Road salt a threat to freshwater lakes, study suggests

A new study suggests the use of road salt is posing a rising threat to freshwater lakes in parts of North America, including Ontario.

The research, published in the Proceedings of the National Academy of Sciences, predicts thousands of lakes will contain too much salt to sustain their current levels of aquatic life if current road salt trends continue over the next 50 years.

Researchers studied 371 North American lakes, including nine in Ontario, to gauge changes in chloride levels over several years.

The study found lakes near roadways covered in salt during inclement weather recorded significantly higher chloride concentrations, bringing them closer to the U.S. Environmental Protection Agency's legal pollution standard for chloride in freshwater.

Lakes in more remote areas did not record the same chloride increases.

In Ontario, for instance, Lake Simcoe's chloride levels have climbed five-fold in the past 10 to 20 years, while those in the less urbanized northwest region of the province have stayed relatively stable and well below the EPA's threshold of 230 millilitres of chloride per litre of water.