Wisconsin salt use: hidden costs, environmental impacts
MILWAUKEE - The Great Lakes are one of the largest single sources of fresh water in the entire world, and people are making it saltier and saltier.
This doesn't happen for an unknown reason. It directly comes from the over-application of salt on roads, sidewalks and driveways. The properties of sodium and chloride once in water prevent ice formation well below freezing – but is the value of ice prevention equal to its long-term impacts?
"It might be cheap to apply, but when we look at the damage it does to our roads, our bridges, our vehicles and vegetation, for every dollar we spend on salt we do $10 worth of damage," said Allison Madison, Wisconsin Salt Wise program manager.
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Salt is fine on impermeable surfaces if it stays there, but once rain and warmer weather returns to Wisconsin, it all rushes into rivers, wetlands and lakes.
"It is a permanent pollutant in our water. So once it is dissolved, the sodium chloride ions split apart and stay in our water forever," Madison said.
According to Wisconsin Salt Wise, salt levels in rivers around Milwaukee are routinely 10 to 100 times higher than what the native ecosystems are used to. As a result, southeast Wisconsin has some of the most salt-compromised rivers in the entire state.
"Every teaspoon of salt pollutes five gallons of water," Madison said.
Salt turns freshwater into salinity habitats closer to brackish water, typical in river deltas that meet the ocean. Native habitats in Wisconsin evolved with hardly any salt, 0–10 milligrams per liter; levels routinely near Milwaukee get to over 1000 milligrams per liter.
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"Just like putting a cucumber in salt water, it turns into a pickle. So we’re kind of pickling a lot of the freshwater organisms that have evolved to live in freshwater streams and lakes." Madison said.
Removing the salt for drinking purposes through evaporation or reverse osmosis is a costly venture ocean communities are dealing with. Once it dries on sidewalks, the crystal structure can also injure your dog's feet.
Are there any positives to salt? Mostly just ice prevention.
An odd meteorologist holding all the salt you need to prevent ice for the average driveway is about as much as a coffee cup
To effectively and efficiently reduce salt on the average driveway, all you need is 12 ounces of it – or the size of an average coffee cup per – ice event. Madison also mentioned, if you can see the salt after a snow or ice storm, then you applied too much and it is not doing its job.
All the environmental impacts are likely to impact you minimally; out of sight and out of mind is how most of our water system works in cities. But what does impact you is what salt does to metal. The increased corrosion of metal will inevitably impact your car – and does even more damage to infrastructure. This is where the cost of salt quickly adds up.
As mentioned earlier by Madison: For every dollar spent on salt, it costs $10 in damage.
Water, Wisconsin's key natural resource, faces storm runoff threat
Wisconsin storm runoff is one of the greatest threats to the quality of Lake Michigan. Millions of people rely on it for freshwater.
The biggest salt users are our cities – and justifiably so. Fortunately, organizations such as Wisconsin Salt Wise help educate cities on the negatives of salt and ways to be more efficient with its use.
Milwaukee is already drastically reducing salt usage. But annually, according to the Milwaukee Department of Public Works, they still use over 35,000 tons of salt. That is three times the weight of the roof of an American Family Field. The piles of salt on Jones Island are huge for a reason.
Ernest Stubbs is a special equipment operator. In his time, he has overseen lots of changes to salt practices in Milwaukee.
View of the roof of American Family Field
"What the city has done over the last five years is they’ve reduced the amount of salt that we spread, we’ve added brine to the salt so as the salt comes out it sticks to the ground," Stubbs said.
A wet solution of salt in a brine form, rather than crystals, can do as much ice prevention while still limiting the overall pound per mile necessary to keep roads safe. It might be impossible to reduce risk on roads.
"As we salt less, the roads may be a little more slippery. All we ask is they slow down, be more cautious and pay attention to their driving," Stubbs said.
Alternatives to salt might not actually be as eco-friendly as they sound. Sand can drastically alter soil composition. Other chemical treatments can be even more damaging to the environment. But according to Stubbs, there is one easy solution to less salt.
Shoveling is the most environmentally friendly alternative to salt, sand, and other chemicals
"Shovel more and salt less," Stubbs said.
Shoveling is the easiest way to reduce refreezing on driveways long term without salt.
In the long term, due to increased salt levels in Lake Michigan, cities such as Milwaukee, Chicago, and Green Bay will have no choice but to reduce their salt usage. The impacts of a saltier Lake Michigan will have ripple effects to our drinking water for generations to come.
Salt usage will never go down to zero in our car-dependent cities. Businesses fearing liability from injuries from a fall, residents just not wanting to put in all the extra work 0and possible reduction in road safety are all factors that need to be followed moving forward with less salt.