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Salt in our Freshwater

January 3, 2017

Sherry White
"Salt of the earth" means a decent and honorable person. Salt in the water, on the other hand, means a serious environmental issue that's virtually impossible to reverse.

With oceans full of saltwater, the idea of salt as a water pollutant may sound strange.  But salt in freshwater is an entirely different matter.  High salt concentrations can make groundwater unsafe to drink and is toxic to many aquatic plants and animals.

Most of the salt put down on our streets and sidewalks eventually washes down the storm drain and into a nearby lake or stream. A recent University of Minnesota study found that nearly 80 percent of road salt applied ends up either in our groundwater or in lakes, streams and wetlands. Minnehaha Creek is one of many Minnesota water bodies considered impaired for its salt levels.

With the technology at hand, it is just about impossible to remove salt from our waters (or at least too wildly expensive to consider). So the amount of salt in the water only grows over time. With an estimated 730 million pounds of salt applied in the Twin Cities each winter (according to the Minnesota Pollution Control Agency – MPCA), you can see the problem is a big one!

This is concerning for a number of reasons. Groundwater samples from more than a quarter of the monitoring wells in the Twin Cities found salt levels higher than the federal government's guidelines for drinking water. If water becomes too salty, it can't be used for drinking any more, and three-quarters of Minnesotans rely on groundwater for drinking.

No one is suggesting we leave our roads and sidewalks icy.  But many people use more salt than they need. 

Past a certain point, using more salt does not melt more ice, or melt it faster. In reality, salt only works when there is enough snow or ice for it to react with and excess crystals will eventually become a pollutant. It's best to use less than a pound of salt – about a 12-ounce coffee mug worth – per 250 square feet (a parking space is about 150 square feet).

There are some easy ways you can help reduce your salt use this winter: Apply salt or other de-icer before the snow flies, so you will need less later. Shovel regularly (a great form of winter exercise) to minimize ice buildup. Break up ice with an ice scraper before deciding if sand or a de-icer is necessary for traction – you may find that it's not. Use sand instead of salt when the temperature is below 15 degrees. Sweep up any salt that's visible on dry pavement and use it elsewhere or throw it away.

The MCWD and its partners also offer trainings each winter for homeowners, plow drivers, property managers, and others who apply salt in the winter. Learn more about salt.