Road Salt
Road salt (sodium chloride) was first utilized within the U.S. on roads in NH in 1938. By 1941 a total of 5,000 tons of salt were applied to highways nationwide. Today, between 10-20 million tons of salt are applied annually. This increase in road salt application is having a negative impact on our waterways, soils, cars, and infrastructure. Lake Champlain alone has seen a 30% increase in chloride levels within the past 10 years.
Road salt lowers the freezing point of ice, allowing it to melt and prevents icy roads to a certain temperature. 15 degrees is regarded as the magic number, below that sodium chloride does not work. While sand costs less then salt, it has negative environmental impacts and is ineffective. Not only is sand easily blown away, it can cause sedimentation to local waterways and carries phosphorus. Road salt is 40% sodium, 60% chloride and may contain ferrocyanide for anti-caking and 5% of the total weight as phosphorus.
Road salt application within our waterways is generally measured in levels of chloride. Road salt is applied to our many roadways, driveways, sidewalks, and parking lots. Following a thaw or rain event, the road salt is flushed into our waterways, lakes and road-side areas. Up to 63% of the road salt applied to roads can be transported by air into the surrounding environment. Studies have shown that between 10-55% of road salt makes its way into groundwater. Road salt accumulates in high concentrations in snow piles beside roads, or that has been plowed from roads. Road salt levels are highest in the spring, but have a lasting impact to groundwater which is shown in high sodium chloride readings within streams in the fall during low flow conditions. Implementing Best Management Practices can not only help budgets, but can protect our natural resources.
