The Decibel - Why road salt causes Canada billions in damage each year

Episode Date: February 2, 2026

Snow and ice is a fact of life in a long, Canadian winter. So are the millions of tonnes of salt that is used to combat it on roads across the country. But there is a cost to all that salt: damage to property, waterways and other parts of the environment and infrastructure – totalling billions of dollars annually.Patrick White, reporter for The Globe, explains the science behind why Canada is the biggest consumer of road salt in the world and why the same chemical that is necessary for a winter climate is also endangering water systems.Questions? Comments? Ideas? Email us at [e-mail] Hosted by Simplecast, an AdsWizz company. See pcm.adswizz.com for information about our collection and use of personal data for advertising.

With a Canadian winter, you can be sure of a few things. Wind chill, snow, and road salt. Those chunky crystals that you crunch over as you walk on a sidewalk or drive down a street are the go-to de-icing technique for many parts of the country. And with good reason. One study found that road salt reduced collisions on icy roads by 90%. But there's just one problem. That salt doesn't just burn through ice.

It accumulates in our soil, our waterways, and corrods our infrastructure, to say nothing of your boots. So what's a cold country like Canada to do about it? Patrick White is a staff reporter at the Globe who covers water issues. He looked into the impacts of Canada's road salt use and whether the alternatives out there are any better. I'm Cheryl Sutherland, and this is the Decibel from the Globe and Mail. Hi, Patrick. Thanks so much for coming on the show. Hey, thanks for having me. So Patrick, I want to start off by understanding exactly how much salt Canada uses in the winter.

Do we even keep track of that number? Kind of. Okay. The federal government keeps track of kind of government use. So they get information from most of the municipalities about how much salt they're using on the roads. The yearly average is 5 to 7 million tons of salt on public roads every year. So that is a lot, but their estimates say that it could be almost twice that. It could be, you know, 10 to 14 million tons because there's so much salt that is used on private property,

your mall parking lots and that kind of thing that just doesn't go into those federal numbers whatsoever. So 7 million tons, I did a little math before this, that's the equivalent weight of 60 CN towers. What? So across the country, that's a lot of salt. Okay. So that's a lot. Can we put that into context? Are there any comparisons we can make with other icy countries? Yeah. I mean, a lot of countries use a lot of salt countries in Scandinavia. The U.S. is probably for total salt use. It probably leads the world. There was a Norwegian study a couple years ago that looked at Norway, some of the Scandinavian countries, the U.S., Canada, I mean, the chief salt users, the chief offenders for salt use in the world.

So the U.S. has way more roads than us. So they're going to use more. But on a per kilometer basis, Canada is top of the world for road salt use. We're number one. We are number one. I'm not sure we want to be there. Yeah, that's really interesting. So are we just using more than other countries because we get more ice or what's happening?

Because most of our major cities are located right around the 49th parallel, Well, the winter, average winter temperature tends to be around like zero to minus 10 right in there. That also happens to be the perfect band for road salt. Those are the temperatures where road salt is at its most effective. So normal road salt, which is just normal sodium chloride, a version of the stuff we use on our tables, it works best at temperatures above minus 10. So as soon as it's minus 11, minus 12, normal road salt. normal road salt doesn't really work that well. So when you think about where most people live in Canada, Toronto, Montreal, Calgary, across the country,

road salt is going to work really well in those particular cities and therefore we use a ton of it. Okay. So that makes me think that not everywhere in Canada has those temperatures, right? So there must be places in Canada that do not use road salt. Yeah. So we see in cities where it's a little colder than that ideal road salt operating temperature, They tend not to use quite as much salt. We're talking the Winnipeg's, the Edmontons, where it's quite a bit colder.

They will use a mix of things all winter long. I know I lived in Winnipeg for a little while, and there was a lot of dirt, gravel, sand that spread on the roads. Didn't tend to be as much salt there, though, again, when it was in the right temperature, salt would go down and they'd use it. Below minus 10, you stop thinking so much about getting rid of the snow and ice and just creating traction, creating friction with your tires. So they will spread down a lot of dirt and gravel. Those come with other problems, but they don't have the same kind of pervasive environmental and infrastructure problems that salt can create. Right, right. And we'll get into that. Okay, so let's talk about why salt works at this specific temperature. So when a truck lays salt across an icy road,

why is it so good at melting ice? When you lay salt down, it basically lowers the freezing point of water. So normally, of course, in the metric system, we all know it's very convenient. Water freezes at zero degrees. When you mix salt with that water, that will actually lower the freezing point quite substantially for water. So you can get water mixed with salt. You get it down to minus 10. It's still not going to freeze into ice. So it really prevents ice from forming on the roads. And as I found in some research, when you can spread salt on the roads and prevent ice from forming, you reduce the amount of car accidents by around 90%. They almost eliminate them.

