Spreading a few loads of salt across your driveway is an easy way to ward off your snow woes, and it’s certainly faster than putting in the work behind the shovel. But an increasing body of evidence reveals that the growing amount of residual salt accumulating in wetlands alongside highways and near residential areas is causing long-term damage to wildlife and plant communities both in wetlands and on dry ground.
“We walk on it, we drive on it — it’s pervasive,” says Rick Relyea, an ecologist with Rensselaer Polytechnic Institute, a private university in New York. “It’s really one of the most pervasive contaminants in northern latitudes that we, relatively speaking, know very little about.”
Depending on the type of road salt used to melt ice, the consequences can vary greatly. Road salt can stall the growth of amphibians and trout, as well as kill the zooplankton that provides the base for most aquatic life. It could even affect land creatures who rely on roadside plants absorbing the salt in the soil. Also concerning is the increase in salt levels in wetlands alongside roads treated with lots of salt. When you put too much salt in water, you can profoundly change the freshwater ecosystem to a brinier environment. “It makes it very difficult for everything living in the water,” says Relyea. In cases where public water sources or private wells lie near roads, the extra salt can even be a danger to human health.
