Bioengineering your shoreline can save money, improve water quality
Save money, look beautiful and improve water quality by using native plants and biodegradable materials as lakescaping for your shoreline.
Bioengineering is defined by the Michigan Department of Environmental Quality (DEQ) as “using a combination of native planting and natural, or biodegradable materials to provide shoreline protection.” It also is often referred to as softshore engineering or lakescaping. This method is designed to provide a stable shoreline by protecting the shoreline from waves and erosion while at the same time improving ecological features and the integrity of the shoreline.
Many shorelines in Michigan use seawalls. These are a hard surface, such as wood, metal or concrete, that are installed to act as a buffer by blocking waves to keep them from reaching the adjacent land. Their primary purpose is to prevent erosion of the land. Continual erosion can result in the loss of land and increase sediment into the water which results in poor water quality.
Seawalls, while used frequently, can cause the shoreline to be less stable because they do not allow for any absorption of the wave energy coming into it. The waves hit the seawall and the energy gets bounced back out into the water. As it bounces back off the seawall, the wave energy picks up soil and sand causing erosion at the base of the wall called “scour.” This “scouring” reduces the stability of the seawall, decreases water clarity and has a negative impact on aquatic plants and animals.
A bioengineered or softshore engineered shoreline absorbs most, if not all, of the wave energy as it comes onto the shore. This reduces both erosion and scour providing more stability to the shoreline.
The use of native plants in an engineered shoreline also has other positive benefits for the lake, river and shoreline. Native shoreline plants absorb nutrients and other pollutants in surface runoff keeping them out of the water. Most native plants have extensive root systems compared to other plants such as turf grass. These roots help to anchor the soil in place and stabilize the shoreline. Native plants also limit erosion of the shoreline from wave action as mentioned earlier. Shoreline plants that hang out over the water increase shade for waterfowl and other aquatic animals and provide food close to the water’s edge. Finally, maintaining native vegetation will help to sustain the natural biodiversity and reduce nuisance species, such as phragmites or purple loosestrife, from infiltrating the area.
Using softshore materials, including native plants, rather than the typical hardscape seawalls can be cost effective as well as more attractive and stable. The comparative cost of a linear foot of softshore using all bioengineered materials and plants averages $10 to $20* for vegetative shoreline and $35 to $75* for riprap (rocks). The cost for a hard seawall can range from $45 to $200* per linear foot. Most of the difference in cost is due to labor. In many cases, the homeowner can install the softscaping themselves while a hard cement, wood or metal seawall must be installed by a professional contractor after obtaining all necessary permits.
In addition, MDEQ has created a project category that allows for an expedited permit application process for specific bioengineering practices to stabilize shorelines on inland lakes. The application process reduces both the cost and inconvenience of the permit process for small activities. The permit application can be found at www.mi.gov/jointpermit
More information is available from the MDEQ booklet Natural Shorelines for Inland Lakes
*MDEQ information based on calculations from Reston Associates; Coastal Systems International and U.S. Army Corps of Engineers.