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Hold the Salt

Researcher Tracks Human Cost of Keeping Roads Ice-Free

By Chris Carroll


Illustration by Gabriella Hernandez

Illustration by Gabriella Hernandez

University geologist Sujay Kaushal was waiting to testify in Annapolis several years ago about problems caused by the salt spread each winter on Maryland roads when laughter interrupted the hearing. It was directed at the state lawmaker who’d raised the seemingly outlandish topic.

“People were like, ‘What is this guy talking about—salt?’” says Kaushal, an associate professor in UMD’s Earth Systems Science Interdisciplinary Center and the Department of Geology. “But people wouldn’t be laughing today.”

For more than a decade, Kaushal’s research has documented rising salinity in surface water in Maryland and elsewhere, primarily the result of road salt. One of the consequences he warns about—corrosion of water pipes caused by the chemical breakdown of sodium chloride ice melter—reared its head in 2015 in Flint, Mich. There, as many as 12,000 children ingested excess lead in drinking water, putting them at risk for damage to their developing brains and nervous systems.

Although news coverage focused on testing cover-ups, political recriminations and the potential health effects, salt contamination in the Flint River that caused corroded pipes to leach lead into tap water was the source of the problem.

Here’s what’s really scary: Countless miles of aging municipal and residential water pipes nationwide are at the same risk, Kaushal says. Even he and his neighbors in suburban D.C. experienced brown water flowing from their taps in 2015, the result of salinity spiking in the Potomac River.

“It hit me that I have a small child in the house, and there could be elevated levels of harmful metals in the water,” he says.

In addition to danger from corroding pipes, saltier water carries other risks. It can compromise entire ecosystems by harming aquatic life in rivers and streams, and it can injure people with sodium-sensitive health conditions like kidney disease.

“When I worked for Baltimore City, I received calls a couple times from local hospitals with concerns about the level of sodium in drinking water because of what it could do to patients on dialysis,” says Bill Stack, deputy director of the nonprofit Center for Watershed Protection and former manager of Baltimore’s surface water protection program.

Stack began monitoring chloride in water in the early ‘80s, believing it was linked to failing septic systems. But as he watched the levels increase by more than 200 percent in two decades, the finger of blame swung toward the increased road salting that followed new development in Maryland.

Stack was a co-author on Kaushal’s seminal 2005 paper that showed rising water salinity across the Northeast. And he’s watched a steady stream of science papers expand the findings in new directions, such as the effect of acid rain on salinity.

“He’s one of the leading researchers I know of in using science to address practical issues,” Stack says. “His research is very applied, and he’s on the cutting edge.”

Limiting the salt won’t be simple, particularly during a winter like that of 2013–14, when frequent snowfalls prompted road crews to spread nearly 500,000 tons in Maryland. Safety requires some road salting, Kaushal acknowledges, but limiting the practice to what’s strictly necessary could help reduce environmental and health damage.

Still, even in progressive Maryland, where the state is studying methods to implement some of the limits that lawmakers previously laughed at, the latest research shows that water salinity continues to rise.

“I think salinization will continue building to a crisis level,” Kaushal says. “People are starting to pay attention—now it has to reach a point where there is a political will to address it.”

Maryland Today is produced by the Office of Marketing and Communications for the University of Maryland community on weekdays during the academic year, except for university holidays.