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Environment & Science

‘Hold the salt’: How the road treatment impacts the Lehigh Valley year-round

Road salt
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While excess road salt can negatively impact the environment, advocates said it’s a balancing act between guarding against groundwater contamination while keeping motorists and pedestrians safe during winter storms.

BETHLEHEM, Pa. — Once road salt gets into the environment, it’s persistent.

“It hangs around. It doesn't really go away,” said Abby Hileman, the Salt Watch coordinator with the Izaak Walton League of America. “Yes, sometimes it does get diluted and maybe washed downstream, but then our neighbors down the stream are affected by it.”

  • A session during the Lehigh Valley Watershed conference last month covered the negative effects of road salt
  • Excessive road salt can contaminate groundwater and corrode infrastructure
  • A typical coffee cup holds enough to salt a 20-foot driveway or 10 sidewalk squares

Hileman’s “Hold the Salt: The Salt Watch Community Science Initiative” was one of the sessions held last month during the Lehigh Valley Watershed Conference at Lehigh University. The ninth of such conferences, it was titled “Endemic Watershed Connections: Place. Preservation. Restoration.” and more than 200 people attended.

Hileman's session focused on the impacts of road salt on the environment, and her work with the Izaak Walton League, through which residents can request a free testing kit to measure the salt levels in their local waterways.

While excess road salt can negatively impact the environment, advocates said it’s a balancing act between guarding against groundwater contamination while keeping motorists and pedestrians safe during winter storms.

But it isn’t just a seasonal problem, Hileman said. Salt Watch monitors near Philadelphia are recording spikes of chloride in streams and creeks year-round.

“Especially during drought events, they tend to have spikes in chlorides during that time because there's less water to dilute the chlorides that might be sticking around in the soil,” she said. “And, unfortunately, there can be some groundwater contamination implications with that too.”

The problem with salt

Sodium chloride, commonly known as rock salt, is an effective and cheap method to melt snow and ice. But it can also negatively impact the environment and residents’ health.

“Road salt can contaminate drinking water, kill or endanger wildlife, increase soil erosion and damage private and public property,” according to the Environmental Protection Agency. “ … High sodium levels in drinking water affect people with high blood pressure, and high chloride levels in surface waters are toxic to some fish, bugs and amphibians.

"Furthermore, excess road salt accumulates on roadside areas killing roadside plants and harming wildlife that eat the salt crystals. Salty roads also attract animals like deer and moose (who love licking up the salt), increasing the probability of accidents and roadkill.”

Large quantities can also be corrosive, affecting cars, trucks, bridges and roads, the EPA notes, costing approximately $5 billion in repairs across the U.S. each year.

However, there isn’t currently a more cost-effective method to keep roads clear of snow and ice.

“CMA, which is calcium magnesium acetate, is one thing that is considered to be a lot more environmentally neutral than chloride is,” Hileman said. “However, the price point is significantly higher … Typically, sodium chloride is the most commonly used type of road salt.

“If that is $70 per ton, a ton of calcium magnesium acetate is $300.”

How much is too much salt?

Hileman said she used to over-salt, and it’s pretty easy to do.

"I've learned that actually a 12-ounce drinking mug — your typical coffee cup — holds enough salt to salt a 20-foot driveway or 10 sidewalk squares, so about two parking spaces. And that's really all that you need."
Abby Hileman, Salt Watch coordinator with the Izaak Walton League of America

“I've learned that actually a 12-ounce drinking mug — your typical coffee cup — holds enough salt to salt a 20-foot driveway or 10 sidewalk squares, so about two parking spaces,” she said. “And that's really all that you need.

“So by shoveling early and often, clearing walkways before snow turns to ice, scattering that salt, using a lot less, you can really cut back on the amount of salt that you're using.”

But there are many people and agencies using salt during the winter — not just residents.

“There's applicators at different levels,” Hileman explained. “Generally, what we have found is that the city, state, local municipalities — they're generally pretty good as far as how much road salt that they're applying.”

This past winter, the Pennsylvania Department of Transportation (PennDOT) used 444,486 tons of salt statewide, according to spokesman Ron Young. The agency’s Lehigh County office used 3,928 tons of salt, and the Northampton County office used 4,867 tons.

It’s a large decrease from last winter, thanks to below average snowfall. During the Lehigh Valley's climatological winter, which runs from December through February, the region saw 4.9 inches of snow. If a dusting from early December is added to the total, the region received just over 6 inches total.

During the 2021-2022 season, Lehigh County’s PennDOT office used 9,784 tons of salt, while Northampton's used 12,939 tons.

“All plow trucks have spreading equipment that allows the operators to adjust the amount of salt being spread which prevents over-salting,” Young said. “The trucks have equipment that provides the operator with air temperatures and road surface temperatures, and that data combined with the type of precipitation, winds, etc. allows them to make real-time adjustments on the amount of salt to spread.”

Philadelphia-area Salt Watch monitors

Geoffrey Selling, a retired elementary science and environment teacher, has been monitoring salinity levels through the Salt Watch program for four years around the Curtis Arboretum and Rock Creek in Montgomery County.

It was May the first time they tested chloride levels, he said, “and the numbers were through the roof.”

“I kind of freaked out,” Selling said. “So what does that mean that we got this much salt coming into this stream, and it's still there in May? The roads haven't been salted since probably early February.”

Since then, Selling and other volunteers have tested area streams each month as part of continuous monitoring.

“What we saw were sky-high numbers right through the year,” he said. “Right through August, when there's not been any road salting for a long time. So then we started asking questions, Why is this?

“Basically, the salt has gotten into the groundwater.”

But Selling didn’t just point to road salting operations as the cause, noting there can be many explanations.

For example, he once noticed a huge pile of salt at a big box retailer. It was uncovered, so every time it rained, salt washed into the nearby streams. Another time, the parking lot of a supermarket was incredibly over-salted, again washing into nearby waterways.

“The other piece of this coin, and it's really difficult, is the whole liability issue,” he explained. “So here's a supermarket. They put down four times as much salt as they need to. But if some nice old lady slips on ice, falls and cracks her head, whoa, the attorneys are gonna be there and they're gonna get hit.

“Whereas, thinking about the frogs downstream is not a priority for a supermarket, or the property manager that rents the store. It’s complicated.”

Extreme spikes in chloride levels is one of the reasons Ryan Neuman started monitoring salt levels in southeast Philadelphia.

“We've seen some levels that are like the saltiness of seawater in some of our sections of streams,” said Neuman, upstream conservation leader for the Tookany/Tacony Frankford Watershed Partnership. “That's not something you can obviously see from looking at the water, but when people hear that they're blown away that a freshwater stream this far inland can have that much salt in it for any period of time.”

Using local testing data, the nonprofit is working to create a comprehensive map to show salt levels in the watershed, he said.

Educating residents and leaders on the problem using data is the first step, but collaboration is needed.

“I think it's tough to say, initially here, what actionable steps that municipalities can take before we learn how much salt they're actually using, and, if there can be cuts, what some of their practices are,” Neuman said. “So that is sort of our next open step beyond education is to start to engage them about their use, so we can be better informed about that.

“Because it's one thing to say use less. But if we don't know how much they use, what their capacity is, those types of issues, how are they supposed to do any better?”