Road salt a threat to freshwater lakes, study suggests

Road salt a threat to freshwater lakes: study

TORONTO — 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.

That threshold, according to lead researcher Hilary Dugan of the University of Wisconsin, illustrates exactly how destructive excessive chloride levels can be for freshwater ecosystems.

“It’s about one teaspoon in a five-gallon bucket,” Dugan said in a telephone interview. “We’re talking about pretty low concentrations. So when you think about the amount of salt that you see lying around on the sidewalk, it doesn’t take a lot to push these lakes to concentrations where we’re going to start seeing ecological changes. And we’re also going to start tasting the salt if it’s our drinking water.”

Dugan said researchers found that the lakes in their sample were at greater risk of elevated chloride concentrations if they had more than one per cent of the surrounding area covered by an impervious surface such as concrete.

Dugan said that surface would prevent road salt from being absorbed into the surrounding soil, leading to immediate run-off into a nearby body of water

Dugan said the presence of a single road within 500 metres of a lake was a strong predictor of elevated chloride levels in that body of water.

She attributes many of the chloride spikes to road salt, a substance the study suggests has made its presence felt in North American waterways in recent decades.

The report said 18 million metric tons of road salt were being sold in the United States by the end of the 1990’s.

Canada listed road salt as a toxic substance in 1999, yet the study said 5 million metric tons of it were applied to national roadways between 1995 and 2001.

Dugan said research on Canadian lakes was limited, saying lakes in Quebec and the Maritimes could not be included in the study due to lack of data.

Researchers did make use of figures available from the Experimental Lakes research area in northwestern Ontario and found those numbers illustrated the report’s overall findings.

Data from four lakes in the region included in the sample showed stable, low chloride concentrations well shy of the EPA’s threshold.

Dugan said those lakes are all located in remote areas without impervious surfaces within a 500 metre range of the shore.

In Lake Simcoe, however, the numbers told a different story.

The lake is situated in a more populous and urbanized area of southern Ontario, which Dugan said likely contributed to a steady increase in chloride levels. She said the amount of chloride in the water had jumped “five-fold” in the past 10 to 20 years.

Dugan said there’s a need for more long-term environmental data across many jurisdictions in order to have a complete picture of the state of freshwater lakes.

The issue of road salt, she said, is one that could be reversed if scientists have enough warning.

“You can flush it out,” she said. “As we improve management practices, we have the potential to remediate these lakes. In some cases quickly, depending on their size.”

Michelle McQuigge, The Canadian Press

Just Posted

Delayed grant decisions could send new Crystal Pool costs soaring

Delays could cost the City of Victoria up to $500,000/month more in construction costs

Campfire ban coming into effect across West Coast

The Coastal Fire Centre says bans will begin on Wednesday

Province delivers notice of unauthorized occupation to Saanich tent city Camp Namegans

A Ministry of Transportation liaison to Camp Namegans delivered a “notice of… Continue reading

UPDATE: Woman hit by car in parking lot 93 years old

Driver of sedan backs into older adult walking through lot

Stolen West Shore vehicle found in ocean off Oak Bay

SUV was submerged 90 feet from shore at Cattle Point

Trudeau asks transport minister to tackle Greyhound’s western pullout

Prime Minister Justin Trudeau says he’s asked Transport Minister Marc Garneau to find solutions in Greyhound Canada’s absence.

Special forces unit to monitor Hells Angels ride on Vancouver Island

Enforcement unit says motorcycle club to hold 35th anniversary ride in Nanaimo

Hub for mental health and addictions treatment opens at B.C. hospital

St. Paul’s Hospital HUB is an acute medical unit that includes 10 patient beds

Saanich Police investigate store robbery

Store video captures image of suspect

Restaurant Brands International to review policy over poaching employees

One of Canada’s largest fast-food company to review ‘no-poach’ franchise agreements

Calgary family’s vacation ends in tragedy on Texas highway

Three people died and four others were injured in the crash

Union construction cost competitive, B.C. Building Trades say

Non-union firms can bid on infrastructure, but employees have to join international unions

Trudeau to shuffle cabinet ahead of Liberals’ team for 2019

Trudeau could lighten the work loads of cabinet ministers who currently oversee more than one portfolio

Greater Victoria Crime Stoppers wanted list for the week of July 17

Greater Victoria Crime Stoppers is seeking the public’s help in locating the… Continue reading

Most Read