Safer winter roads but at a cost to water quality
By Stacy Gittleman
Rock salt on the roadways can reduce accidents by up to 80 percent. According to the most recent state environmental reports, instate road salt use has doubled since 1975, although road agencies in Michigan have reduced salt application rates per lane mile in recent years. Even with these reductions, when snow and ice melt, the salt that was applied to paved surfaces washes into wetlands, lakes and streams through stormwater conveyance systems. The salt from managing winter storm events combines with other sources of salt from water softening backwash and industrial discharges and drains into ground and surface water, resulting in concentrations that eventually will adversely impact the quality of Michigan’s waters.
High sodium levels in drinking water can affect people with high blood pressure, and high chloride levels in surface waters are toxic to some fish, bugs and amphibians.
As we head into the summer, a time when we enjoy the state's water natural resources for fishing, swimming, canoeing and other recreational activities, it's important to keep in mind that the quality of that water in the summer, and year-round, has a lot to do with how the thousands of miles of roads are winterized.
According to environmentalists, academics and government officials interviewed, the Great Lakes states sit on 20 percent of all of the world's freshwater. Added to that, Michigan possesses some of the greatest salt deposits in the world, thanks to the remains of a vast, prehistoric subterranean sea. According to the Detroit Salt Company, rock salt in Detroit was discovered in 1895, and by 1914, the mine was hauling up 8,000 tons of rock salt per month through a 1,160-foot shaft, an engineering marvel at the time. The salt was mainly used for the leather and food processing industries. Today, the mine still exists at 12841 Sanders Street in Detroit. The mine spreads out over more than 1,500 acres and has over 100 miles of underground roads and is a major producer of ice melting products for North America.
Because of this natural resource, Detroit was one of the first large cities to use rock salt to winterize its roads. By 1966, Michigan used 150,000 tons of salt per year, and by the 1990s, that amount tripled. Currently, Michigan uses nearly 500,000 tons of rock salt each winter, according to the Michigan Department of Transportation (MDOT).
Beyond Detroit, the dried-up sea, known geologically as the Michigan Basin, stretches in an underground landmass larger than the state’s Lower Peninsula. Because of these vast underground salt deposits, what is happening now is that when the underground aquifers are over-pumped, salty briny water comes to the top and infiltrates some drinking water, getting into the state’s tributaries that feed into Lake Michigan, according to researchers.
A joint study from Michigan State University and the University of Wisconsin-Madison examined chloride levels from 235 of the 300 tributaries that feed into Lake Michigan from samples taken July 10-15, 2018. Traditionally, Lake Michigan naturally contains one milligram of chloride – a mineral which makes up 60 percent of the molecular mass of sodium chloride (NaCl) per liter.
Researchers concluded that because of decades of using rock salt to winterize roads, among other sources of use the mineral, that level of chloride has steadily but gradually climbed up to 15 milligrams per liter. Comparatively, oceans contain 35 grams of salt per liter. The study stated it would take one million metric tons of salt to raise the salinity of the lake by one milligram per liter. Since the 1800s, chloride concentrations in Lake Michigan have been rising from around one to two milligrams per liter to over 15 milligrams per liter by 2020. The study demonstrated that Lake Michigan’s tributaries are dumping 1.08 million metric tons of chloride into Lake Michigan, and estimated that it would take about five million metric tons of salt to raise the lake’s salinity by one mg per liter, which could happen in one to three years from the time the study was conducted.
Anthony Kendall, associate professor at MSU’s Department of Earth and Environmental Sciences, and one of the authors of the study, said while this increase in salinity is troubling, it is not happening fast enough to make Lake Michigan’s 4.918 trillion gallons of water as salty as the oceans.
"This study was not intended to be like a 'barn-burning three-alarm fire warning,'" cautioned Kendall. “We are not putting enough salt on our landscape that will make the Great Lakes as salty as the oceans, because the volume of Lake Michigan is just so huge. The Great Lakes are fresh and will remain fresh, but they will continue to get saltier because we are using salt at a far faster rate than can be flushed out of the Great Lakes system. It is accumulating in our groundwater and our streams and wetlands – everywhere that water is stored. Salt, and how we use it, is something that we need to get a handle on now because our actions have a very long legacy.”
Kendall continued: “Increased levels of salt will in time cause disruptions and problem hotspots in fragile ecosystems which depend on low salt levels to thrive. What’s needed is to further understand local conditions in certain areas along Lake Michigan’s lakeshore that are being negatively impacted by increased chloride in the water.”
