• 07 Nov 2017 7:58 AM | Smart About Salt (Administrator)

    If you live — and drive — in a northern or mountainous climate, you’ve seen highway trucks spreading loads of rock salt on snowy highways to melt the ice. But where does the salt go?

    A lot of it ends up in our lakes and streams. A recent study of 371 lakes in North America — most in the northern states and southern Canada — showed chloride concentrations rising in more than a third. More than two dozen were nudging toward levels harmful to aquatic life. Extrapolated to all lakes in the U.S. northern Great Lakes and Northeast regions, about “7,770 lakes may be experiencing elevated chloride concentrations, likely due to road salt runoff,” the study concludes.

    U.S. road maintenance departments have been spreading salt on streets and highways to melt snow and ice since the 1940s, but the use of salt skyrocketed over time — from 0.15 metric tons (0.16 tons) per year during the 1940s to about 18 million metric tons (19.8 million tons) per year today. Road salt use is common and growing throughout Canada, Europe, Japan, China and even South America. As much as 60 million metric tons (66 million tons) may be applied worldwide each year. Unlike chemicals that break down into less harmful compounds, road salt persists and may remain in water and soil for years, until it eventually is diluted and carried away by moving water.

    Despite the ever-greater use, road salt’s effects on streams, lakes and groundwater have been largely ignored until recently. As recently as 2014, when biologist Rick Relyea began studying the effects of salt-laden runoff at Rensselaer Polytechnic Institute, “the world of science didn’t pay very much attention to the impacts of road salt on water,” he says. “Now we’re paying much more attention.”

    Recent research is showing that in many waterways, chloride is on a persistent upward trend, with potential to harm aquatic communities and even impair drinking water.

    Neither Relyea nor other researchers suggest highway salting crews should sacrifice public safety for the sake of healthy streams and lakes, but they say there are ways to cut salt use without impairing winter road maintenance.

    Same Old Salt

    To melt ice and prevent the accumulation of new ice on winter roads, highway crews apply salt. In the U.S., salt use is heaviest in the Midwest, Great Lakes region, New England, Alaska and the northern Appalachians. Road salt is mostly sodium chloride, the same stuff you sprinkle on food, but in coarse granular form. When it dissolves in slush it lowers the freezing point, causing ice to melt. For the same reason, salt is spread on sidewalks and parking lots.

    More expensive alternatives, such as magnesium chloride and calcium chloride, work better at temperatures below 15 °F (–9.4 °C). “But they still have chloride, so theyre not any better for the environment,” says Brooke Asleson, metro area watershed project manager for the Minnesota Pollution Control Agency (MPCA).

    Chloride is the component of salt of greatest concern for aquatic life. Chloride has been shown to be benign at low concentrations, but as concentrations increase salt can kill plankton, disrupt aquatic communities, increase algae blooms and stunt fish. The U.S. Environmental Protection Agency has set a long-term threshold for aquatic life of 230 milligrams per liter. Canada’s guideline for long-term exposure is 120 mg/liter. (For comparison, seawater has a chloride concentration of nearly 20,000 mg/liter.)

    “Just that contrast makes you realize we dont have a good idea of what concentrations are really harming our environments,” says Hilary Dugan, assistant professor at the University of Wisconsin–Madison Center for Limnology and lead author of the North American lakes study, published this spring in the Proceedings of the National Academy of Sciences.

    In many cases, the U.S. and Canadian thresholds are already being exceeded. Keeping freshwater “fresh,” according to Dugan’s paper, “is critically important for protecting the ecosystem services freshwater lakes provide, such as drinking water, fisheries, recreation, irrigation, and aquatic habitat.”

    Toll on Waterways

    Dugan’s paper tracks long-term chloride concentrations in North American lakes with detailed available records. Most were in what researchers called the “North American Lakes Region,” which includes Connecticut, Maine, Massachusetts, Michigan, Minnesota, New Hampshire, New York, Ontario, Rhode Island, Vermont and Wisconsin.

