Work must be done to keep Asylum Lake alive.
Hydrologists from WMU and elsewhere report that the water quality of Asylum Lake and Little Asylum is poor. While researchers continue to monitor, test, and learn more about what we all might do improve its quality, much is already known.
The major pollutant in the lakes is phosphorus from fertilizer used on yards and gardens of area homes, apartment complexes, and businesses. Phosphorus enters the lakes via groundwater and storm sewer inflow. Studies show that most of it stays in the lakes’ sediment and surrounding groundwater.
Phosphorus causes increased growth of algae and other plants (biomass). These, in turn, remove oxygen and block sunlight from the water. Whether growing or decaying, algae and biomass remove oxygen from the water and make the water stagnant and unhealthy for fish and other aquatic life.
The best way to reduce phosphorus loads in the Preserve is to stop it at its source, i.e., get homeowners and business owners to reduce their use of fertilizers. Storm sewer drainage into the Preserve can also be adjusted so that phosphorus drains first into filtration and treatment systems or into soil where some of it will remain.
It’s harder to limit the salt that runs into the lakes from roads, sidewalks, and parking lots surrounding the Preserve. We can, of course, ask neighbors, business owners, and our municipalities to limit salt use in winter. Yet, we all know the perils of walking and driving on icy surfaces.
But salt never disappears from water, even as it moves through the soil. And the salt level in the Preserve’s lake water is rising.
One way that lakes stay healthy is through a twice-a-year natural cleansing and aerating process called inversion or “lake turnover.” In the fall, water on top of the lake cools and sinks, while the warmer bottom water rises. This process reverses in the spring. It’s nature’s way of supplying oxygen-rich water from the surface layer to the stagnant water at the bottom. It also exposes all the water to sunlight and guarantees healthy plant life, which in turn supports healthy fish and animal life.
But salt water is denser than fresh water. (That’s why we can float in it!) So, salt water sinks to the lake bottom and stays there, thus preventing the mixing and turnover essential for a healthy aquatic environment.
The combination of too much phosphorus and salt robs lake water of its oxygen, kills healthy aquatic plant life, and eventually kills or drives out the animals that no longer have food or oxygen to survive. Reducing the amount of these pollutants coming into the lakes could help them recover some much-needed balance.
Students and faculty from the Environmental Studies program at WMU continue to sample and test water in the Asylum Lake Preserve through the year. The canoes sometimes tied to trees near the south side of Asylum Lake aren’t pleasure boats. They were bought with part of a National Science Foundation grant to WMU and are used to take samples from the lake water and the lake bottom.
We are fortunate to have local experts who are learning about our environment and sharing that knowledge so we can preserve the natural gifts that we have in the Asylum Lake Preserve.
Let’s all do our part to keep our lake water clean and healthy.