Looking forward, Kendall’s graduate students are now compiling data from water samples taken from Lake Superior.
Kendall explained that half of the water that flows into the Great Lakes comes from groundwater streamflow and the other half percolates into the ground from stormwater runoff, eventually getting discharged into surface waters such as streams and rivers. When water from Michigan’s underground aquifers is over-pumped, it pulls salty water to the surface, which will discharge into surface waters like streams and eventually rivers. But that too will take a long time to reach the Great Lakes.
“It’s hard to visualize, but groundwater flows at a very slow rate,” Kendall explained. “For instance, it can take 30 years for groundwater located 1,000 feet from a stream to reach that stream due to the thickness of our aquifers. Whatever salt we put on our roads or comes out of our septic tanks is going to be in the groundwater for a very long time. Salt readily dissolves into water. It takes expensive, energy-intensive methods like reverse osmosis to remove it. So, there is cause for concern as salt levels in our groundwater gradually build up. We need to take action now to do a better job using this vital mineral, so we don’t cause ourselves more trouble in cleaning it up in the future.”
The Michigan Environment Great Lakes and Energy’s (EGLE) Water Resources Division has been monitoring chloride and sulfate levels in the state’s surface waters since 2005. In 2019, EGLE developed water quality standards that quantified acceptable and dangerous levels of chloride in surface waters. Numerical values vary and reflect the amount of time wildlife could be exposed to effluents of chloride or sulfide before severe harm could occur.
Acute chloride levels (over 640,000 parts per billion) pose threats to the mobility and survival of aquatic flora and fauna, and chronic chloride levels (150,000 parts per billion) are more optimal for species survival, growth and reproduction. Respectively, EGLE has set acute sulfate levels at 1,200,000 parts per billion and chronic levels at 370,000 parts per billion.
In February 2021, EGLE enacted its Chloride and Sulfate Water Quality Values Implementation Plan and added the requirement of municipalities and other entities to incorporate documentation of chloride and sulfate values in its surface waters as part of its National Pollutant Discharge Elimination System (NPDES) Permit Program. According to the plan, these numeric values for chloride and sulfate provide a long-overdue benchmark for the continued protection of aquatic life. With the inclusion of chloride and sulfate in its water quality assessment management, all municipalities applying for an NPDES permit must now include measurements and reports of these substances. The permit will specify the sample type, analytical method, and quantification level that shall be used for the collection and analysis of chloride and sulfate.
In managing levels of chloride and sulfate, new additions to NPDES permits include requirements such as implementing best management and good housekeeping practices, source reduction practices, dilution of higher concentrations under USEPA regulations listed in the Clean Water Act, and employee education.
"Developing those water quality values was truly the jumping-off point for us in the state to educate the public and county and local governments as to what salt applications were doing to impact our environment, aquatic life and water quality,” said Kevin Goodwin, an aquatic biology specialist within EGLE’s Water Resources Division that leads EGLE’s biennial water quality reports. “These are quantifiable values that states like Minnesota and Wisconsin have already had in place. Once we developed these values, which are based on years of toxicological information, they provided concrete thresholds that EGLE could better understand where there might be problems around the state. We could also help our current NPDES permittees in the state understand what their water quality is like and whether additional actions are needed.”
The NDPES also regulates the Municipal Separate Storm Sewer Systems (MS4) program, managed by EGLE environmental quality specialist Christie Alwin. MS4 includes examining stormwater and snowmelt runoff in urbanized areas.
Alwin explained that under this program, before any municipality can apply any deicing application on its roads, EGLE requires municipalities to report its strategies for salt application, storage, and after-season requirements such as equipment cleaning and maintenance as well as street sweeping to remove residual salt from the roads. EGLE requires any municipalities which owns and operate roads, as well as county road commissions and MDOT, must hold a permit under this program. As it is difficult or next to impossible to remove salt once it is dissolved in waterways, programs such as the MS4 are a way for EGLE to focus its efforts at the beginning of the salt application cycle.
“Michigan is unique in that we have a statute that specifically addresses salt as a polluting material,” said Alwin. “We begin regulating a salt storage capacity at five tons or more, which if you are a road agency, or even own a shopping mall, you reach this threshold very quickly. EGLE has specific self-storage requirements. Careful salt application begins with properly calibrated equipment and moves forward from there to avoid excessive salting. If there was an accidental release of excessive salt, it is easier to clean it up if the municipality can pinpoint the spill to a particular location on a road. Once the salt has moved on from its location on the road, there can be no remediation efforts at that time. That’s why we are focused on the beginning of the salt application process.”
