How Salt on the Road Impacts Our Waterways

why our relationship with road salt is due for an overhaul
impact road salt waterways
© Can Stock Photo Inc. / Borodin

Every fall, we collectively brace ourselves for the weather ahead. For many regions, freezing rain, massive dumps of snow, and slippery roadways all come with the territory. Road salt (sodium chloride) has long been touted as the best line of defence and is used liberally by maintenance crews and municipalities to keep roadways and parking lots clear and ice-free.

While road salt is very effective, there are far too many examples of road salt application being overdone. Many of us can relate to walking through a parking lot only to find piles of salt that have accumulated. Salt-stained shoes, damaged car undercarriages, and sore puppy paws are common occurrences. And while these may seem like inconvenient but necessary impacts, road salt is wreaking even more havoc on nearby streams, rivers, and lakes, as well as groundwater aquifers deep underground.

It doesn’t need to be this way.

The Salt of the Earth

As excess salt is finding its way into freshwater habitats, it’s causing significant damage to the species that live there.1 Freshwater species like mussels, salamanders, frogs, and other amphibians are particularly vulnerable to salty water and for many of these creatures who are already facing challenges like habitat loss, the added stress of salt is causing real problems.  

In the Greater Toronto Area, for example, waterways near urban centres have seen shocking spikes in sodium chloride concentrations that linger long into the summer months. Water quality monitoring data shows that salt levels are above the threshold that freshwater species can tolerate for most of the winter and early spring.2 And in some instances, spikes in sodium chloride can reach saltiness levels found in the ocean! Salt can be so prevalent in urban creeks and streams that saltwater creatures, such as the saltwater-loving blue crabs found in Toronto’s Mimico Creek a few years ago, can survive much longer than nature would have otherwise allowed.

Excess salt isn’t only impacting the plants and animals who call these waterways home - it’s also finding its way into groundwater aquifers used for drinking water in parts of the Great Lakes region. One city in the area has had to issue public warnings for those citizens on low sodium diets to be wary of the amount of salt that may be getting into the drinking water supply!3 Even our infrastructure is negatively affected by the salt. Across North America, expensive bridges are ageing much more quickly than they were designed to, and road salt is the main culprit.

Saline Solution

The root caue for many of these problems is over-application and experts estimate that road salt is applied in quantities 30 to 100 times more than necessary.4

To melt one sidewalk slab of pavement, only a small handful (about 3 ½ Tbsp, or the size of a film canister) is needed. And yet, it is so heavily overused that it’s quite common to crunch through it as you walk or see piles of it accumulated on roadsides and sidewalks. Of course, those applying salt don’t do this to intentionally harm the environment. The fear of injuries and liability drives many companies to apply the salt in excess. However, all that extra salt doesn’t make us any safer.

We need far less salt than we think in order to melt ice and snow. And, salt only works at a precise temperature. From 0°C to about -10°C, salt works really well. When the temperature is colder than -10°C, however, its effectiveness starts to dwindle. For places with especially cold winters that see many days drop below -10°C, alternatives (or “salt-ernatives”!) are commonplace. Many cities have found that using brine as a pretreatment on pavement before rain or a snowstorm can help prevent ice from forming in the first place! The city of Calgary, for example, has been using beet juice brines and other alternatives for several winters now with great success,5 while a city in Wisconsin uses cheese brine to pre-treat its roads.6 (Go Cheeseheads!)

A Grain of Salt

You may be thinking: beets may be great for roads, but what alternatives can I use on my own property to keep walkways and driveways ice-free? The best approach is to shovel really well before applying salt and only shovel and salt the areas you need to get around safely. It’s important to remember that less is more (about a handfuls-worth per sidewalk slab).

Shake it Up!

While homeowners can make small changes to limit their personal use of salt in winter, government action is required to regulate how road salt gets applied in large quantities. Landscaping companies and private property owners need support in the proper application of road salt to ensure that health and safety and environmental safety are both achieved. Luckily, there are more and more programs for those applying salt to learn techniques to reduce how much is applied. The Smart About Salt program, for example, is a way for a company to get a certification in proper salt application.

The good news is that excess road salt and salty freshwater lakes and rivers are starting to get the government’s attention. In the U.S., New Hampshire has been leading the way by introducing legislation that promotes certification programs for proper applications and liability relief for certified applicators. Illinois, Colorado, and Minnesota have followed suit and begun efforts to help ensure road salt is being applied appropriately. Ultimately, the government needs to set objectives for sodium chloride to better track and monitor its impacts and the areas where it causes the most negative effect.

Another way everyday people can take action is by pointing out excessive salting when we see it. For example, if you notice that your local grocery store consistently puts way too much salt on its parking lot, it could be very effective if you mention it to management—it might even save them money!

The implications of too much salt in our freshwater isn’t widely known or understood, and education is key: both for personal users and businesses. If companies, governments, and individuals all take the right steps, we can make our waterways less salty and healthier for the people and species that call them home. To follow along with the road salt reduction pursuit, check out #LessSalty on Twitter.

You may also enjoy: Road Salt and the Environment: The Gummy Bear Experiment

For references visit ecoparent.ca/extras/win20.

Sign up for our e-newsletter!