Humans have used salt for centuries as a seasoning, a preservative, and even as currency. But one of its primary uses may surprise you. The #1 use for salt in the United States is road de-icing. According to the United States Geological Survey’s 2020 Mineral Commodities Report, 43% of salt used in the US in 2019 was put on our roads to melt snow and ice during the winter.
This adds up to a big problem, because the 42 million tons of salt we put on our roads doesn’t stay there. Every bit of salt put down on the road eventually ends up dissolved in melting snow or rain and runs into our lakes, rivers, and groundwater, which puts freshwater ecosystems at risk. Once salt gets in the water, treatment options are limited and costly. Additionally, the salt itself is expensive and carries a big price tag.
So why do we even use salt? Well, it is an effective way to keep our roads and sidewalks ice free – at least above 15°F. Above 15°F, salt mixes with snow and ice and raises its freezing point, keeping things liquid. Below this temperature it cannot do its job and ends up accumulating in clumps. When it gets cold, it is best to switch to a different de-icer or use sand for traction.
The biggest problem with salt-use is over-application. Using salt when it will not work or simply putting too much down does not increase safety, instead, it puts our freshwater resources at risk. And in most circumstances, not that much salt is needed. Over-application can be avoided by lightly scattering salt and leaving 3” of space between the crystals.
Experts taken from WI Salt Wise Partnership (https://www.wisaltwise.com/documents/Linnea-s-Article---WI-Salt-Awareness-Wk-2021.pdf)
Photo credit Banks Photo.