Out in the field and reporting her findings back to EGLE’s Goodwin is Sally Petrella, a longtime monitoring manager with Friends of the River Rouge. A trained biologist, over the last three years Petrella and a team of citizen scientists have been working off chloride benchmarks set by EGLE to measure the mineral’s levels in different sections of the Rouge watershed to see how they correlate with populations of wildlife such as the mayfly, the rare red side minnow, which makes it's home exclusively in the Rouge watershed, and especially the humble stonefly.
Overall, Petrella said the most important indicator of the health of the Rouge River watershed – which in part comprises the inland lakes tributaries and streams in Bloomfield Township and Birmingham – is the quality populations of aquatic and amphibious and native plant species.
Beginning in the winter of 2020, Petrella said the Friends of the Rouge participated in a national winter saltwater program run by the Izaak Walton League, one of America’s oldest conservation organizations, to understand how chloride levels were impacting the water. They collected water samples from 30 locations along the Rouge using test kits provided by the Walton League and measured the water quality based on EGLE’s new standards, but quantified findings in parts per million, rather than parts per billion. They coupled this data with their work monitoring populations of the stonefly, which lays its eggs in the water in January, at the height of winter salting season.
The citizen scientists first tested for chloride levels in the winter of 2020, and then again in the winter of 2021. Many of the 2021 samples came back at levels exceeding 320 parts per million, and others showed readings of over 150 parts per million of chloride, a level considered to have a chronic long-term impact on freshwater aquatic life. Areas of concern included Tonquish Creek in Wayne County, the main branch of the Rouge that runs in Firefighters Park in Troy, and Murphy Creek, which runs along the property of The Roeper School in Bloomfield Hills.
"We developed a score for bug count and also kept numbers of salt levels on these sites, and what we observed that there was a clear correlation that sites with higher salt levels had lower scores for numbers of stoneflies, as well as mayflies,” said Petrella.
Petrella also remarked that after the dry winter and spring of 2021, “In the winter of 2021, there was a drought, so there was not much flushing of the waterways with rain or snowfall,” she recalled. “We did see elevated salt levels and low counts of stonefly, which we thought would dissipate over time. When we came back to monitor levels in the spring, we were surprised to find continued elevated chloride levels.”
Dry conditions continued into the spring of 2021 until the deluges of that summer. When her volunteers returned to the same sites in the fall of 2021, they expected that all the heavy rain events from that summer would have flushed the Rouge of some of its chloride levels.
“We went back to these sites in the fall and were surprised that we still saw elevated salt levels at these sites. We found elevated levels around Farmington Hills that we were surprised to see because we were way past winter salting season. We also found some hot spots in and around Washtenaw County. We're wondering if there's something else going on, as there could be salt contributions from groundwater because groundwater can have historic salt levels from less recent salt applications, or it could be the fact we have naturally occurring levels of salt where groundwater flows. And that is where we turned to (EGLE), and we are looking into this with them.”
Chris Bobryk, watershed manager for the Clinton River Watershed Council, said his organization has also participated in the Izaak Walton League’s winter salt study. Bobryk said that he and his citizen scientist volunteers also noticed that fluctuating levels of chloride correlate with stonefly populations. Other observations they have noticed include an influx of invasive non-native aquatic plant species such Eurasian watermilfoil which can tolerate saltier water.
Bobryk said that in addition to limiting the amount of salt on roads, sidewalks and parking lots, average citizens can work to abate this problem by helping to build a greener infrastructure by capturing stormwater runoff and holding it in place with rain barrels or rain gardens.
“When increasing chloride levels begin to impact the health of wildlife, that is a good indicator that human health will also be affected,” said Bobryk. “This is why studying the health of these rivers is so important. When we begin to lose species of invertebrates whose habitats are being crowded out by invasive species, that is going to negatively affect the quality of our drinking water. And what happens in the winter in terms of how we put down salt on our roads will eventually affect our bodies of water in summer that we count on for enjoyment and recreation. So we have to keep this issue in the forefront of our minds year round."
Ellen Foley, a researcher and associate professor at Grand Valley State University, is hoping that her efforts of studying one small lake in Kent County can serve as a wakeup call for safeguarding the rest of the state’s some 35,000 inland lakes and ponds. In Oakland County alone, there are 1,200 such bodies of freshwater, according to county officials.
