By Seren Nurgun, Staff Writer for Save The Water™ | December 13, 2015

Road Salt in the Winter

Every winter, communities brace for freezing temperatures, snow, and ice that make road travel dangerous. Without quick and reliable transportation, local economies stall and residents are forced indoors. To fight back, cities rely heavily on sodium chloride—the same salt we sprinkle on food.

Salt works by lowering the freezing point of water. As Scientific American explains: “When added to ice, salt first dissolves in the film of liquid water that is always present on the surface, thereby lowering its freezing point below the ice’s temperature.” 6 This process accelerates melting, helping cars return to the roads quickly.

According to the American Highway Users Alliance, road salt “pays for itself within 25 minutes of being applied, reducing crashes by up to 88 percent, injuries by up to 85 percent, and accident costs by up to 85 percent.” 1

Because it’s cheap and effective, U.S. cities spread over 22 million tons of salt each year. But all of that salt eventually washes into streams, rivers, lakes, and groundwater. 8

Road Salt and Chloride Contamination

A USGS study of 168 monitoring locations found chloride levels exceeded EPA water-quality criteria at 55% of northern sites during winter months. Only 16% of sites exceeded chronic limits during warmer months. 3

Excess chloride harms ecosystems:

• Inhibits plant growth
• Reduces reproduction in aquatic life
• Lowers biodiversity in streams 5

Birds are especially vulnerable, since they ingest salt crystals directly. Other wildlife can suffer when drinking water exceeds 600 mg/L of chloride. 7

Humans aren’t immune either. Sodium from runoff can infiltrate groundwater supplies. The EPA sets a drinking water advisory limit of 20 mg/L sodium—above which water systems must report concentrations to local health authorities. 6 For individuals on sodium-restricted diets, this is especially concerning since excess sodium contributes to hypertension, a risk factor for heart disease, kidney damage, and stroke.

👉 Related: Hold the Salt: The Future of Desalination Technology

Alternatives to Road Salt

Some communities are pioneering creative, eco-friendly approaches:

• Cheese brine (Polk County, WI): Mixing brine with road salt reduces “bounce,” cutting salt use by 30% while saving money and lowering chloride pollution. 2
• Beet juice (Des Plaines, IL): Pre-wetting roads with a beet juice + calcium chloride mix prevents snow and ice from bonding to pavement, reducing salt use. 2
• Molasses blends: Experiments with sugarcane molasses, calcium chloride, and salt have shown promise. 4

Although these require additional research and investment, the benefits are clear: fewer ecosystem damages, healthier drinking water, and substantial cost savings.

👉 More here: Alternate Options for Road Salt Use

References

1. Balakrishnan, Anita. Road Salt: Winter’s $2.3 Billion Game Changer. NBC News, Feb. 19, 2015. Link
2. Copeland, Larry. Communities Seek a Substitute for Road Salt. USA Today, Feb. 23, 2013. Link
3. Corsi, S.R. et al. A Fresh Look at Road Salt: Aquatic Toxicity and Water-Quality Impacts. Environ. Sci. Technol. 44.19 (2010): 7376–82. PDF
4. Long, Emily. More (Or Less) Road Salt. Conservation Law Foundation, Jan. 25, 2011.
5. Mullaney, J. & Noserale, D. Chloride Found at Levels That Can Harm Aquatic Life. USGS, Sept. 16, 2009. Link
6. Pelton, Arthur. Why Do We Put Salt on Icy Sidewalks? Scientific American, Dec. 26, 2005. Link
7. Siegel, Lori. Hazard Identification for Human and Ecological Effects of Sodium Chloride Road Salt. State of New Hampshire, 2007. PDF
8. Stromberg, Joseph. What Happens to All the Salt We Dump On the Roads? Smithsonian, Jan. 6, 2014. Link

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