March 3, 2024

Winter road salting has year-round consequences

There are also some environmental concerns, as road salt ultimately makes its way into our soils, local lakes, and rivers. Salty water flows into our soils and local water bodies through surface runoff and stormwater pipes and eventually makes its way into groundwater. This furthers the long-term storage of salt in the environment and further impacts freshwater aquatic life, government infrastructure, and drinking water.

These concerns are usually voiced during the winter when we actively see salt trucks and piles of salt on our drives or walks to work for and school. While some of our worries disappear as the warm spring weather comes, my research shows the effects of extensive road salting on the environment last year round.

Road salt from streets is seeping into the groundwater and destroying our freshwater ecosystems.

No longer a winter-only issue

My research with Donald Jackson at the University of Toronto showed elevated chloride concentrations- which are highly correlated with road salt- which can now be found throughout the year in freshwater systems in the Greater Toronto Area. The impacts of road salt are not commonly studied in the summertime. However, understanding how it may be impacting the environment in the salt “low season” is important for understanding the gravity of the situation.

Research shows that the chloride concentration across rivers in the Greater Toronto Area exceeds the sustainable levels established in the Canadian Water Quality Guidelines for the Protection of Aquatic Life. (Lauren Lawson/FACETS), Author provided

Our study found that during the summertime, which is also the low season for chloride, chloride concentrations exceeded established Canadian federal guidelines for the protection of aquatic life.

At some of the sites monitored, we found that over 50 percent of the aquatic biological communities can be considered to be stressed by chloride based on these guidelines, which were based on toxicity tests of marine organisms.

This means that summertime is now a time of likely chloride stress, higher water temperatures, and early life stages of aquatic organisms (like eggs and larvae), which may be more sensitive to stress. These factors combined put marine species at elevated risk.

Why should we be concerned?

Road salt poses a risk for freshwater aquatic species, which rely on low salt levels. Freshwater species have specific biological adaptations to low salt levels, unlike their ocean counterparts, which have different types of adaptations.

Studies show that increased chloride concentrations associated with salt can lead to disruptions in food webs, as sensitive species are stressed at high concentrations. For an aquatic organism, salt stress can lead to the diversion of energy to maintain basic functioning, which means less energy is directed to growth and reproduction.

High road salt concentration in freshwater ecosystems can stress the aquatic life within it and disrupt the food web. (Shutterstock)

High salt concentrations have been found to lead to decreases in egg mass and growth rate for aquatic organisms. This essentially means sensitive species may eventually be “filtered out” of food webs, leading to declines in biodiversity.

Road salting leads to high concentrations of chloride and sodium in local waters. Increased chloride in drinking water supplies can lead to more rapid corrosion of drinking water infrastructure, such as private and municipal wells and pipes. This decreases the safety of drinking water. Increasing sodium concentrations is also concerning for those with hypertension.

To top it off, salting can lead to faster rates of corrosion of bridges and roads, putting road infrastructure at risk as well.

Lacking: efforts to reduce road salting

De-icing salts were first used in the 1940s in North America, and as their use exponentially increased with urbanization and road expansion, sodium chloride became the most popular. With an increased understanding of risks to the environment and human health over time, efforts to reduce road salt use include using alternatives such as beet juice.

Alternatives to road salt, like beet juice, could help reduce the salt in our streams, but they come with their environmental concerns.

However, these alternatives can be expensive and can come with their pitfalls, like the introduction of more nutrients into aquatic systems. Understanding how much salt needs to be applied and when is a crucial part of salt and ice management. Additionally, shifts in perspective of ice safety can be made. In some regions, for example, snow tires are required for vehicles, while people use chains, boot spikes, and other personal traction devices.

At a recent salt summit held by the Lake George Association in New York, a speaker adequately described our current relationship with salt as “oversalting comes from a place of love, concern and want of safety,” because icy conditions are considered unsafe.

However, short-term prospects of ice safety blind us to the love, concern, and want for the long-term safety of our drinking water supplies and environmental integrity.

Mitigating our winter road salt addiction

We need first to recognize the year-round impacts our winter choices can have and then take action to reduce the impacts. We can share the effects of road salt and the individual actions we can take, such as understanding how much salt needs to be put down on our private properties, adjusting our expectations of winter roads, and using snow tires and boot spikes to provide an added layer of safety.

It is crucial to understand how much salt needs to be put down on our private properties to safely get rid of slippery ice without oversalting. (Shutterstock)

On a larger scale, mandatory certifications for salt application can provide training for snow removal companies and have substantial incentives if designed properly. For example, the New Hampshire Green SnowPro Certification provides limited liability relief for snow removal contractors if they are certified.

This ensures snow management companies are protected, and their training programs are recognized as safe. Other organizations, like the Smart About Salt Council, provide the opportunity for certifications, training and general knowledge on salting.

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