In April 2022, Foley drew her last water sample from Church Lake, a 20-acre private kettle glacier lake in Grand Rapids that teems with fish, turtles and other aquatic life. But just below the surface, Foley said are "concerningly" high levels of chloride that have created a dead zone that chokes the lake of needed oxygen.
“Church Lake takes runoff water from a nearby highway, and I’ve taken some chloride levels in the winter as high as 1,000 milligrams per liter. In spring and summer samplings, we still saw lingering effects of chloride concentrations when the road had not been salted for months. Chloride gets stuck in the environment, and it is very difficult to remove. Though the numbers have fluctuated some, the high levels in the lake are consistent. The high levels of chloride lead to higher nutrients at the lake bottom via a process called internal phosphorus loading. This is an area that up until now has had little research but demands further examination if we are to understand how rock salt is affecting Michigan’s inland lakes.”
Foley said that local officials and others are paying attention to her research findings but are questioning if there is anything that can be done to sacrifice less safe winter driving for the sake of the health of the lake. She said that road salt is somewhat of an “out of sight, out of mind problem” in lakes. But she hopes that through her research on one lake in the state, people will become more aware or think about how salt put out on the roads may be impacting a body of water where they live or enjoy visiting.
“Church Lake’s chloride levels are an extreme version, and in general I do not think people are aware. But if you live on a lake and it is located near a road where salt is applied, chances are the runoff is causing problems there too.”
Another way of measuring salt levels in freshwater lakes is to monitor how well it conducts electricity. Just like certain metals, water can carry an electrical current. The higher the salt level, the more conductive the water, which may indicate that conditions for aquatic life that depend on salt-free water may be declining. A healthy lake system may have conductivity rates of zero to 200 micro Siemens per centimeter – a measure of electrical conductivity.
Jennifer L. Jermalowicz-Jones is the founder of Restorative Lakes Sciences, a 10-year-old consulting firm whose clients range from municipalities to private lake development associations who are looking to remediate the quality of their lakes through better sustainability and conservation practices outlined in laws such as Public Act 451 of 1994, the Michigan Natural Resources and Environmental Protection Act (NREPA), and under federal law from the U.S. Environmental Protection Agency under the federal Clean Water Act.
Jones said her company has been monitoring the conductivity of Wing Lake and Upper Long Lake in Bloomfield Township, and Lake Angelus, between Rochester and Auburn Hills, where conductivity levels have reached between 800-1000 micro Siemens per centimeter.
“We typically like to see conductivity between 200-500, which is ideal for an inland lake,” explained Jones. “We get concerned when we see conductivity numbers over 800. That's when levels have a negative impact on aquatic flora and fauna and once it reaches 1,000, levels are toxic."
To remediate these levels, Restorative Lakes Sciences takes several data sets at certain times of the year and graphs the changes over time to detect what events cause a spike in lake conductivity. Certain events and parameters – like a heavy rainstorm or an uptick in phosphorus – causes conductivity levels to rise. Once they present these numbers to lake association boards, together they look for the source of the problems. Faulty septic and storm drain systems are usually the biggest culprits.
Jones said that with this knowledge, the lake and homeowner associations around these lakes have worked to reduce the amount of salt they use on roads in their development, and look towards alternatives such as sand brining or even beet juice. Slowly, the salt levels in these lakes are coming down.
“Our clients have been mitigating the amount of road salt they have been using with alternatives to reduce runoff, and that has made a difference,” said Jones. “And they've been changing out some of the road salt with other remedies to decrease that runoff and that has made a difference. Even though using beet juice has its problems because of its sugar content, it has less of an impact than salt, but there is no magic bullet here. So, we're hoping over time with these numbers that were superficially high for a couple of years will start to trend downward.”
Large-scale deicing operations needed to keep Michigan’s 122,040 miles of the public road at optimal safety levels in the winter call for a lot of salt – nearly a half-million tons of the stuff.
Michigan’s Gregg Brunner, director of field services for MDOT, explained that MDOT has adopted the state’s best practices plan for minimizing the discharge of chloride and sulfate into surface waters.
One remedy that is continually expanding is a process known as brining. Rather than dispense dry rock salt onto a road, a slurry of sodium chloride mixed with water is created. It has a freezing point lower than pure water and, as such, is a useful tool in reducing the adhesion of snow and ice to road surfaces and it also stretches out salt supplies and saves money. MDOT uses pre-wetted salt and brines and applies these substances to roads ahead of a storm, depending on the weather conditions.
