are ready to take the next step in helping to protect your shoreline, also consider picking up an excellent resource on the topic of natural shorelines, the Natural Shoreline Landscapes on Michigan’s Inland Lakes: Guidebook for Property Owners which is available for purchase from the MSU Extension Bookstore.

The Tipp of the Mitt Watershed Council’s “Understanding, Living With, & Controlling Shoreline Erosion” is another great resource for more information on shoreline management. Also check out the resources available from the local Michigan Chapter of NALMS, also known as McNALMS.

Though Lakes Appreciation Month may have already come to an end this year, it is never too late to get to know your lakeshore better. Consider hiring a Certified Natural Shoreline Professional today!

Other articles in this series:

This article was published by Michigan State University Extension. For more information, visit https://extension.msu.edu. To have a digest of information delivered straight to your email inbox, visit https://extension.msu.edu/newsletters. To contact an expert in your area, visit https://extension.msu.edu/experts, or call 888-MSUE4MI (888-678-3464).