Lake Management Techniques: Erosion Control
By Gerald Dixon – Lake Management Committee
The brown color of our lake is the result of suspended bits of rock and soil in the water. This suspended material is called sediment. Sediment is generated by erosion, which is a geological process in which earthen materials are worn away and transported by natural terrestrial and aquatic forces, as well as human and animal influences. Lake sediment causes un-navigable waters, unwanted green algae blooms, and weeds among other unseen detriments to a healthy lake. Shoreline erosion contributes significantly to our lake’s sediment and water quality issues. Most homeowners will not dispute the fact that Rock Creek’s watershed is a carrier of sediment. But another major contributor is our thirty miles of shoreline. Here are some of the aquatic forces that lead to our shoreline erosion:
Waves: Wave action can displace loose soil when the soil composition isn’t right for the area and natural vegetation has been removed.
Ice: When lakes freeze and then melt, sheets of ice are pushed up onto the shore. This is occurring more and more frequently as water levels rise and fall.
Storm Water: As storm water moves over loose soil, layers of the soil are removed in “sheets” leading to something called “Sheet Erosion.”
Flowing water: Run off from the lake’s watershed and flow of material contribute to the overall deposits.
Splash or heavy rains: Precipitation and storm water hitting loose soil cause heavy displacement depending on the slope of the property.
Human influences also cause shoreline erosion to happen. This is often referred to as “accelerated erosion” which happens much faster than natural erosion and is much more challenging to reverse. Sometimes, people who are trying to help control shoreline erosion are actually causing much more damage in the process. Removing vegetation in order to create more visibility and access to the water not only destroys many natural habitats, but gets rid of the natural erosion control that plants and tree roots offer.
Aquatic plant removal can have a similar effect. Shallow lakes, such as ours, tend to have more aquatic plants near the shore. These plants help protect the shoreline from erosion by reducing a wave’s energy before it comes in contact with the shore. When too many aquatic plants are removed, the ecosystem in the lake is not only damaged, but the full erosive force of waves is able to hit the shoreline and cause damage there too.
When home owners install impervious surfaces such as driveways or permanent structures, that surface area is now unable to absorb water from precipitation. This precipitation will therefore cause erosion instead of absorbing into the soil naturally. Paved sitting or observation areas beside the lake and long docks have a dramatic effect on the shoreline.
But the most severe erosion from human influence is created by watercraft. When boats are design to create waves, such as those we wish to board behind without a line, the damage to shoreline is the greatest; fortunately, deep water waves are not as damaging as shallow water waves. This is the principal reason our “No Wake Zones” were created. Unfortunately, the majority of boat operators do not slow to minimum steerage speed as required by the regulation.
Again, what we do on our properties can affect the lake, so always consider it when you make changes, especially along the shoreline. We should all do our part to “Save our Lake” and as always…
Be Lake Responsible