    Mean chloride levels ranged from hardly any at all to 240 mg/liter, above both U.S. and Canadian standards. About 10 percent in the lakes region exceeded 100 mg/liter. And perhaps most concerning, slightly more than a third of the lakes overall showed persistent upward trends in chloride concentrations.

    Dugan attributes the increased levels to factors such as more roads, bigger roads, more traffic, and more parking lots. The lakes with the greatest long-term concentration of chloride were those with the greatest proportion of impervious surfaces, such as roads and parking lots, in their watersheds. But it didn’t take a lot — as little as 1 percent road surface within a half-kilometer (third of a mile) of the water body. “It was a surprisingly small percentage of impervious surface that led to long-term increases in chloride,” says Dugan. “I’m not sure that anyone expected that percentage to be so low.” According to her study, 27 percent of large lakes in the United States have more than 1 percent impervious surfaces nearby.

    Much of the salt runs off these surfaces shortly after it’s applied or with spring melt. But some of it seeps into soil, creating a “reservoir for chloride,” Dugan says. “Even if we stopped applying road salt today, theres a high likelihood that chloride levels [in lakes] would continue to increase for awhile as some of those chlorides flush out of soils.”

    Dugan’s big-picture look at North American lakes squares with Asleson’s finer-grained analysis of Minnesota’s Twin Cities, in which 19 lakes currently exceed the water-quality standard for chloride. And chloride concentrations were increasing in most Twin Cities lakes.

    “When you have a watershed area that has a road density of 18 percent or greater [in the entire watershed], that’s where you’re most likely to see water quality problems because of winter deicing salt,” says Asleson.

    Trophic Cascades

    While chloride is not yet poisoning our waterways, chloride does have the potential to change aquatic communities, stunt fish growth, aid exotic species and even affect tourism.

    Rick Relyea is director of Rensselaer’s Jefferson Project at Lake George, a deep, clear 32-mile (51.5-kilometer)-long finger of water in northern New York. Relyea and colleagues monitor the lake and conduct experiments in artificial habitats to determine the effects of chloride and other components of salts on aquatic life.

    “When some activity like road salt harms one species, it’s usually not the end of the story,” says Relyea. “It indirectly affects a lot of other species.”

    In Relyea’s study, high road salt concentrations induced a “trophic cascade,” reducing zooplankton and producing an upsurge in their food, phytoplankton, which seemed to thrive in the high salinity.

    Relyea’s team also found that exposure to salt drove zooplankton evolution toward salt tolerance. “Those zooplankton populations that were knocked down by a lot of salt actually bounced back and started doing really well,” he says. That tolerance was passed on to subsequent generations. “That’s really the hopeful message,” he says. “Its not that we should ignore the issue. Its hopeful that we could buy some time until we solve the issue.”

    In another study, tadpoles raised in salty water became male rather than female frogs at a 10 percent greater rate than expected. The team doesn’t understand the underlying mechanism, says Relyea, but “the explanation is clearly that we have converted some of the females into anatomical males while they are tadpoles.”

    Relyea found that salt levels in Lake George are rising but are still far too low to impair aquatic life. Streams in the watershed are a different story. Chloride concentrations spike to levels 100 time greater that those found in lakes, and remain high through the year as chloride leaches from soils. “Thats probably true throughout the northern U.S. and Canada,” Relyea says.

    Other research has shown that salt can affect trout growth. Calcium chloride had the greatest effect of common road salts, at chloride concentrations of 860 to 3,000 mg/liter. The effect was greatest at the highest concentration, reducing weight of rainbow trout by more than 30 percent. “If you grow more slowly, you can be more susceptible to predators, it will take you longer to be reproductive, you will lay fewer eggs,” says Relyea. “Growth for a fish is everything.”

    Relyea says the sodium in salt can trigger the release of other metals from soil that run into waterways. Released calcium can favor some species over others. “Now you make it easier for some invasive species, like say Asian clams, zebra mussels, various snails — you make it easier for them to get a foothold if they ever arrived in your lake,” he says.

    Road salt also damages and kills vegetation, though the effects are concentrated within 200 feet of roadways.

