Road salt: How much is too much?
LANSING — Volunteers in Gaithersburg, Maryland, are fighting road salt pollution with catchy sayings painted on snowplow blades.
The group is in the hometown of the Izaak Walton League, a national environmental conservancy that created a nationwide program to monitor chloride levels and advocate for reduced use of road salt. The group has recorded high chloride readings in cities across the Midwest and the Northeast, with the highest concentrations in Michigan.
Road salt contains chloride, a toxic compound that dissolves in water. When it’s applied to icy surfaces in the winter, it can drain into streams and lakes.
After receiving Salt Watch test kit results, the Izaak Walton League compiles the data into an interactive map showing chloride levels at the test locations.
Michigan’s high levels are due to a combination of factors, said Samantha Briggs, the program’s director.
The metro Detroit area has a lot of paved surfaces that increase water runoff, Briggs said. “The salt has nowhere else to go.”
Michigan’s streams also have alarming chloride concentrations because of its winter climate. “The constant cycle of freezing and thawing leads to high road salt usage,” Briggs said.
Salt Watch’s data set is limited, and many volunteers have submitted readings from Michigan.
It may only appear the state has the worst chloride problem, according to Briggs. “We have a lot of information from Michigan in particular. We’re always looking to expand.”
Salt Watch has a number of partner organizations in the state, including the Outdoor Discovery Center. The Holland conservancy group is prioritizing the issue along the state’s Lake Michigan coast.
The center’s watershed manager, Kelly Goward, has been monitoring salt levels in lakes and streams near Holland over the past couple of years. The concentration in one local stream measured 290 parts per million in November, which is considered toxic.
Measurements from a 2021 study show that Lake Michigan’s salt content has risen up to 15 times its natural level since the 1800s, but the effects of these high levels are only now being understood.
“It’s one of these things people have been focusing on recently,” Goward said.
Salt Watch was created because of rising concern about salt’s adverse effect on ecosystems across the country. “Salt can desecrate the environment,” said Abby Hileman, the program coordinator.
Chloride can kill macroinvertebrates and affect natural processes such as seasonal lake turnover. It’s also difficult to filter out of drinking water, and it corrodes metal pipes, potentially exposing people to heavy metals like lead.
“Once salt is in the environment, it never leaves,” Hileman said. “It could cause something like the Flint water crisis.”
The Outdoor Discovery Center is looking for solutions, but it understands there needs to be a balance between keeping waterways clean and winter roads safe.
“We need to ask ourselves what scale is appropriate to melt ice,” Goward said.
The group encourages municipalities to cut down on road salt and to put it down only where needed.
Alternatives have also been considered across the Great Lakes region, Goward said. One popular alternative is salt brine, a liquefied form of road salt with less chloride that acts faster.
“Most alternatives aren’t really realistic,” Goward said. Brine, calcium chloride and even beet juice are proposed to de-ice roads, but they cost more to store and purchase compared to road salt.
Many of Salt Watch’s partners focus on public education and teaching best practices to manage road salt.
“We want people taking ownership of their ecosystem, we want them to say, ‘This is my stream,'” Hileman said.
Salt Watch has encouraged its volunteers to call for a reduction in road salt use, and some have helped make changes on a legislative level.
“Seeing people advocate for themselves is big, it’s really empowering,” Briggs said.
The Salt Watch program offers free water sampling kits to environmental organizations and provides funding and road salt education for outreach programs.
“I want my job to be obsolete,” Briggs said.
Daniel Schoenherr reports for Great Lakes Echo.