It was March 27. Although just a week prior Michigan was enjoying 60+ degree temperatures, the weekend rolled in with 20-30 degree temps and another late dusting of snow. It wasn’t a lot of snow for Michigan, but the damage was done. While out running errands it was difficult to ignore the white chalky look to the road. The county had indeed salted the roads.
Luckily on the west side of the Michigan state, the salt usage is a fraction of what is used in downtown Detroit. There, I-75 in the winter would at times turn the freshly-laid black asphalt into a milky white from the salt deposited over the season. Understandably it is for safety as snow, sleet and ice make commuting a nightmare in the city, but it was also laid for convenience. But is the salt too much? And a question that not enough ask is, “what are the ecological repercussions of using this amount of salt?”
According to recent data provided by the Huron River Watershed Council, surrounding freshwater rivers and tributaries are showing excessive levels of salinity – saying one sample had 42 times the level of salt that people can taste (that level is 30 milligrams per liter, the sample was 1,300 mg per liter).
The samples for this study were collected around this same time of year in 2015. At this point in March, in Michigan, there might be one or two snowfalls left in Mother Nature’s planner, but otherwise, the state has seen its fair share of snow. And yet the salt was undeniably at problematic levels.
From The Detroit News on the impacts of these heightened levels of salinity:
“Ecosystem degradation is the biggest impact of high chloride concentration,” said Andrea Paine, a Huron River Watershed Council watershed planning associate. “There’s threats to environmental health and river health in general, including impacts to aquatic macroinvertebrates, fish and other aquatic species including plant life.”
Salt can even change the look of wetlands, stream banks or lake shores.
“Oftentimes, that can lead to the increased presence of plants such as cattails and weed grass that do tend to thrive in salty environments,” Paine said. “As we see these higher chloride concentrations, there is this modification of the ecosystem toward species that thrive in these saltier conditions.”
Late last year, another study was published regarding the salt loads in Lake Michigan, and the literature is not very promising if you can get past the scientific explanation (emphasis mine):
Chloride concentrations (an anion common to most salts) in the Great Lakes have risen over the last two centuries, from estimated concentrations ~ 1–2 mg L−1 in the 1800s to present day concentrations > 10 mg L−1 in Lake Michigan, Erie, and Ontario (Chapra et al. 2009). Lake Erie and Lake Ontario had large declines in chloride concentrations beginning in the 1980s following the introduction of the U.S. Clean Water Act (Chapra et al. 2009), whereas Lake Michigan steadily increased in chloride during this time.
For Lake Michigan, with a water volume of 4.918 trillion m3, it would take ~ 5 Tg (1 Tg = 1 million metric tons) of salt to raise the salinity by 1 mg L−1. Based on the estimated annual loading of road salt in the Lake Michigan basin, this could be accomplished in 2–3 yr (Fig. 1a; Bock et al. 2018). From 1980 to 2020, chloride concentrations in Lake Michigan increased from ~ 9 to ~ 15 mg L−1 (Fig. 1b). This annual increase of 0.125 mg L−1 equates to ~ 0.625 Tg of additional chloride added to Lake Michigan per year.
I know, there’s a lot of numbers and scientific jargon in there. But the important information to take in here is the fresh water resources, just in Michigan, have a lot of salt in them, and scientific projections show that the water, and crowning Great Lakes waters, are indeed getting, and will continue to get saltier.
The study also considers that some of the salinity is also due to water softeners used in communities with well water access and some industrial additions. However, road salt is the major offender, and this isn’t the first time its use has affected Michigan residents.
Back in 2017, a class action lawsuit was filed against General Motors by a community located near the company’s Milford Proving Grounds, in Oakland County. The lawsuit claims the General knowingly contaminated the water supply, allegedly via high levels of sodium and chloride.
GM continued to deny they were cause to the salty water issues their neighbors were facing. However, a study in the late ‘90s confirmed the sodium and chloride levels not only exceeded the Environmental Protection Agency’s limits, but the Michigan Environmental Quality Department did find that those elements appear to have come from GM’s Proving Grounds. When GM then installed wells to sample groundwater... I’ll let our article in 2018 explain:
Sampling from the wells showed groundwater with elevated levels of sodium and chloride “likely have migrated off the Proving Grounds,” according to the lawsuit, far exceeding federal limits set for each.
The results indicated, the suit continued, “groundwater flow in the southwest corner of the Proving Grounds is to the south and southwest,” meaning in the direction of the Oaks subdivision.
“The first time that any of our clients knew, or had any reason to know that this was coming from General Motors—and was not a natural phenomenon and was not coming from across just salt from the street, or salt in the ground—was in 2014, when General Motors sent out a notice to everybody through the MDEQ that this was a runoff issue,” the plaintiffs’ co-counsel, Alex Memmen, told Jalopnik.
While salt, or more specifically chloride is a naturally occurring mineral, it isn’t something easily removed from the environment. It remains in the soil, the state’s rivers, waterways and Great Lakes, and even your ground wells.
In this case, that salt remains a constant pollutant for these Milford residents, who had to make considerable life adjustments with osmosis tanks or gallons upon gallons of bottled water being delivered weekly, just to live near a place that utilized hoards of salt on their roads.
GM has been said to have reduced their road salt use in recent years. The Detroit News explained that Oakland County has also made adjustments to reduce their use of road salt, and implementing other use practices to help lessen the salt sprawl. One change was buying new trucks that adjust salt release in conjunction with the speed the truck is going.
The changes are somewhat significant (Oakland reducing road salt use by 20,000 tons), but makes for just a minor step in reducing the salt load in Michigan’s fresh waters and communities. According to Michigan State University Research Assistant Professor Anthony Kendall, who worked on the December study on the Great Lake’s salinity, the concern is that the road salt will continue to increase chloride to a level where it starts harming lakes and wetlands. That level — around 1,000 milligrams per liter — could drastically affect native habitants of Michigan’s ecosystems.
Some good-ish news is that while the Great Lakes are getting salty, they’re not quite to sea water levels at this time:
Lake Michigan has about 15 milligrams of chloride per liter, Kendall’s study found. He estimated Lake Erie contains twice as much. Sea water has roughly 35,000 milligrams per liter, or at least 1,000 times more than Lake Erie.
While the Great Lakes potential of becoming salty oceans in the future is definitely a concern, I know motorists (myself included) in Michigan and the Midwest would also be in favor of a lesser-salty future. I mean, really, let’s just use less salt on the roads.