    High salt use can cause problems for humans, too. Salt seeps into groundwater, raising the salinity of drinking water. In Madison, Wisconsin, where Dugan lives, “Thats a huge concern for municipalities and water treatment plants,” she says. And according to research by the EPA and U.S. Geological Survey, high chloride increases the corrosion of poisonous lead from old water pipes.

    Low-Salt Solutions

    Researchers have experimented with salt substitutes such as beet juice, which lowers freezing temperature and melts ice as the sugar it contains dissolves on the road. But the sugar is a fertilizer that feeds algae growth.

    “In most lakes, we already have enough nutrients going in, particularly in clear, infertile lakes. Theyll be more green and less transparent and less aesthetically pleasing to most people,” says Relyea. “The less transparent the water becomes, the less valuable the attraction to tourists and the less income that comes into communities.”

    Many states regulate road salt storage. But many do not. And none specifically regulates the application of road salt, says Asleson. Instead, road maintenance departments are encouraged to use best management practices. New Hampshire offers a voluntary certification and training program for private applicators maintaining large surfaces such as parking lots. Likewise, Canada has developed a “code of practice” for road salt use.

    The MPCA has created a web-based tool for public works departments and other winter maintenance pros to help evaluate their own programs, from small details (Do they overfill their salt and sand trucks?) to big issues (Do they stockpile road salt outside?). “Weve looked at every aspect that we could with this core group of winter maintenance experts to find every opportunity possible to reduce salt use,” Asleson says.

    Asleson thinks the biggest single change to use less salt is switching to liquid solutions. The brine spreads more evenly, stays put and begins working immediately because the salt is already in solution. As a result, spraying liquid brine is more effective while using less salt. Asleson says cities that have switched to tanker trucks have reduced salt use by up to 70 percent and paid back their equipment investment in a year or two.

    In northern New York, Relyea says, local governments have been adopting so-called live-edge plows. The plow blade, rather than being solid, is divided into short independently moving sections that follow the contours of the road and better remove snow and ice. That leaves less ice to be removed by chemicals, reducing salt usage. “You still salt, but you dont salt as much,” he says.

    “The salt issue is biologically very complex, but I think it has motivated people to think about how we can simultaneously have safe roads and healthy ecosystems,” says Relyea. “If communities could have the ability through technology to purchase less salt, to salt fewer times, pay less truck driver time and help their lakes that are big tourist attractions, it really can be a win-win for everybody involved. It’s not really about posing the health of ecosystems against public safety.”

    Greg Breining Journalist and author

  • 03 Aug 2017 2:29 PM | Smart About Salt (Administrator)

    We might all be enjoying summer weather but winter is right around the corner. Mindful of current research the Smart About Salt Council (SASC) has been busy working with industry, government and other stakeholders to develop a new online training program for winter maintenance contractors, facility owners/operators and others that provides education on leading practices in winter maintenance.

    “The new online training is available in English and French and complements our existing award-winning in classroom efforts that have been so successful” said Eric Hodgins, a Professional Hydrogeologist and Chair of the Board of Directors for the Kitchener-based organization. “Obviously safety is paramount, but we’ve seen how climate change and knowledge-gap are combining for magnifying negative impacts on our freshwater resources”.

    A partnership effort by industry and government in  2009 led to the creation of the Smart About Salt Council, a not-for-profit organization dedicated to protecting our freshwater resources from the over application of salt. The Smart About Salt Council is unique to Canada offering win-win education and certification that seeks to engage industry and the public to adopt leading practices in winter maintenance. The new format will improve access to training which is needed in light of  recent University research which confirmed that winter salt is damaging lakes and rivers.

    “We help those facility owner and operators work with their contractors and others so that facilities and the public are protected. It’s about collaboration and awareness so that everyone concerned benefits, including our water resources” noted Hodgins.

