Salt, Safety and the Environment

If you're under 75 years old, there's never been a time when salt hasn't been used to remove snow and ice from the roadways you've driven on in winter. For most of that time, you've been aware of the trade-off — humans have been protected against collisions, but sensitive roadside vegetation has been damaged and animals have stopped living on roadway rights-of-way, in part perhaps, due to salt.

Over the past half-century, road maintenance departments have placed a high priority on keeping winter roads safe and passable. They have learned how to minimize the amount of salt they use to do it — saving money and reducing (but not eliminating) the environmental impacts. Vehicle owners, too, take measures by rust-proofing their vehicles against the effects of the salt used to de-ice slippery roads.

On August 12, after five years of study, Environment Canada announced its recommendation that road salts be declared "toxic" to plants and animals. The report is available online. The public has until October 11 to tell Environment Canada what it thinks.

For safety advocates, this is not an easy call. Canadians want to protect the environment and keep the roads safe and passable.

Labeling road salts as "toxic" could discourage their use to ensure safe driving conditions. By jeopardizing public safety, such action at the federal level would increase municipal and provincial liability.

If road salts are toxic, should they be replaced with alternative de-icing substances? Salt costs $50-$65/tonne, the alternatives $600-$2,000/tonne. Given the current focus on reducing taxes, it seems unrealistically expensive to replace road salts at this time.

The report seems to apply the same standard to both the natural environment and the engineered roadway drainage system. Bridges and roadway rights of ways are engineered with drainage ditches and runoff impoundments to manage the high-chloride runoff and prevent environmental contamination while providing public safety. Yet the report says these ditches and impoundments should not only be protected against chlorides, but should serve as replacement "habitat" in urban areas.

Salt-tolerant species of plants now thrive along the roadways where more salt-sensitive native species once grew. The report identifies this displacement as a problem. However, the native vegetation was destroyed when the roadway itself was built. Landscaping plans for Canadian highways select salt-tolerant species specifically so they can co-exist in the harsher roadway environment.

Public works departments are well aware of the adverse environmental effects of de-icing. Once a problem is identified, the highway design is often re-engineered or winter maintenance practices changed to correct it. The Transportation Association of Canada, whose members include road maintenance agencies, has a 275-page Salt Management Guide, Primer and Codes of Practice to address key issues relating to road salting.

In requesting the assessment, the Expert Advisory Panel recognized the need for de-icing agents to keep roadways open and safe during the winter, and to minimize traffic crashes, injuries and mortality under icy and snowy conditions. It stressed that measures developed as a result of the assessment must never compromise human safety.

Safety and environment do not need to be trade-offs. We can (and should) insist on both.

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