The environmental impact of road salt

Over the past week, snowstorms have hammered large swathes of the United States. From New York and New England in the north to D.C. and North Carolina down south, winter weather is making the start of 2022 a memorable time for many. 


As is the case any time a winter storm rolls around, most transportation officials are clearing the roads the way they always do — by pouring tons of salt on top of them. However, while effective at making driving conditions safer, the environmental impact is less than positive. 


Why salt? 

Transportation officials in the United States have used salt to clear away ice and snow on roads since the 1930s. As cities, suburbs, and rural communities grow, salt use has grown with them. Today, over 20 million metric tons of salt get poured on roads across the country each year. 


Salt is effective at melting ice and snow because it lowers the freezing point of water. Water usually freezes at 32 degrees Fahrenheit, but salt can cause that number to drop by ten or more degrees. If a snowstorm hits an area and the outside temperature is 30 degrees Fahrenheit, salt will therefore melt the ice or prevent water from freezing in the first place. 


The environmental impact  

While salt is a cheap and easy way to eliminate ice and snow, it leaves a fair amount of environmental damage in its wake.


After salt washes off roads, it often ends up drinking water reservoirs. In some states, sodium levels are as high as 860 milligrams per liter — exponentially higher than the 20 milligrams per liter recommendation given by health experts to people on low-sodium diets. 


Besides clogging up water reservoirs, salt also corrodes many of the objects it comes into contact with. Besides your expensive winter boots, this also includes public infrastructure. Each year, salt-related corrosion causes more than $5 billion in damage to roads, highways, and vehicles countrywide. 


Likewise, salt also impacts freshwater ecosystems. When salinity levels get too high, it hampers organisms' growth and reproductive outputs. As many freshwater environments are delicate and don’t respond well to fluctuations, higher salinity levels can lead to massive changes. 


Too good to get rid of

While salt may be damaging to the environment, it’s not likely to disappear from roads, highways, and sidewalks anytime soon. Its effectiveness makes it a virtual necessity, especially in regions like the Northeast that often experience lots of ice and snow. 


Last week, a snowstorm stranded hundreds of drivers in their cars on Interstate 95 in Virginia. What made that storm so deadly? The rain that came before it washed away all the salt transportation officials had laid down in preparation. 


Had salt been on the roads, it’s likely that people wouldn’t have been stuck in their cars for hours on end. 


Finding a more sustainable solution 

There aren’t any perfect alternatives to salt that can provide the same benefits at a similar price point. That said, many communities around the country are finding ways to do better. 


Jefferson County, Wisconsin, for instance, now uses a salt brine solution as opposed to pure salt pellets. This cuts the amount of salt used by more than 60% and lowers the amount of money spent on winter maintenance by around $1.6 million.


As the harmful environmental effects of salt become clearer, environmental experts hope that more states will switch to the more sustainable salt brine solutions. If nothing else, switching away from pure salt is also a great way for regions to save money!

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