Toxic road salt lingers in streams year round: Ottawa Riverkeeper

“We didn’t want to find these results, but it is the case that we’re polluting our creeks year-round.”

Published Dec 16, 2023 • Last updated 13 hours ago • 4 minute read

A great blue heron hunts along Nepean Creek, one of the waterways that the Ottawa Riverkeeper found shockingly high levels or road salt, even during the summer months. Photo by Ashley Fraser /POSTMEDIA

The next time you dump road salt on your icy driveway or front walk, the Ottawa Riverkeeper wants you to think about the critters in the creeks.

The harmful effects of road salt — sodium chloride — during winter are well-known, but the non-profit ecological watchdog says the toxin lingers long after winter ends, wreaking havoc year-round on the aquatic ecosystem. It tested creeks and streams in the Ottawa River watershed in July and September and found alarmingly high levels of chloride.

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“We went beyond the winter months because we know that chloride can persist in water,” Riverkeeper Laura Reinsborough said. “We know we’re polluting our rivers and streams in the winter months. Those chloride levels are off the charts — chronic and acute toxicity. But water samples show that high levels persist in July and September.

“We didn’t want to find these results, but it is the case that we’re polluting our creeks year-round.”

Ottawa uses about 185,000 tonnes of road salt each winter. Photo by PAT McGRATH /THE OTTAWA CITIZEN / POSTMEDIA NETWORK

Volunteers with Riverkeeper used electronic monitors to measure the conductivity of water in previous research. In last summer’s study, water samples were sent to a lab for testing to provide even more accurate results.

“Some of the levels are just way over the threshold,” Reinsborough said. “Bilberry Creek in Orléans and Nepean Creek in Nepean. Those two had shocking levels of chloride.”

Nepean Creek runs west to east on the south side of Viewmount Drive and drains into the Rideau River. Bilberry Creek runs north from Innes Road, entering the Ottawa River about three kilometres upstream from Petrie Island.

Road salt melts ice by lowering the freezing point of water. It breaks into ions of sodium and chloride when in solution. The sodium dissolves and is carried away yand causes little harm, but the chloride ions persist in place. Chloride disrupts the breathing and reproductive abilities of small creatures that inhabit the stream bank: frogs and other amphibians, insects and fish.

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The wildlife were out in full force along Nepean Creek on Saturday. Photo by Ashley Fraser /POSTMEDIA

“All the little hard-working critters that live in stream bank are the most affected and they tend to be very vulnerable,” Reinsborough said. “Think about salamanders. Think about frogs. A lot of fish are laying their eggs there, so those very vulnerable life stages are affected. Mussels and insects, too. They struggle to breathe, they struggle to reproduce — these are two critical functions.

“And it’s the base of our food web for most of our aquatic life. If we’re affecting the little critters in stream bank, then we’re affecting the entire river.”

Ottawa Riverkeeper Laura Reinsborough. Photo by Blair Crawford /POSTMEDIA

The City of Ottawa uses about 185,000 tonnes of road salt annually, but has been trying to reduce its dependence. This year the city partnered with Riverkeeper to produce a video to train operators about salt’s harmful effects.

But it’s not just roadways that are a source for salt. Homeowners and businesses use salt on driveways and parking lots. In winter, when the ground is frozen, rain or meltwater can carry salt a great distance before it enters the water.

“We know road salt is effective at melting ice, so we advocate for its use. It’s a great tool,” Reinsborough said. “The issue is that Canadians overuse salt. We use it when it’s not the right application. We use it when the temperature isn’t amenable.

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“Canadians tend to have a lot of pride in the way we handle winter,” she said. “But this is an area for improvement.”

The wildlife were out in full force along Nepean Creek on Saturday. Photo by Ashley Fraser /POSTMEDIA

Cutting the salt habit

Want to cut your use of road salt? Start by using it the right way.

Watch the temperature: Salt is ineffective when the temperature is below -10 C. “If it’s colder than that, it’s just not going to work,” Ottawa Riverkeeper Laura Reinsborough said. And don’t overdo it. A coffee cup full of road salt is enough to melt ice on a two-car driveway, she said.

Melting, not gripping: “We advocate that people use it to melt ice, but not for traction,” Reinsborough said. “There are other tools for that. You don’t have to put a thick blanket of salt down. It’s not meant to be the grip you apply.”

Sand and kitty litter can be used to take away the slipperiness. So do spiky cleats that can be affixed to your footwear. Proper winter boots with aggressive soles provide better grip and are safer on ice than normal street wear.

Manage your expectations: Do you scrape away the snow to get that satisfying bare driveway look? That can just make things even more slippery. “When you shovel, don’t expect that you’ll always get down to a bare driveway,” Reinsborough said. “Leave a layer of snow and it often provides a better grip. Shovel when it’s slushy so it doesn’t refreeze.”

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Redirect drain pipes so they don’t send meltwater onto your walkway. Pile snow in such a way that the meltwater drains away from steps, sidewalks and driveways.

Be winter ready: Snow tires provide better traction when roads are slippery, and remember to give yourself plenty of time to get to where you’re going to prevent slips, falls and accidents.

Source: Ottawa Riverkeeper and the City of Ottawa