A functional, eco-friendly shoreline for the future
A functional, eco-friendly shoreline for the future “Don’t get too close, the bank is crumbling and you’re going to fall in!” I can be heard telling my young nephews as they relentlessly pursue small fish, insects, and various amphibians with their dip nets at the lake’s edge. The lake banks seem to be getting worse in certain areas with every heavy rainstorm. Large chucks of the bank sheer off like icebergs calving from a glacier, leaving the edges steep and devoid of vegetation. And the topsoil needed for plants to reestablish has been added to the lake’s bottom sediment.
The look of a well-manicured lawn going all the way down to the water’s edge has been the typical condition that most lake and pond owners want. Keeping the banks mowed all the way to the water’s edge may look nice and neat, but it can leave the shoreline weak and unstable. If the only vegetation holding the banks together are turf grasses and shallow-rooted weeds, the banks are far more likely to develop erosion issues from wave action and gravity. There are several ways to mitigate shoreline erosion including regrading the banks, building retaining or seawalls, adding large stones (riprap) or gabions; but my favorite means of repairing and reducing shoreline erosion involves imitating nature. When left undisturbed, the water/land interface is typically high in plant and animal diversity. The high diversity of plant life means that there are shallow, medium, and deeply rooted plants whose roots form a matrix, helping to hold soil in place. Not only will the plants help stabilize the bank, but they can help improve water quality as they are the first line of defense against incoming sediment, excess nutrients, and pollutants from surface runoff.
Recently Aquascape Environmental was contacted by a residential community, Sky Lake in Helen, Georgia, to develop a plan to address their shoreline erosion issues around their signature lake within their community. Based on the site conditions and feedback from the community, Aquascape Environmental recommended a “low impact” method of utilizing native aquatic plant materials in conjunction with natural biodegradable materials. To “test” the applicability of this process to halt erosion, it was decided that the first phase of the project would be a demonstration that would include fifty feet of shoreline.
Two of the critical elements of establishing aquatic plants in a lake or pond are having the correct water depth and having an adequate soil media structure for the plants to survive and prosper. The normal installation procedure to establish the parameters for this type of project dictates that the water elevation of the lake be temporarily lowered to facilitate the placement of soil needed for the project. The process can be cumbersome and can also require additional regulatory permitting for the project, which adds to the timing and cost.
After reviewing the issues involved, Aquascape Environmental decided to utilize a “low impact” method of establishing the correct water depth and soil media that was needed. This process was completed by pre-filling burlap bags with a soil compost mix and placing the soil bags directly along the edge of the lake. The native plants were installed directly into the burlap bags that will biodegrade within two-to-three months, which will be enough time for the plants to become established. Another element of the construction was the placement of a coir log along the edge of the bags on the lakeside. Coir is made from the husks of coconuts and is a natural product that will biodegrade in time—although it is very durable and has a life span of two-to-three years in wet conditions. The coir log serves to protect the new plantings during the establishment period and greatly increases the success of the project.
Based on the success of this demonstration project, Sky Lake has already decided to move forward with addressing additional bank areas of the lake that are affected by erosion. Aaron Cosson, the general manager of Sky Lake commented, “The first phase of our shoreline restoration project has been a huge success! Everyone who has had a part in this project has been beyond pleased, and we are looking forward to the next phases. The staff at Aquascape Environmental are extremely knowledgeable and make projects such as this go as smoothly as possible. It is always a pleasure doing business with them”.
The success of the project has been able to halt the progression of erosion of the lake banks as well as increase the biodiversity of the area. By creating a favorable habitat, other beneficial species of plants began to take root all on their own. The increase in vegetation also creates new habitats for small animals. Small fishes, amphibians, and reptiles can take refuge around the emergent plants. Birds are drawn to some of the plants as a food source, for nesting material, or even as nesting sites. This shoreline restoration project included a variety of native species that bloom at various times of the year which benefits pollinators and is aesthetically appealing to the public all season long—this is a big win for the community and the environment.
Article by James Stone – Lake Operations Environmental Specialist
