CASNOVIA TOWNSHIP, Mich. — The byproducts of Michigan's winters linger in its lakes.
According to a recent estimate by a New York nonprofit environmental research firm, more than 20 million metric tons of salt are poured on U.S. roads each winter. Come springtime, this attempt to combat slippery highways and byways then makes its way into freshwater rivers and lakes in the form of salty runoff.
"We don't have a good grasp on where the problem is, how extensive the problem is in different places," said Katie Tyrrell, a researcher at Grand Valley State University's Robert B. Annis Water Resources Institute (AWRI).
On Wednesday, Tyrrell and two others from the institute took water samples from Half Moon Lake in Muskegon County as part of a 50-lake, five county study on salt pollution.
"We obviously want our transportation departments to be successful," Tyrrell said. "We want to set them up for success as they go into the winter season and do what they need to do to keep us safe."
It's a balancing act, the researcher says, between the safety of roads and the health of lakes.
If a freshwater body of water turns too salty, its water column can become stratified — separated into distinct layers based on density, driven by temperature and chemical differences — leading to increased algal blooms and "a cascade of other ecological problems."
High salinity can also negatively affect native fish and plant species.
"To me, it's really important to do what we can, to continue to project and preserve our local bodies of water," Tyrrell said.
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As part of the sampling on Half Moon Lake, Tyrrell, along with reseasrchers Mya Harmer and Alexis Porter, drew water samples from one foot below the surface and one foot above the lake bottom.
They also recorded measurements at one-foot increments within the water column.
The study, which includes Lake, Mason, Muskegon, Newaygo and Oceana counties, is funded by a grant from the U.S. Geological Survey in partnership with Michigan State University and will be completed by the end of August.
"This is information that will be necessary to make the decisions that happen from the state down to the local level," Tyrrell said.
