The photo here shows a seawall on Glen Lake that has been replaced by a natural shoreline.
Do you know how many seawalls are on the Glen Lake shoreline? A seawall is defined as an engineered concrete, steel, or wood structure at the water’s edge that typically is designed to curb shoreline erosion where it is installed. Interestingly, the August 2017 shoreline survey on Glen Lake indicates there are currently 18 seawalls, each about 100 foot long representing approximately 1800 feet of shoreline. Some riparians use “rip rap” or stones to“harden”their shorelines as a preferred line of protection from erosion. The use of rip rapis not considered a seawall. Rip rap when used in conjunction with other erosion prevention measures such as core log installation and native plantings can actually absorb wave energy, prevent shoreline erosion and create wildlife habitat.
The entire shoreline of Glen Lake is approximately 17 miles long. Simple math tells us our shoreline is mostly seawall-free. It is widely accepted by watershed protectors that this current ratio is a good thing. Ideally, the entire shoreline of Glen Lake should be seawall-free. Seawalls on inland lakes like Glen Lake tend to be problematic for water quality due to the fact they removevitalwildlife habitat, do not absorb and filter nutrient runoff from landand deflectand even intensifywave energy onto nearby shorelines causing increased erosion and sedimentation of the water. Thereby invitingmore seawalls, which would create the “need” for more seawalls, and so the story goes. In fact the MDNR does not identify any Michigan inland lake environment as an appropriate or necessary application of Seawall type erosion prevention measures. A much better use of seawalls can be found on the Great Lakes wheresignificantly higherwave energyoccurs.
Installation of a seawall is expensive. However, there is a win-win option to install something far less expensive and much more lake-friendly. To learn more about removing a seawall or to consider other options for shoreline protection click on this link.
On October 17th, GLA Watershed Biologist Rob Karner, together with Dennis Wiand, Owner of Zero Gravity, LLC, presented a Leelanau Clean Water program to a group of over 30 key lake stewards from lakes around the region. Thanks to the Glen Lake Association’s willingness to be the first to use drone technology for conducting shoreline surveys, many other lakes have either followed the GLA’s lead, or are giving serious consideration to using drones as a water quality data gathering tool.
The key benefit of having a shoreline videotaped via drone is to establish a benchmark for the current condition of the water’s edge. Future drone surveys will be created and compared to the original survey thereby setting up the perfect comparison opportunity.
The kind of water quality data gathered is still evolving and future updates on the results of Glen Lake’s first survey, done in August of 2017, will come in subsequent communications. Examples of water quality data that are being quantified and placed on the map include: Green belts; drainage pipes; sea walls; rip rap; erosion; fish habitat; lake-water irrigation; road ends; inlets, and invasive plants.
While the use of the drone is proving to be a valuable, water quality-monitoring tool, GLA will continue to monitor the water chemistry using the hydrolab, collect and analyze plankton every month in the spring, summer and fall, and participate in the volunteer-based statewide water quality monitoring program.
Can you self-monitor your own shoreline?
One way you can monitor the water quality on your shoreline is to place two or three clean, volleyball-sized rocks at the water’s edge and wait to see if they become covered with green algae. If they are covered within a few weeks during the growing season with a healthy crop of algae, then you may have a nutrient loading problem that will need investigation.