“MDOT is piloting three brine-only programs, one in partnership with Montcalm County, and the others are at MDOT-owned facilities in Mount Pleasant and Grand Ledge,” Brunner said. “Using salt brine exclusively has the potential to decrease salt usage by 40 percent based on data from other states.”
In other best management practices, MDOT deploys advanced GPS and weather monitoring systems onboard its vehicles to give its highly trained drivers the best real-time decision-making data to determine when and how much salt should be applied to the roads.
Brunner said, “The vehicles are regularly calibrated to not dispense too much salt and are equipped with wing plows that more efficiently push away snow and reduce the need for salting, among other deicing techniques. The adoption of snow plows to cover more area faster and potentially reduce the need for salting.”
The speed of a salting truck is also a crucial factor in proper salt application. MDOT in 2012, released results from its salt bounce and scatter study, demonstrating the correlation between a salt truck’s speed and wasted improperly distributed salt. Waste increased dramatically the faster the trucks traveled. Based on an annual $3.96 million budget on seasonal salt expenses, salt trucks going 45 mph wasted 45 percent, or $1,762,200, but trucks traveling at 25 mph lost nine percent, or $355,080 worth of salt. Brunner said this led to adjusting truck speeds whenever possible to keep more salt on the roads and less scattering into medians.
Brunner said MDOT adheres to EGLE’s salt storage guidelines and has improved storage facilities with regular repairs and necessary replacements.
“MDOT encourages our contract agencies to do the same and will only participate in the cost of their salt and brine storage if they are built to meet these requirements,” explained Brunner.
While there are alternatives to salt, Brunner said cost and limited availability of alternative deicing substances are the main reasons for sticking with salt to treat winter roads.
“Chloride plays a key role in lowering the freezing point of water which melts the snow and prevents the bonding of snow/ice to the pavement,” explained Brunner. “Once that bond is broken, snow and ice can be plowed from the pavement relatively easily. There are other chloride-based products that perform a similar function, such as calcium chloride and magnesium chloride, but they are more expensive. Agricultural by-products, such as beet juice, can also be added to chloride-based deicers. These byproducts contain sugars that can combine with the chlorides to help with lowering the freezing point of the active ingredient.”
Brunner said the only non-chloride deicer available – calcium magnesium acetate (CMA) – is used sparingly because it costs 40 times more per ton than salt and is not as effective at melting snow and ice.
With all this said, Brunner stressed that when it comes to road safety, nothing beats salt.
“The idea of ending the use of salt is not currently practical. Salt is by far the most abundant and least expensive effective option for de-icing and anti-icing roadways and bridges. MDOT supports using road salts in a way that best avoids negative environmental impacts and pursues ways to reduce its use.”
On a smaller, local scale, municipalities have also adopted deicing alternatives such as brining. Bloomfield Township Department of Public Works Superintendent Noah Mehalski said the township’s annual salt and salt equipment budget has averaged $200,000, and Mehalski said this is proof that the township has adapted best salt application practices even though the cost of salt has shot up since around 2008. He noted that Bloomfield Township was one of the first municipalities to voluntarily apply for an NDPES permit back in the 1990’s.
The township has 12 vehicles to deice the roads. When a truck is fully outfitted with the most advanced plowing deicing methods, Mehalski said a vehicle can cost upwards of $400,000. Bloomfield Township has been shipping in brine made in Farmington Hills for 15 years, stored in a 11,979-gallon tank, in addition to using rock salt kept in a domed concrete structure on the township’s main campus on Telegraph, which can store up to 3,500 tons. Keeping in compliance with NDPES, the facility is not located within 50 feet of a lakeshore, stream bank, or wetland, nor is it located in a 100-year floodplain.
Mehalski said none of the operations or safety measures of storing or deployment of salt or brine comes cheap, and the township did have some budget reductions in its snow operations in the last several years.
"But diluting salt through pre-wetting or brining makes most economic sense for municipalities staring down harsh Michigan winters,” he said. “Outfitting a truck to disseminate brine is more expensive than conventional salting trucks, but I am grateful that the township board recognized and made the approvals to purchase this equipment. It is certainly more cost-effective to put salt down in a solution. Even before the environmental factor came up, the expense was really the big push that sent municipalities looking to how they can save money on treating the roads in the winter. “
Lauren Wood, director of public services for the city of Birmingham, said in the last 20 years, the city has taken proactive steps looking for alternatives to rock salt, including at one point using a mixture of beet juice and brine and pre-wetting rock salt. Seven years ago, the city began to make its own brine, which is spread on the roads ahead of a snow or icing event for more efficient snow and ice removal. Wood said in the event of a large snowfall, snow is removed from streets and is trucked to designated sites as approved by their NDPES permit, including the parking lot at the Ice Arena on Lincoln Street. They never dump snow into Rouge River tributaries, she said, as not only do they not have access to it, but it does not comply with their NDEPS permit.