    For more information about the Smart About Salt Council (SASC) and its award-winning training programs please visit

  • 27 Jul 2017 12:29 PM | Smart About Salt (Administrator)

    Today the Ontario Ministry of the Environment and Climate Change (MoECC) has released the 2016 Minister’s Annual Report on Lake Simcoe on the ministry’s website.  This is Ontario’s fifth report on Lake Simcoe detailing the continuing progress we are making in implementing the Lake Simcoe Protection Plan. 

    The report highlights some of the ministry's key accomplishments in 2016 including:

    • promoting methods to reduce the amount of winter road salt entering the watershed by in part supporting Smart About Salt Council's (SASC's) development of an online education faciltiy;
    • supporting the Chippewas of Georgina Island First Nation to address climate change based on traditional ecological knowledge;
    • piloting the use of drones to monitor fish development with high resolution photography and thermal imaging; and,
    • assisting farmers who voluntarily implement projects that use water and energy more efficiently.

    The Report also includes the advice that Minister of Environment and Climate Change received in 2016 from the Lake Simcoe Coordinating and Lake Simcoe Science Committees.

    To view the report, follow the link below:

  • 19 Jul 2017 12:28 PM | Smart About Salt (Administrator)

    Overlap is working with the Region of Waterloo to develop a salt reduction plan to protect the region’s water quality.  We are interested in hearing from you—a current or future Smart About Salt member—about your winter salt use.  Please contact Patrick Boot of Overlap at for more information about this initiative.

  • 12 Jun 2017 10:15 AM | Smart About Salt (Administrator)

    'Not having the information to measure the actual health of a majority of watersheds is extremely concerning'

    By Margo McDiarmid, CBC News

    Canada may be home to 20 per cent of the world's freshwater, but there is no national system to collect or share information about the health and quality of Canada's watersheds, according to a new national assessment of Canada's rivers. 

    The report by WWF-Canada warns that Canada's watersheds are facing serious threats from pollution, climate change and loss of habitat.

    "I think that's a result that Canadians, when they learn it, will be deeply concerned about," said David Miller, president of World Wildlife Fund-Canada in an interview with CBC News.

    "We have a pretty good handle on what the threats are and potential impacts of those threats, so not having the information to measure the actual health of a majority of watersheds is extremely concerning."

    Canada has five major ocean watersheds: the Arctic, the Atlantic (which includes the Great Lakes and the St. Lawrence River), Hudson Bay, the Pacific and the Gulf of Mexico. Major rivers in these regions drain into those ocean watersheds. Major rivers are fed by smaller rivers called sub-watersheds. 

    The study looked at 167 sub-watersheds. It found that almost two-thirds are lacking in the crucial information needed to get a basic picture of water quality and river health.

    Lack of complete data

    The report singles out areas that are particularly short of detailed information: the North and South Saskatchewan watersheds, the Peace-Athabasca watershed and, surprisingly, the Great Lakes and the Ottawa River.

    The lack of information is "surprising, considering these watersheds are home to a significant portion of the country's population, industry, agriculture and well over 100 at-risk species," said the report.

    Miller says part of the problem is a lot of water testing and monitoring is hit and miss.

    "It's a very patchy system," he said. "For example, if the urban area of Calgary is measuring the health of the Bow River, but upstream is not being measured, you don't have a proper and full picture."

    WWF-Canada was able to get information about the health of 67 sub-watersheds from some publicly available sources including universities and Statistics Canada.

    That data showed about 60 per cent have poor or fair water quality. One third had their flow interrupted by dams, roads or railways.

    Threatened by pollution, loss of habitat

    The report also looked at threats facing the 167 sub-watersheds. It found that one third of rivers have high or very high levels of stress. They are being damaged by pollution, by the loss of habitat often caused by homes and buildings constructed too close to the water and by climate change. 

    A spokesperson for federal Environment Minister Catherine McKenna says water is a shared responsibility. Marie-Pascale Des Rosiers said in an email that the federal government works with provinces, territories and municipalities and Aboriginal people to protect water.

    She added that the government of Canada has invested millions of dollars into freshwater protection in the last two budgets.

