Most people don’t make a connection between salting their sidewalks, driveways and roads, and their drinking water, but there is a connection.
Believe it or not, road salts were not used in the U.S. until after 1942. Prior to then, abrasives (ash and cinders, sand) were typically used. After World War II, the expansion of the federal highway system helped facilitate the widespread use of road salts in highway safety. Today, 8 to 12 million tons of road salts are applied on highways every year. In 2016 alone, highway deicing consumed about 44 percent of the 42 million tons of total salt produced in the U.S.
So, what does the salt placed on roads, highways and sidewalks have to do with drinking water? Well, it’s simple. When the snow melts, the road salt eventually runs off into storm drains and ends up in a local stream or river. As a result, sometimes water might taste a little salty immediately after the snow melts. It can also eventually make its way into the groundwater.
Over the past several decades, there has been an increasing trend in the levels of sodium and chloride in fresh water streams and rivers. Salt is very difficult to remove from water without using desalination equipment, which is not a practical technology for most water supplies that are not in desert areas. Salt in streams and other fresh water sources has a major impact on the fish and other aquatic life that cannot tolerate the salt levels. Salt actually sticks around in the streams and rivers and gradually makes them more salty over time.
So, what can we do? We need salt to keep our roads, highways and sidewalks safe. Balancing the need for safety with protecting drinking water supplies has been a challenge water suppliers, environmental organizations, and highway administrators, from the Great Lakes to New England, have been working to solve for some time now. Here are a couple of things you can do because every spoonful of salt counts.
- Use salt brine application prior to a snow event. Many highway organizations already do this, which saves money and makes roads safer.
- Do not dump deicing salts onto storm drains to unblock a frozen drain. If you can’t clear them by hand, use hot water instead.
- Don’t dump left over rock salt and deicing chemicals onto the ground or down storm drains. Talk to your local municipality about the best way to dispose these leftover chemicals.
- Consider alternatives, such as beet juice, to salt pavements and driveways when possible. The sugars in beet juice have been used for deicing in areas around the Great Lakes. These are also typically pet-friendly as well, although, you should always check the label to confirm.
- Try shoveling your sidewalk or driveway first, and let the sun to melt the sidewalk. Use salt on hard-to-melt areas.
The following articles by Steve Corsi from United States Geological Survey provide a more in-depth look at the science of road salt and its impact on streams, rivers and aquatic organisms:
Evaluating chloride trends due to road-salt use and its impacts on water quality and aquatic organisms
River chloride trends in snow-affected urban watersheds: increasing concentrations outpace urban growth rate and are common among all seasons