Wood said that with fluctuating salt prices and a high variability in snowfall each year, it is hard to gauge just how much money the city saves in the long term by brining as opposed to just relying on rock salt. But over the years, Wood said overall, the city has had to order less salt since it began creating brine and they have decreased its salt usage by 35 percent.
“In addition to being more environmentally friendly, pretreating the streets ahead of a major winter event with a brining solution is the most economic and environmentally viable solution. Pretreating the roads with brine minimizes the amount of rock salt needed to go on the roads on a second sweep.”
Much of the strides that EGLE is beginning to take in terms of mitigating levels of chloride in the state’s freshwaters come from looking to other Great Lakes states such as Minnesota and Wisconsin. Through public education and best practice implementation strategies, the two states have demonstrated that they are successfully reducing the amount of salt spread on their roadways.
In its 2020-2021 Annual Winter Maintenance Report, the Wisconsin Department of Transportation reported that its use of salt dropped to its lowest level in 30 years thanks to advanced deicing techniques. The report said that the state used disproportionately more salt during more severe winters. Because of a mild winter last season, coupled with better salting practices, salt use in Wisconsin decreased 23.8 percent from the previous year, at 324,265 tons. In comparison, Michigan uses on average about 450,000 tons of salt each winter. If MDOT migrates to a 23 percent brine solution instead of rock salt, it can reduce the amount of salt going onto the roads by 40 percent, claims the agency.
In its 2021 Sulfate and Chloride Water Values Implementation Plan report, EGLE stated that much of the problems with increased chloride levels in freshwater are due to public demands to more widely and frequently salt roads in the name of public safety.
As a response, EGLE officials state in the report that they have taken cues from Minnesota to educate the public on when salting is effective, and when people need to accept it is ineffective. The Minnesota Department of Transportation was able to adjust its practice of maintaining bare pavement during a storm to maintaining bare lanes after surveying the public. In turn, MDOT developed a public education outreach campaign using the phrase “More salt...not always the cure for slippery road.” The goal is to educate the public that normal winter conditions are considered between 20-30 degrees. When temperatures decrease below 20 degrees, salt becomes less effective, so no matter how much is applied as the pavement will still quickly refreeze.
Some municipalities have communicated their adjusted salt application approaches with residents through social media and email distribution lists. A municipality may communicate a focused strategy of salting intersections and hills as a priority versus ineffectively salting.
Wisconsin Salt Wise, a nonprofit coalition of organizations from across the Badger State created and staffed by one alumni and a half-dozen student volunteers from the University of Wisconsin that trains the state’s municipality professionals on best practice salt management techniques, offers the most pragmatic instructions to the private home or property owner visiting its website. For example, all that is needed to deice a 20-foot-long driveway or 10 average-sized sidewalk squares is one 12-ounce coffee cup's worth of rock salt.
Allison Madison, a science and sustainability educator by training, is the sustainability and development coordinator for Wisconsin Salt Wise. Madison explained that public health officials in Dane County, Wisconsin, since the 1960s have been aware of the adverse effects of salt pollution through monitoring changes and chloride concentrations on the Yahara Chain of Lakes.
“Softening water, coupled with deicing winter roads with rock salt, led to a widespread problem of increased chloride that could not be extracted from the wastewater stream that flows into Madison’s wastewater treatment plant, which serves up to 14 municipalities throughout the county,” said Madison. “For guidance, Wisconsin looked across the border to environmental authorities in Minnesota, which developed a training program for municipalities on how to properly manage winter salt applications to minimize impacts to waterways. Since 2018, Salt Wise has rolled out its own training workshop, emphasizing proper equipment calibration, using brine instead of pure rock salt, and educating municipalities on how they can restrict winter salting by limiting the practice on residential streets and saving heavier applications for main arteries and highways."
Above all, Madison said a cultural shift is needed in the winter. Unless it is for emergency purposes, the expectation that every road and surface should be cleared of snow to the pavement is not a sustainable solution. It's a practice Michigan can certainly, and easily, adopt.