by TThe first blizzard of winter will be a fit for some residents of Davenport, a city of 100,000 people on the banks of Iowa’s Mississippi river, with an average of 30 inches of snow falling throughout the season. Like many towns in the US and Canada, Davenport pours large amounts of rock salt onto their roads each year, melting the ice and making conditions easier for drivers. This year, however, residential streets on the northwest side of the city will be left without salt.
Nicole Gleason, public works manager, says the lawsuit, where residents may have to traverse several blocks from snowy roads to reach main arteries, is Davenport’s attempt to “find a balance” between road safety and its growing list of road salt issues. .
Ice-free roads may be good for drivers, but scientists warn that salt seeps into lakes and rivers, including the Mississippi, killing wildlife and posing health risks to humans. Salt also erodes asphalt and metal, causing about $5 billion in damage to roads and cars each year. And it triggers accidents by pulling deer and moose onto highways to lick.
Still, North Americans are addicted to road salt. Road crews have been spilling more material than ever since cars and highways began to proliferate in the area in the 1950s. According to the U.S. Geological Survey, the amount of salt used on U.S. roads has increased from 1 million tons in 1954 to 10 million tons in 1985 and nearly 24 million tons per year in 2019 as drivers demand increased levels of safety and comfort. “Fifteen years ago, it was not common practice to wait for the pavement to dry after the snow,” Gleason says. “But somehow, the idea took hold that everybody should drive in the winter as if it were summer.”
The search for an alternative to salt
As the lawsuit against road salt has grown stronger over the past decade, scientists and local governments have sought to find a less harmful alternative. However, success was limited. Chemical solutions have proven expensive and carry their own environmental risks, such as reduced oxygen levels in the water or damage to leaves. Sand works for driveways or small areas where it can be swept easily, but if used on a larger scale, it can clog drains, contribute to fine particulate air pollution, or damage vehicles. Cheese brine has been used to melt snow in Milwaukee, Wis. since 2013—it easily uses waste from the local dairy industry. But the amounts available only put a small notch in salt needs. Beet juice has proven effective in many places, but it releases sugar into the waterways, feeding harmful algal blooms that are just as dangerous to wildlife as salt. As a result, it can really only be used as an additive to salt.
“People always want a silver bullet, but it’s a multidimensional problem with many parts,” says Xianming Shi, a lead researcher and professor of alternative defrosting methods at Washington State University. “I don’t think we’re going to find a magic solution.”
A utility worker sprinkles salt on sidewalks in Reading, PA, during a blizzard on February 18, 2021.
Ben Hasty—MediaNews Group/Reading Eagle/Getty Images
With the dream of completely replacing the stored salt, many states and cities are focusing on reducing it. Public information objections can be helpful. For example, this winter in Sudbury, a city of 300,000 in Ontario, is distributing plastic cups to change the way residents salt their driveways. According to the label notes, 12 oz cups hold enough salt to safely defrost 10 square feet of pavement, or 500 square feet—that’s far less than many people think they need. The cups also remind people not to salt them when it’s colder than -12°C (10.4°F), because that’s definitely not going to work.
Road crews mobilized
Authorities are also trying to make it easier for road crews to reduce salt. Minnesota is a leader here. Since 2016, the state has been running a “smart salting” program to train state road crews and specialty maintenance workers to apply salt without wasting it, helping organizations reduce their use by 30 to 70%, according to the state pollution control agency. Minnesota also has policies that limit the distribution of salt on residential streets, as Davenport tried. The state legislature is now considering a bill that would protect professional salt applicators and homeowners from legal liability from accidents if they use too little salt;
The most effective way to reduce salt may be a more fundamental change in how it’s applied. Spraying the roads with salt water (roughly one part salt to three parts water) in the hours before it starts to snow prevents the formation of ice in the first place. This proactive approach reduces the need for salt by between 23% and 70%. There are challenges: you need very accurate weather forecasts, and the equipment used to mix and transport the brines is more expensive than conventional salting. But over the past five years, the rising cost of salt and growing awareness of environmental threats have convinced many cities, including New York, Des Moines, and Philadelphia, to use salt water instead of salt whenever possible.
For Davenport, which is currently trying to use brine wherever possible and adding 5% beet juice to its de-icing solutions to meet some of its salt needs, the next frontier is trying to change public expectations of how clean roads should be. City councilor Judith Lee, who proposed the trial, says some voters have expressed anger at the idea of not salting. “They thought we’d let them slide on the ice, and of course that’s not the case,” he says, noting that road crews will still attend the trial area if dangerous conditions develop. “But when we talk about all the reasons we want to reduce, people begin to understand.”
Researcher Shi hopes that more local and state governments will find ways to rein in their salt addictions. If they don’t, he warns, 50 years from now the sodium content of many water sources could reach levels unsafe for human consumption. “For this generation, convenience – driving fast from point A to point B – could mean our grandchildren are drinking salt water.”
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