A three-story-tall gate creaks open, and reveals a warehouse filled to the brim with brown crystals. It’s a mountain of rock salt.
“We filled this shed this past week,” says T.J. Shea, Cambridge’s superintendent of streets. Shea is what some might call a “snow fighter.” It’s his job to keep roads dry all winter using this salt at Cambridge’s Public Works facility in Danehy Park. There’s more than a thousand tons of salt here – equal in weight to about nine blue whales. But Shea says it won’t last long.
“This is a couple of storms worth, depending on the event and the duration,” he says.
That’s a lot of salt, and by the end of the season, almost all of it will end up in our rivers and streams, where it can harm the health of freshwater ecosystems. Now, as local researchers assess the impact on local waterways, towns like Cambridge are trying new ways to use less salt while keeping the roads safe.
“It’s such a pervasive issue,” says Richard Chase, an environmental analyst with the Mass. Department of Environmental Protection. “It really needs a multitude of solutions.”
As snow dissolves, road salt washes into storm drains, through the stormwater system, and out of pipes into the nearest water body, says Andy Hrycyna, a scientist with the Mystic River Watershed Association.
“Road salt is known to have negative effects on freshwater ecosystems,” he says.
One 2014 study from the U.S. Geological Survey found that high concentrations of road salt in waterways in places like Wisconsin, Illinois, and Colorado was having toxic effects on aquatic plants and animals.
Hrycyna regularly visits testing sites at Alewife Brook and other locations, to try to figure out what’s happening in Massachusetts. He calls what he’s doing “guerrilla water quality monitoring.”
Here’s Hrycyna’s routine: He scrambles down the steep hill from Alewife Brook Parkway to the stream, careful to not to slip or get poked in the eye by bushes. He then hauls a cinderblock out of the stream — it’s connected to a digital water testing device that he hooks up to his laptop. The computer spits out a graph almost immediately.
“You can see this spike in the black line,” Hrycyna says, “which essentially shows that the salt concentration in the water for a period of a day or longer went up two and a half times.”
Hrycyna attributes this particular spike to a rainy day earlier in the week that washed all the nearby road salt into the brook.
Andy has tracked the brook’s salt levels for a year now, and this is just another data point that he hopes will spark an important conversation in and around Boston, about whether we can reduce the use of road salt “in some smart, collective way.”
Richard Chase, the environmental analyst at MassDEP, says researchers have known about the problem for a decade now, and salt reduction is a significant concern in cities where there is snow and ice. That’s not just because of salt’s impacts on aquatic organisms, but also because it can get into our drinking water– which can impact our health and create higher treatment costs for states to get the salt out.
“It’s a problem that doesn’t have easy solutions,” Chase says. “It’s not going away. We need to have safe roads.”
Katharine Lange, a policy specialist with the Massachusetts Rivers Alliance, agrees that there’s no quick fix. “We don’t have an alternative that’s fantastic and that we can use at scale,” she says, adding that pilot projects are a “great option.”
One rural community in Wisconsin, for example, has found success using liquid cheese brine — a dairy industry byproduct — to fight off ice.
Closer to home, a pilot program in Cambridge is using a brine mix of water and “solar salt,” instead of that mountain of rock salt mentioned earlier. Where rock salt is mined, solar salt is purified in the sun, which Shea says makes it cleaner and easier to mix into brine.
“We are saving salt, we’re saving resources, we’re saving our environment,” says Shea.
Shea stores his brine in massive water tanks just outside the rock salt warehouse. Brine works the same way as the rock salt – trucks pour it on the road before a storm, and then it melts snow that hits the ground. But brine uses a quarter less salt than the standard rock salt, Shea says.
And it’s cheaper, he says. “We make it ourselves, so there’s savings that way.”
Shea started using brine in 2019 after seeing its success in nearby towns like Newton and Wellesley. This year, brine will de-ice a third of Cambridge’s streets. Shea hopes to raise that number to 100% sometime soon, but he needs more trucks equipped to pour the brine.
Until then, residents will continue to hear the familiar crunch of salt with their snow.
This article was originally published on WBUR.org.
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