In Late January, Communities Came Together to Measure the Impact of Road Salt on Freshwater Streams, as They Raised Awareness and Took Action
Too Much Salt
Late last month, more than 300 volunteers and about 30 organizations in Pennsylvania and Delaware answered Stroud Water Research Center’s call to gather chloride data from streams for Winter Salt Week, a multistate effort to raise awareness about the threat of road salt to fresh water.
The volunteers collected stream water samples and tested their chloride levels, an indicator of road salt pollution. In addition, over 400 people from eighteen states and five countries accepted the Stroud Center’s Cut the Salt challenge by requesting free Freshwater Test Kits to test their waterways and share their chloride data with scientists and online. Together, the volunteers and Cut the Salt participants contributed to a map of road salt impacts across more than 600 stream sites.
More than 70% of the stream sites exceeded one or more safe limits (see Table 1). The highest chloride reading was 15,900 milligrams per liter, far exceeding even the highest recommendation, which is 860 milligrams per liter during only acute periods.
U.S. and North American Chloride Criteria and Thresholds
| Organization | Long-term (chronic) chloride toxicity criterion (mg/l) | Short-term (acute) chloride toxicity criterion (mg/l) | Links |
|---|---|---|---|
| U.S. Environmental Protection Agency (and many states)(1988) | 230 | 860 | Ambient Water Quality Criteria for Chloride-1988 |
| Canadian Council of Ministers of the Environment (2011) | 120 | 640 | Canadian Water Quality Guidelines for the Protection of Aquatic Life – Chloride |
| Ohio EPA, Macroinvertebrate Hazard Concentration (2021) | 52 | – | Assessing the Impacts of Chloride and Sulfate Ions on Macroinvertebrate Communities in Ohio Streams |
| Maryland Biological Stressor Identification Process, Chloride Threshold Value (2009) | 50 | – | Maryland Biological Stressor Identification Process |
| Natural range in the northeastern U.S. | 5–20 mg/l | ||
Water Quality Speaks to Human Actions on Land
High chloride levels appeared mostly in or near urban and suburban areas. Rural streams, where road salt is likely used less or not at all, had much lower levels.
The results come on the heels of recent storms and snowmelt, when scientists expect salt levels to be higher.
Indeed, elevated levels found during Winter Salt Week point to intensive road salt use, which can damage infrastructure, threaten the health of freshwater ecosystems, degrade drinking water, and lead to year-round contamination of streams, rivers, lakes, and wetlands.
It’s part of a national trend. Road salt use has risen dramatically since the 1940s to more than 48 billion pounds per year, and all that salt is showing up in what should be fresh water — in streams, rivers, lakes, and groundwater.
“Salt is a great example of how pollutants move through a landscape. What we put on our land ends up in our water,” says John Jackson, Ph.D., a freshwater ecologist and an expert on road salt’s impacts on aquatic life.
Raising Awareness
The good news is that using less salt and maintaining road safety is possible. Some states are already doing so. Maryland, for example, has cut its salt use in half.
Amanda Goldsmith is a watershed specialist with the Lancaster County Conservation District, which rallied volunteers to monitor streams for Winter Salt Week. She says, “It was great to see so many new and existing Water Quality Volunteer Coalition members come together. We were pleasantly surprised by some results and concerned about some of them as well. It is an important reminder to monitor salt usage at home and in your community.”
On January 31, the final day of Winter Salt Week, the Stroud Center hosted an event in West Chester, Pennsylvania, in partnership with West Chester University and West Chester Borough. The event brought together researchers, educators, community scientists, West Chester University and Henderson High School students, and the media, who participated in stream sample testing, salt tasting, and more.
Joseph Debes, a community science volunteer and Penn State Master Watershed Steward, was among them. In addition to volunteering to test water samples at West Chester Borough Hall, he engaged two people from his local watershed who tested 10 stream sites.
He says, “I thoroughly enjoyed the experience. I was excited to see the energy that the event generated among the students and our citizen science partners throughout the community! Capturing live results on the big screen was truly amazing, and I definitely know the awareness was raised among the participants.”
Attendees of the event at Borough Hall saw results appear in real time on a big screen display of the online data map. The media featured this and more in Winter Salt Week coverage:
- “Winter Salt Week highlights road salt use in Delaware River Basin,” Delaware Currents.
- “Road Salt Pollution Isn’t Just a Winter Problem Anymore,” Delaware Currents.
- “How Road Salt Affects Local Creeks,” FOX Weather Philly.
- “Road Salt Is Focus Of Data Collection Campaign,” Water Loop.
- Podcast: Conducting World-Leading, Innovative Freshwater Research.
Learn more about road salt and what you can do to protect your water.