Wow. That's a big number. It's a big number. For public safety, we need salt. Okay, yeah. And so the idea here is that municipalities will put down salt, I guess, maybe ahead of a winter storm, or are they doing both? They're doing salt before and after, say, ice has developed on the roads.

Yeah, they need to do both, but the most important thing is to do it ahead of big storms. Oh, great. He's had to big freeze-ups. And actually, some of the people who study this I talked to said one of the most important things that municipalities can do is get accurate weather forecasting. Because if you can get that salt down, and especially if you can use salt brines, which a mixture of water and salt and put that onto the road, it kind of binds to the pavement. And it'll prevent the ice from binding to the road whatsoever. So if you put salt on top of it. pop of ice and snow, it'll take a while to work and there'll be some dangerous conditions.

But if you can salt that road before those inclement conditions start, then you can kind of eliminate the chance of ice forming whatsoever. Okay. Let's talk about what happens after we apply salt to the roads, because this is where kind of the issue comes in, right? Where does the salt go from there? It goes everywhere. So if you look at my Toyota, you know, that the salt goes all up in my Toyota and makes it all rusty.

my bike is rusty. So it goes into personal vehicles. It goes into our infrastructure, our bridges, anything metal that will corrode it. And one of the things that I've found in looking at this that's kind of underappreciated is really how much it's getting into the environment. That salt just washes off the road and goes directly into our environment. And it soaks into streams, rivers, lakes. And it is causing huge problems for aquatic life around major roads. roadways.

Okay. Let's talk about the lakes then. What happens when lakes get too salty? There's a couple things, but one of the least appreciated is what it does to zooplankton. Zoo plankton are a really important part of the food chain. They eat the algae that's in the water and then in turn little fish eat the zooplankton. So if you're going to have fish or larger organisms in a body of water, you need the zooplankton there.

Yeah, knock on effects there. Exactly. You take that link out of the food chain. and really the whole thing collapses. But they don't do well over chloride levels of about 120 milligrams a liter. And that some researchers, one researcher I talked to has actually found that they don't do well over even five milligrams a liter of chloride. But the Canadian Council administers the environment have set this level of 120 milligrams

per liter. Anything above that is going to be dangerous for aquatic life. We have some real-time stats. that we can look at for the Toronto area. There are water bodies right around major roadways in the greater Toronto area that are over 3,000 milligrams per liter. So that's not only going to affect zooplankton. That's immediately lethal to zooplankton. And a lot of other life, too, just simply can't survive in anything like that.

There was a study in Ottawa I looked at that found one waterway there was over 15,000 milligrams per liter, which is much... 15,000. One of them was even higher than six. seawater. So there's normal aquatic life just simply can't survive there. And that causes everything to crash. Yeah. I mean, and there's also a lot of roadways. I'm going to speak for Toronto specifically since I live here. But I mean, we have the lakeshore, which is, you know, the name says it. Lakeshore. It's right near the water. Yeah. Yeah. So that goes right along Lake Ontario. All that salt essentially will end up in Lake Ontario eventually. Luckily, we're blessed with these

these great lakes, we can sully them a lot as we found out over the last couple of centuries and they are incredibly resilient because they are so deep and so big. But they, along the shorelines, there have been studies that show that chloride levels are simply getting too high. One of the other things that salt can do in these water bodies is for lakes to be viable places for a lot of organisms, they have to undergo this kind of seasonal shifting of different layers in the lake. So the nutrient-heavy bottom layer will come to the surface in the spring and it will provide all kinds of nutrients for all the organisms that live higher up in the lake. High salt levels prevent that from happening.

Or they make it so that shift in the kind of thermal cline of the late happens later or not at all. When that doesn't happen, again, organisms simply can't thrive in those water bodies. We'll be right back. Let's talk about our drinking water because I understand that that's also being a affected. So tell me how road salt effects are potable water or our water treatment facilities. Yeah, well, most water treatment facilities cannot take salt out of the water. That's a really expensive process called desalinization. And a lot of countries that are not as water rich as we are

have gone to desalinization. It's really expensive. And you end up with this really salt intense brine that you then have to dispose somewhere. So it creates all of this waste. In a lot of municipalities in the country, they rely on groundwater. And I talked to some people in Waterloo where this is the case. Waterloo relies entirely on groundwater. PEI is another place that relies entirely on groundwater for its tap water. And the chloride from road salt does eventually find its way into the groundwater.

