Winter Road Salt Raising Salinity of US Rivers & Lakes

Snow falls on the Brooklyn-Queens Expressway. Photo by Amanda Ottaway.

(CN) – As wintry weather settles in across the United States, snowplows take to the streets spraying salt in order to make the roads safer from ice. Those snowplows, however, are also endangering our water supply, according to researchers.

Freshwater sources like lakes and rivers are becoming saltier, according to a new study released Monday by researchers from the University of Maryland. The biggest culprits appear to be deicers and fertilizers making their way into ever decreasing waterways used for human consumption.

The study looked at more than 50 years of data at 232 U.S. geological monitoring sites, finding concerning increases in salinity that may affect water supplies in the future.

“We created the name ‘Freshwater Salinization Syndrome’ because we realized it’s a suite of effects on water quality, with many different salt ions linked together,” said Sujay Kausha, geology professor and lead author in a written statement. “We didn’t know that before. Many people assume that when you apply salt to the landscape it just gets washed away and disappears. But salt accumulates in soils and groundwater and takes decades to get flushed out.”

Residents of Flint, Michigan, already know about the dangers of salinization. The salty water from Flint River corroded pipes and introduced lead into the city’s water supply. The researchers suggest local governments should oversee replacement of older pipes that could cause further contamination.

“The trends we are seeing in the data all suggest that we need to consider the issue of salt pollution and begin to take it seriously,” Kaushal said. “The Environmental Protection Agency does not regulate salts as primary contaminants in drinking water at the federal level, and there is inconsistency in managing salt pollution at the local level. These factors are something communities need to address to provide safe water now and for future generations.”

While table salt is most commonly used by snowplows, researchers said that a combination of other minerals in various salts, such as potassium and calcium, also contribute to damaging freshwater sources.

“These ‘cocktails’ of salts can be more toxic than just one salt, as some ions can displace and release other ions from soils and rocks, compounding the problem,” Kaushal said. “Ecotoxicologists are just now beginning to understand this.”

According to Kaushal, a saltwater mixture could be more efficient for deicing roads than current methods, as well as less damaging to the local freshwater supply.

“Also, not all salts are created equally in terms of their ability to melt ice at certain temperatures,” Kaushal said. “Choosing the right salt compounds for the right conditions can help melt snow and ice more efficiently with less salt input, which would go a long way toward solving the problem.”


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