    That includes $197.1 million in 2016 to increase ocean and freshwater research, $3.1 million to improve shore and ecosystem health in the Great Lakes and $70.5 million in the 2017 budget to protect water in the Great Lakes and Lake Winnipeg basins. The federal government also has an 11-year plan to improve wastewater systems across the country.

    "Our government has a comprehensive approach to help ensure clean, secure and sustainable water resources for present and future generations," said Des Rosiers.

    Need a way to track water quality

    But WWF-Canada's Miller argues one national system is needed to properly track the health of fresh water and the impacts from human activity.

    "Like most Canadians, I have an image of our  country as a haven of fresh water," said Miller. "When I started canoeing I could dip my cup in a lake in Algonquin Park and I could drink it without treating it and that's not true anymore." 

  • 31 May 2017 1:09 PM | Smart About Salt (Administrator)

    Date:May 31, 2017

    Source:Virginia Tech

    Summary:Routing runoff contaminated with road salts to stormwater ponds actually resulted in plumes of highly contaminated groundwater moving from the ponds to streams, report scientists.

    In winter, most municipalities rely on chemicals to melt ice and keep roadways and parking lots clear and safe for travelers. The most common chemical used, owing to its low cost and its effectiveness at low temperatures, is sodium chloride, commonly referred to as road salt.

    Researchers at Virginia Tech and Towson University in Maryland are concerned that the types of chemicals used to treat roads in winter, particularly road salts, are not being effectively absorbed by soil and plants as intended by mitigation measures and may be reaching waterways.

    Stormwater management practices are designed to intercept water runoff from roads and parking lots before pollutants reach surface waters. Detaining runoff in retention ponds can reduce flooding, increase the amount of water that is absorbed into the ground, and allow pollutants to bind to sediments in the ponds or be absorbed by algae and plants instead of traveling to streams and wetlands where they may harm wildlife and human health.

    The research team recently completed a study, published in Environmental Science and Technology, to determine how well current stormwater management practices mitigate the effects of road salts and how those salts might be impacting both the surface waters in streams and ponds, and the groundwater that many citizens using well systems rely on daily.

    "We know that surface waters in many areas are becoming more saline and that salt levels have been rising steadily for at least the past 30 years in reservoirs that provide water for Baltimore," said Joel Snodgrass, professor and head of the Department of Fish and Wildlife Conservation in Virginia Tech's College of Natural Resources and Environment. "However, we know little about the effectiveness of stormwater management practices in reducing inputs of salt to surface waters."

    The researchers tested water samples from stormwater ponds in Baltimore County and surface waters in the county's Red Run watershed to compare the concentrations of sodium and chloride ions in groundwater between stormwater ponds and streams.

    Water in the ponds gradually soaks into the ground and moves downslope toward streams. If the stormwater ponds were working effectively, Snodgrass explained, he and his team could test the groundwater between the ponds and streams and expect to find very little sodium chloride because it would have been retained in the ponds.

    In fact, the opposite seemed to be true. The researchers discovered that routing runoff contaminated with road salts to stormwater ponds actually resulted in plumes of highly contaminated groundwater moving from the ponds to streams.

    In addition, high levels of contamination were not only present during winter months but in the summer months as well, meaning that some of the road salts are being retained within the groundwater close to the surface and released to streams little by little.

    "Current stormwater management practices may help slow the movement of road salts to streams, but they don't completely stop it from getting there," Snodgrass explained. "On top of that, the road salts are entering these bodies of water in a fashion that causes salt levels in streams to remain elevated year-round."

    Elevated salt levels in groundwater and surface waters can have negative impacts on wildlife and humans. If salt levels continue to increase in freshwater areas, many fish and amphibians will stop breeding and eventually die because their bodies cannot adjust to the change.

    "You're basically putting these animals in a desert, because they can't regulate the salt in their bodies and get enough water to balance it out," Snodgrass said.

    On the human side, added salt in the water system can change the taste and color of well water and eventually cause wells to stop providing potable water.

    "People may end up drinking water containing sodium levels that exceed those recommended for people on low-sodium diets. Municipal water supplies may also become contaminated and require treatment to lower sodium and chloride levels before distribution," Snodgrass said.