And unlike the lakes where it'll dissipate and move on, it sits in that groundwater and can end being pumped up into your tap water. And mostly groundwater is not as treated as much as surface water. So there's no way of getting that salt out of the groundwater supplies. And in Waterloo, they're having a real problem with it. A number of wells have now become too salty. And they, as a result, have a salt reduction program going on with their road salt crews where they're really trying to reduce the number of road salt to prevent this from happening. This has also happened at in a few places in the states where the water's just been getting so salty that people start reporting that their coffee makers are rusting out and things like that. So it has a lot of effects.

I mean, I imagine it must change the taste of drinking water. But is it harmful for people to drink salty water? I don't think in these low levels that it's directly going to harm your health, but it is going to have a lot of impact on infrastructure. So we have around 20% of the pipes in Canada. Canada cast iron. There's a lot of other steel pipes. And salt in the water causes bad corrosion. So a lot of these pipes we're expecting to last us 50 to 100 years. If we have really salty water, that's not going to be the case anymore.

We actually just heard about major ruptures happening in parts of Canada. Like there was one in Calgary, right? Is that because of what was going on with the salt? Yeah. So they've had two really bad ones in Calgary in the last 18 months. There was one in the summer of 2024 along the Bears Pass South Feeder Main. that supplies more than half the water for all of Calgary. They had a major rupture caused weeks and months of major restrictions, water restrictions

in Calgary. And they did forensic investigation afterwards and found that there are a number of possible reasons. But one thing they pointed to is they found that really high chloride levels in the soil around that rupture. And the investigators posited that those heavily chloride soils from road salt likely led to that or at least accelerated the corrosion that resulted in that rupture. They had another one right at the end of last year, right at the end of 2025.

And again, it's likely we're going to find out that there are heavy chloride levels in the soil around leading to corrosion along that line. So that's going to cost Calgary immediately the previous rupture cost them around $50 million. They're going to have to replace that whole line. It's probably going to end up costing that water system. somewhere in the realm of a billion dollars. And then if you look across Canada, this kind of thing happening with corrosion from road salt, it's much higher than that.

Okay, so road salt is sleeping into our water. But what about when it's not near water? Is it a problem if it builds up in the soil? One thing I did hear was from landscapers who during the summer, they have this job of beautifying our private and public spaces and putting in shrubs and making sure the grass is nice and green. And during the winter, those same people often switched to the job of snow and ice removal. So they're the ones putting down all the salt that then is seeping into the soil and getting on those lawns and getting on those shrubs and just kind of almost has the effect of burning them. They're actually killing off that lawn and shrubs.

And it has a similar effect on agricultural fields. You can see along the edge of highways where things have a hard time growing where it's getting really, really salty. One thing I haven't talked to you about yet are the roads themselves, right? What effect does a lot of salt have on the road conditions? Yeah, well, salt is incredibly corrosive. So there's really three types of road salts that are used. The most common is sodium chloride. Then there's magnesium chloride and calcium chloride.

And I've actually heard from people who work on road crews that sodium chloride is bad for roads, but mainly for any kind of metal infrastructure. So your bridges, your elevated roadways like here in Toronto, there's the Gardner Expressway. But the worst is the magnesium and calcium chloride, that they actually accelerate the corrosion even more. I mean, any time I've looked up at the Gardner Expressway when I'm driving into work, for instance, here in Toronto, you will often see places where they've taken away pieces of concrete or crews or the concrete is fallen away. and it'll expose the rebar inside the Gardner Expressway, and it's rusty. It's all corroded. They're currently undertaking like a billion-dollar renewal project on the Gardner Expressway.

A big reason they've had to do that is the corrosion of that rebar. The chloride ions will go seep right through the concrete and kind of attack the steel rebar inside. So as soon as that steel rebar goes, then the structural integrity of the, Gardner of the Champlain Bridge in Montreal of many other pieces of infrastructure just a roads away. So in the example of the Champlain Bridge, I think it was only there for about 50 years before they decided they needed a replacement. A lot of the reason was the corrosion caused by road salt.

And there was also that story of the mall parking lot in Elliott Lake, Ontario, right, where it collapsed and killed two people in 2012. Yeah, that was a horrible story. It was the parking garage on the side of that mall. I was there once before the collapse. And it had huge water problems. They were always dealing with horrible water leakage problems in that parking garage. But at the same time, they were salting it constantly.

Elliot Lake is a cold place. So all that leakage was bringing with its salt that just leached into the structure of that parking garage and eventually caused it to collapse. And it was a really tragic story there. Yeah. Yeah. So this could have really bad effects. You know, in the case of Elliott Lake, people have lost their lives. But it's also very expensive, right?

