Reducing road salt usage protects the environment and trees - The Washington Informer

Landscape plants, especially trees lining sidewalks, are the most in danger of experiencing salt damage following winter weather. Urban canopies are crucial to a city’s environmental health, so they must be considered when deicing roads. (Mya Trujillo/The Washington Informer)

Since 1938, U.S. residents have used rock salt to prevent roads from freezing after winter storms, and while it is necessary to ensure public safety in icy conditions, homeowners and winter maintenance staff must be mindful of the amount they use.  

Although rock salt is an effective tool, causing ice to melt and creating friction between car tires and the pavement, the excessive application of sodium chloride on roads can adversely affect the environment, leaving roadside and landscape plants vulnerable to damage. 

According to the Rutgers Cooperative Extension, sodium-chloride-based ice melt can easily weaken a tree, making it more susceptible to losing branches or contracting diseases. Further, 35% of Washington’s 1.9 million trees account for the city’s urban tree canopy, the most imperiled as they grow adjacent to areas where road salt is most commonly distributed.

If too many trees are weakened due to salt use, the city’s air quality is at risk of decreasing, while pollution could increase. Being reckless with deicers, jeopardizes both the climate control and the amount of oxygen trees offer.

“We have to find that balance of protecting the public while also protecting our green infrastructure,” said Lou Meyer, an arborist with Davey Tree. 

Negative effects are more immediately visible in evergreen trees, as their green color quickly pales when exposed to excessive salt. 

However, signs of distress due to ice melt are less obvious in deciduous trees since they lose their leaves during the winter months. When they sprout anew in the spring, the trees’ leaves will often be yellow rather than green. 

“As the leaves pale out, they don’t have as much chlorophyll, so they don’t photosynthesize as much, [and] they don’t create as much food,”  Meyer said. “If they don’t create as much food, it weakens the tree, and it has less energy to put into reproductive systems, health systems [and] growth systems.” 

Aside from changes in leaf color, other negative effects on trees from salt include bark discoloration caused by residual salt on the trunk, and canopy dieback– the death of twigs and branches. This deicing method dries out the soil, disrupting reproduction and growth as water cannot easily reach the plant’s roots. 

A few preventative measures can be taken to protect trees and shrubbery from rock salt damage. Constantly watering trees is already an essential caretaking procedure, especially in the winter, but also helps flush out and disperse surplus salt. 

Meyer has discovered a sustainable way of watering his trees. 

“I have a dehumidifier running in my basement all the time, [so] I pour that water into a five-gallon bucket,” he told The Informer. “It takes three full dehumidifiers to fill that bucket, and then I’ve got five gallons of water that has to go somewhere, so instead of throwing it down the storm drain I take it out and put it on my plants.”

How to Decrease Road Salt Usage

While eliminating road salt might not be possible while working to stay safe this winter, being mindful of climate-friendly practices can protect the environment for the future.  

For instance, when using road salt, 12 ounces is enough to cover a 20-foot-long driveway or approximately 10 sidewalk squares. 

If the snow melts and salt is still visible, too much has been applied, putting landscape plants at risk.

In addition, residents can use alternatives to sodium chloride such as calcium chloride, which is less harmful to landscapes. If salt must be used, mixing it with sawdust or sand can help dilute it and reduce the amount applied in an area. This intentional reduction in usage is integral to plant health and water quality, as only one teaspoon of salt can pollute five gallons of water.

To decrease the amount of road salt used in the city, the D.C. Snow Team applies a beet juice and brine mixture ahead of snowfall. The beet juice allows the brine to stick to the road, making ice removal easier after a storm, resulting in minimal salt waste. 

“The way it’s mixed and applied ends up being about a 20 to 25% reduction in salt compared to a granular application,” said coordinator for the Chesapeake Bay Landscape Professional Program Jason Swope during a Wisconsin Salt Wise presentation. “It makes removal easier and will also help us decrease the amount of ice melters that we need… for that final cleanup.”

To reduce chloride’s harmful effects on the environment and human health, the Center for Watershed Protection (CWP) is developing a “Smart Salting” training program, with materials including anti-icing, pre-wetting, application rates and equipment handling. This program covers effective application strategies, equipment calibration and deicer storage practices. 

“Currently, there are no regulations on salt,” said CWP water resource engineer Allison Lee to Wisconsin Salt Wise’s audience members, “so developing a ‘Smart Salting’ training for winter maintenance staff is a proactive effort.”