    There are also economic implications to consider.

    "Some counties are already reimbursing people for the costs associated with replacing contaminated water wells," he added.

    So what can be done?

    According to Snodgrass, the answer is complicated. More research will have to be conducted to analyze the costs and benefits associated with using road salts. Snodgrass and his team plan to continue researching how road salts and other chemicals affect wildlife and the environment, while other researchers are exploring the effectiveness of alternatives to road salts and their potential effects on the environment and human health.

    "It's a balance sheet we're looking at between economics and the environment and human health," Snodgrass said. "This is a complex problem that's going to take an interdisciplinary team to tackle, including sociologists, economists, and chemists, as well as biologists and ecologists."

    Story Source:

    Materials provided by Virginia Tech. Note: Content may be edited for style and length.

    Journal Reference:

    1. Joel W. Snodgrass, Joel Moore, Steven M. Lev, Ryan E. Casey, David R. Ownby, Robert F. Flora, Grant Izzo. Influence of Modern Stormwater Management Practices on Transport of Road Salt to Surface Waters. Environmental Science & Technology, 2017; 51 (8): 4165 DOI: 10.1021/acs.est.6b03107

  • 04 May 2017 2:03 PM | Smart About Salt (Administrator)

    As part of its ongoing efforts to educate about freshwater resources the Region of Waterloo has developed a new video themed around winter maintenance. View it now online at

  • 12 Apr 2017 12:02 PM | Smart About Salt (Administrator)

    Road salt in runoff from melting snow is threatening the health of freshwater lakes, according to a new study in eastern North America

  • 12 Apr 2017 9:00 AM | Smart About Salt (Administrator)

    Salt might make our roads safer, but it's also threatening hundreds of lake ecosystems around North America.

    Lakes near roads or parking lots are the most at-risk, but even a small amount of pavement close by increases a lake's salination, according to a study published Monday in the Proceedings of the National Academy of Sciences.

    The study looked at 371 freshwater lakes in the Midwest and Northeastern U.S. It found that as little as one per cent of impervious land cover — roads, sidewalk or any other hard surface that prevents salt from soaking into soil — meant that a lake would have a high chloride concentration. Over the past few decades, 44 per cent of the studied lakes got saltier.

    “These results are likely an underestimation of the salinization problem, as a number of regions with heavy road salt application, such as Quebec or the Maritime provinces of Canada, had no long-term lake data available,” study co-author Sarah Bartlett said in a release from the University of Madison-Wisconsin.

    Road salting became a standard practice in the '40s, the study notes. Over the following 50 years, the amount of salt used in the U.S. increased from 0.15 metric tons per year to more than 18 million.

    In Canada, an average of five million metric tons of road salt was used every year between 1995 and 2001.

    In the U.S., 27 per cent of large lakes are surrounded by at least one per cent of roadway or sidewalk, meaning that they are at a high risk of hurting local ecosystems, drinking water and fisheries. The study estimated that 7,770 lakes are in trouble across North America.

    Salty drinking water can hurt people with kidney disease, and lakes with high salinity slowly kill off freshwater fish.

    Cities trying to use less salt

    The study recommended that local jurisdictions set up long-term monitoring to keep freshwater lakes "fresh."

    Canada's government published a code of practice for reducing the use of road salts in 2004.

    Toronto reduced its salt use by a mean of 37,000 tons over two years after implementing a new training program for employees. Municipalities like Cowansville, Que., and Williams Lake, B.C., have started using beet juice to reduce the salt's environmental impact.


    However, cities aren't the only problem.

    “What I don’t think people realize is that a large quantity of road salt – in some areas more than 50 percent – is applied by private citizens and businesses, to sidewalks and parking lots, and there has to be an effort to reduce this load as well," researcher Hilary Dugan told the University of Madison-Wisconsin.

  • 11 Apr 2017 6:19 AM | Smart About Salt (Administrator)

    Melting snow from roads and parking lots is threatening thousands of lakes in North America.  

    A new study of 371 lakes in eastern North America shows they're getting saltier because of runoff from the salt used to melt winter snow and ice.