Is there any way to know how much it's costing us as taxpayers to keep repairing the roads that are being corroded by salt? Yeah. A few different organizations have tried to estimate how much salt is costing us. Basically, how much we're paying to renew the infrastructure for every kilometer of salt we used. and I think it was the eco-fiscal commission in Canada. It's a non-governmental organization. Estimated the annual costs are about $5 billion we're spending to rehabilitate or replace infrastructure

simply because it was corroded by road salt. So $5 billion, that's a significant amount of money every year. And again, it's a pretty rough estimate, so it could be much higher. So if salt is damaging to our water, vegetation, and infrastructure to say nothing about our shoes and the feats of dogs. Why do we keep using it? It works. Simple as that.

It's simple as that. There's also this liability issue. And it's one thing that was suggested to me could be done to reduce salt use a lot. Private companies that use salt that spread them on near parking lots and everywhere else. There's extreme excessive salt use on all of them. And one reason that companies told me they were doing that is because they're worried about slip and fall lawsuits. So in Ontario and a few other provinces, if somebody slips and falls and hurts themselves, if they do sue for the accident, it's not necessarily the owner of that property that holds all of the liability and the responsibility. It can be the private contractor that put down the salt that can hold 100% of the liability in this province.

And if it can be proven in a lawsuit that the company didn't put down enough salt, and that is kind of subjective, then they can win that lawsuit. So private contractors say that they're over-sulting. Yes, they are oversalting. They admit it. And the reason is because they don't want to go below that threshold that might be provable in court that they didn't put enough in. They don't want to be called negligent. So they're putting as much salt as they possibly can on these places to avoid that. A lot of these are small companies.

And just being named in a lawsuit, they told me, could be like $20,000 or $30,000, not something they can afford. So they've suggested in Landscape Ontario, one of their bodies that represents a lot of these companies, has said, if Ontario could introduce law or legislation that said that these contractors didn't have to hold all of the liability for this, then they could start salting less. And that, again, would do some of the burden that these private properties are putting on their parking lots and their sidewalks and everything else. Everybody I interviewed for this story, I kind of asked, you know, what can we do about this? What can it's so corrosive. It's so expensive. As we've mentioned, it's fatal in some cases.

What can we do to replace this? And it's really uncertain what we can do to replace this. There have been a lot of alternatives that have been used in different municipalities. these, there's pickle juice, there's beet juice, there's all kinds of kind of salty brines that have been used. It's like there's a whole delicatessen worth of stuff they've laid down on the road. It works pretty well, and sometimes it works even better than salt, but it's also quite expensive. Salt. Good old sodium chloride is really cheap. I mean, maybe a solution. I don't know. Tell me about this, but could we not use less salt? We could. We could. So there was one,

PhD student at Toronto Metropolitan University, I talked to who's really devoted the last few years of his life to studying the salt issue. He said that a lot of the alternatives not only like beet juice are not only more expensive, but some studies have found that they're even more lethal to aquatic life than normal salt. And he said, well, it would be possible for governments to start public education campaigns and say, when we have lots of snow, really cold, lots of ice, just slow down. Stop expecting that you're going to be able to drive at 120 kilometers an hour. Stop expecting that you're going to be able to go for your morning run. The sidewalks are going to be completely clear of all ice. Wear winter boots. Always wear winter tires.

Maybe that could actually be regulated. I know it is in Quebec. If you did a kind of combination of minor regulation and public education and lower expectations for Canadians, perhaps we wouldn't need to spread as much salt as possible, but really, he said reduction is the only way through this. Until maybe 70 to 100 years out when climate change will intervene and we may not have winter anymore. Yes. But I mean, what I'm hearing here is that, yeah, we have to kind of embrace winter and slow down.

Yeah. If it's snowy, if there's ice, if it's lower than minus five, just expect that you're not going to be able to make that 30 minute commute in 35 minutes. Maybe it's going to take an hour. Maybe you shouldn't be making it at all. Maybe with new technologies that we have that we kind of perfected over the pandemic, like Zoom, we just shouldn't expect to make it into work on snow days. If there wasn't this kind of expectation our roadways would be so clear during bad weather,

then maybe we wouldn't have to use so much. Patrick, this has been really interesting. Thank you so much for coming on the show. Yeah, thanks for having me. That was Patrick White, a staff reporter at the globe who covers water issues. That's it for today. I'm Cheryl Sutherland. Our producers are Madeline White, Michal Stein, and Rachel Levy McLaughlin. Our editor is David Crosby.

Adrian Chung is our senior producer, and Angela Pichenza is our executive editor. Thanks so much for listening.