Road salt works. But it is also harmful for the environment.


According to a growing body of research, the chemical is effective at keeping roads free of snow and ice, but it also has harmful consequences.

A truck treats a roadway in Greeley Tribune on Friday, January 7, 2022, as if a winter storm is blowing across the Northeast. Maddie Malhotra / The New York Times

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As blizzards hit the East Coast of the United States this week, transportation officials have deployed a solution to keep winter roads clear: salt.

But although adding tons of salt to the roads makes driving safer in winter, it also has harmful environmental and health consequences, according to a growing body of research.

As snow and ice melt on roads, salt washes into soil, lakes and streams, in some cases contaminating drinking water reservoirs and wells. It has killed or endangered wildlife in freshwater ecosystems, along with high chloride levels that are toxic to fish, insects and amphibians, according to the Environmental Protection Agency.

“This is an issue that needs attention right now,” said Bill Hintz, assistant professor in the Department of Environmental Sciences at the University of Toledo and lead author of a recent research review published in the journal Science. Frontiers in Ecology and the Environment,

“There is a lot of scientific evidence to suggest that freshwater ecosystems are being contaminated by salt, such as by the use of things like road salt beyond a concentration that is safe for freshwater organisms and human consumption. ,” Hintz said.

Road salt is an environmental pollutant.

Hintz said salt has been used to snow off roads in the United States since the 1930s, and its use has tripled nationwide. According to an estimate by the Carey Institute of Ecosystem Studies in New York, more than 20 million metric tons of salt are dumped on America’s roads every winter, and the costs to the environment are increasing.

StillVictoria Kelly, environmental programming manager at the Carey Institute, said little has been done to address the environmental impact of road salt because it is cheap and effective. By lowering the freezing temperature of the water, the salt prevents the ice from turning into ice and melts the already existing ice.

Road salt is made from sodium chloride, the same chemical found in table salt. According to the US Geological Survey in 2020, about 43% of all salt consumed in the United States is used for highway de-icing.

The consequences of inadequately salted roads were seen this week, when a snowstorm on Interstate 95 in Virginia left hundreds of drivers stranded. Officials said the storm began with rain, which washed away road salt and made it difficult to keep the roads clear. The mid-Atlantic states and the Northeast received more snow on Friday.

But environmentalists say the problems related to road salt are becoming increasingly difficult to ignore. Kelly said that in some places, salt deposits in drinking water reservoirs are harming people on low-sodium diets.

A 2018 study of wells in Duchess County, New York, found that sodium levels in wells reached as high as 860 milligrams per liter—much higher than previously thought. Federal and state recommendation This level does not exceed 20 milligrams per liter for people on a very low sodium diet and 270 milligrams per liter for those on a moderately restricted sodium diet.

a different 2018 The study in the journal Environmental Science and Technology showed that 24% of private drinking wells in New York were contaminated with salt used on the streets. According to the Centers for Disease Control and Prevention, about 15% of people in the United States get their water from private wells, while the rest rely on community water systems.

More counties and states are rethinking the amount of salt they use because of the associated costs. Last month, New York Governor Kathy Hochul announced appointments to the Adirondack Road Salt Reduction Task Force, established to review road-salt contamination.

“I have no doubt that this group of individuals will work tirelessly to save our state from the adverse effects of road salt,” Hochul said. “We look forward to seeing this group eventually grow and make progress in preventing further pollution to our waterways and our environment.”

There are consequences for wildlife as well. Hintz said their review showed that high salinity levels in freshwater ecosystems have already led to a decrease in the abundance and growth of freshwater organisms and a reduction in their reproductive output.

According to EPA estimates, road salt also damages vehicles and bridges, costing the United States $5 billion in annual repairs. The AAA recommends that drivers wash and sanitize their vehicles regularly during the winter to reduce the effects of road salt and to limit driving when salt and other de-icing chemicals are at their highest concentrations.

In the UK, the Salt Association states that salt is the cheapest form of de-icing material and has the least environmental impact when used responsibly. “As with all highway maintenance activities, winter road maintenance has environmental impacts,” the organization said in a statement. “Highway depots, disperse vehicles and de-icing agents all contribute, but with good management, this burden can be reduced.”

Alternative methods can reduce the loss.

While there is no perfect solution to this issue, there are alternatives that can significantly reduce salt use without compromising driver safety.

According to the Carey Institute, one method involves treating roads before storms with a salt saline solution, which can reduce the amount of salt used by 75% while keeping roads safe. Building better salt storage sites can also reduce waste.

Some counties, including Jefferson County, Wisconsin, have already made the changes. County Highway Commissioner Bill Kern said the switch to the saline solution has enabled the county to cut its salt use by up to 60% from 2018 without increasing the number of accidents. By using less salt, the county has reduced its overall costs for winter maintenance of state and county highways by 20% since 2018, saving about $1.6 million, Kern said.

Over the past decade, some states, including Rhode Island, have passed laws aimed at reducing road salt use and implemented increasingly salty solutions on roads in the winter, but environmentalists say more needs to be done. .

Although engineers have developed better alternatives, they have not been widely implemented because they require upfront costs to purchase equipment, Kelly said.

“It will save us money, and it will help save our freshwater,” she said, “because of that legacy effect, it will take a really long time to see the impact of the steps we take.”

This article originally appeared in the new York Times,