    Canadian Hilary Dugan, a limnologist at the University of Wisconsin-Madison, was lead author of the study.

    Dugan said the study found that the closer a lake is to roads or parking lots, the greater the threat to the quality of the lake water. Even a small amount of pavement causes salt to run off and seep into the ground and eventually get into the lake.

    "I really thought you'd have to be in a dense urban environment to see that result, but surprisingly little urban environment impacts these lakes," said Dugan in an interview with CBC News.

    "You think about driving in rural and remote environments and as you are driving you can see lakes beside the highway, and just the presence of that highway puts those lakes at risk."

    The study is the largest of its kind so far into the effects of road salt on lakes.

    It was conducted by 15 researchers who are part of the Global Lake Ecological Observatory Network and published in the Proceedings of the National Academy of Sciences.

    The study looked at lakes in Connecticut, Maine, Massachusetts, Michigan, Minnesota, New Hampshire, New York, Ontario, Rhode Island, Vermont and Wisconsin. Quebec and the Atlantic provinces were left out because they didn't have enough long-term lake data to be included in the study.

    The research did not include the Great Lakes, which have already been the subject of multiple studies.

    The researchers looked measurements of chloride (salt) levels in lakes that have been collected by federal, provincial and state governments for a least a decade.

    They compared that data with remote lakes that aren't close to roads.

    "Almost all of the lakes situated near a major roadway showed long-term increases in chloride concentrations," said Dugan. 

    "When you think about road salt being thrown down on roads or sidewalks or parking lots, once that road salt is applied in the environment, it's not removed. It's either stored in the soil or it's going to be flushed into nearby streams and rivers and lakes."

    "So any road salt is eventually going to end up in our waters."

    Lake Simcoe salt levels show fivefold increase

    Dugan points to Ontario's Lake Simcoe as example. In the 1970s, the large lake had a salt concentration of 10 micrograms of chloride per litre of water. It's now 50 micrograms per litre — a fivefold increase. 

    "Lake Simcoe is huge, it covers 750 square kilometres, and so you can imagine that if we are talking about a small lake, one that's only a kilometre or less in area, you can rapidly increase chloride concentration over one hundredfold what its background concentration would be."

    The study predicted that if the results were extrapolated to all the water bodies in the North American lakes region, about 7,770 would be at serious risk.

    Saltier lakes can affect the entire water ecosystem, from the fish to the invertebrates they eat to tiny plankton. Salt can also make the lake more susceptible to invasive species and harmful forms of algae. Dugan said it takes a lot of salt to kill a lake, but a small amount can make it sick.

    Canada reducing road salt use

    It's estimated that 23 million tonnes of salt based de-icer are applied to North American roads every year. Environment Canada estimates that between 1½ and four million tonnes are used in Canada every winter, depending on the severity of the weather. 

    Since 2001, Canada has been trying to reduce the use of road salt, installing a voluntary code of best practices to get municipalities and cities to cut down. About three-quarters of all municipalities have adopted the code.

    For example, Toronto has managed to reduce its use of road salt by 25 per cent.

    But a lot of people still aren't thinking of alternatives, said Lee Gould, executive director of Smart About Salt, a non-profit group set up to encourage alternatives to winter salt.

    "It's not uncommon for people to expect bare tarmac in January and February," said Gould in an interview with CBC News. 

    Gould said a lot of private business and shopping malls employ "outdated practices," such as applying salt and chemical de-icers to get rid of snow instead of simply plowing it.

    He said the key is get people to think about how much salt they're using and when. 

    Dugan said most municipalities are doing a good job of that. The problem is homeowners and private businesses.  

    "In many cases more than 50 per cent of what is applied is actually put down by private citizens and businesses and that is the road salt that you see piling up on sidewalks and parking lots.

    "So we need to better educate ourselves in understanding that it takes very few salt crystals to effectively melt snow and ice." 

    The study concludes that if the current practices don't change, many lakes in eastern North America will surpass the scientifically recommended safe salt level within 50 years.

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