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Road Salt and Fresh Water

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Salt Snapshot Map

Since January 2025, Stroud Water Research Center has been coordinating salt snapshots with dozens of organizations in a multistate effort to sample streams and tell the story of road salt pollution. These findings highlight salt concentrations across various sites, providing valuable insights into the scope of salt pollution and guiding future action.

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Road Salt Is Polluting Fresh Water

Salt keeps us safe on icy roads — but it’s also quietly harming waterways. Every winter, millions of tons of salt are spread on roads, sidewalks, and driveways to combat snow and ice.

While it’s effective at reducing slippery conditions, the consequences for freshwater ecosystems, infrastructure, and drinking water are profound, especially as winter salt use has risen dramatically over the past 50 years.

A graph showing how the use of winter salt for deicing more than doubled between 1940 and 2023.
Figure 1. Metric tons of deicing salt used in the U.S. from 1940 to 2023. Data up to 1975 from U.S. Dept. of Interior, Bureau of Mines; 1975 to present from USGS.
Graph showing rising chloride levels in streams due to winter salt use across different land use types.
Figure 2. The rise in salt use is strongly correlated with urbanization.

Why Is Winter Salt an Issue?

The Impact on Freshwater Ecosystems
Dorothea mayfly photo by David H. Funk.

Winter salt runoff harms aquatic life, turning sections of some streams as salty as the ocean (see Figure 3). When salt levels rise in freshwater ecosystems, sensitive species, like mayflies and amphibians, can disappear. Even the chloride levels recommended by the U.S. Environmental Protection Agency (EPA) may not be enough to protect these vital species.

Graph showing chloride concentration in Shoemaker Creek Pennsylvania, compared to chloride concentration in seawater.
Figure 3. Chloride concentration in Shoemaker Creek, Pennsylvania, during winter storms compared to seawater. Data courtesy of Tookany-Tacony/Frankford Watershed Partnership.
Salt and Drinking Water
A glass of drinking water.

Salt also infiltrates groundwater and rivers, which supply most drinking water. Once contaminated, it’s costly and difficult to remove.

Water treatment facilities struggle to filter out salt, and advanced systems like reverse osmosis are expensive to install and maintain.

Protecting shared water sources is critical for both the environment and public health.

How Bad Is It? Rising Salt Levels in Fresh Water

Since 2016, Stroud Water Research Center has led efforts to monitor salt contamination, collaborating with hundreds of community scientists and volunteers. By measuring chloride and specific conductivity — key indicators of salt pollution — the Stroud Center and partners such as the Tookany-Tacony/Frankford Watershed Partnership have documented alarming levels of contamination in streams like Shoemaker Creek, Pennsylvania, which often exceed EPA safety thresholds (see Figure 4).

Graph showing chloride concentration in Shoemaker Creek, Pennsylvania, in early 2022 far exceeding EPA criteria.
Figure 4. Chloride concentration in Shoemaker Creek, Pennsylvania, as shown in Figure 3, is expanded and compared with the U.S. EPA’s recommended criteria for freshwater chloride concentrations. Data courtesy of Tookany-Tacony/Frankford Watershed Partnership.

Data collected by community scientists and volunteers indicate an alarming trend: salt concentrations in many, if not most, streams remain elevated year-round — even in summer. Worse yet, research from the Stroud Center shows that salt becomes more toxic to aquatic life as temperatures rise.

These findings highlight the urgent need to address the overuse of winter salt. 

How You Can Help

By implementing best practices and new technologies, we can reduce salt use by 30 to 50 percent.

Five ways you can Cut the Salt.
Reducing salt use doesn’t mean sacrificing safety — it means making smarter choices for roads and waterways. Here are five easy ways to Cut the Salt this winter.
Cut the salt graphic: a snow shovel with the text, shovel or plow first.
Remove snow and ice first. Shovel, sweep, or use a blower to clear surfaces before salting.
Cut the salt graphic: a measuring cup with the text, use only what you need.
Use just enough salt. Check your deicer’s instructions to avoid overuse. After storms, clean up leftover crystals.
Cut the salt graphic: icon of a clock face at the center of a snowflake with the text, be proactive.
Watch the weather and treat walkways before ice forms. Be proactive with each unique storm.
Cut the salt graphic: a snow boot with the text, get some traction.
Use sand, grit, or natural materials to improve traction without polluting water. Wear snow boots or ice cleats to stay safe.
Cut the Salt: Educate Yourself and Others.
Talk to neighbors and local contractors about reducing salt use. Small changes by many people can make a big difference.

Take Action

Want to make a difference? Spread the word to help protect fresh water from salt contamination.

The “5 Ways to Cut the Salt” message is available in several formats for individuals and organizations to share with HOAs, local businesses, social networks, and more. Thanks for helping the Stroud Center spread the word!

Social Media Post (PNG)
Cut the Salt Flyer (PDF)
Cut the Salt Flyer (JPG)

Want to do more? Learn how Carol Armstrong, Ph.D., a community science volunteer, reached out to local businesses and local and state agencies to address documented cases of improperly stored road salt, which can pollute nearby streams. She also convinced her township to start an environmental advisory council, offering to share what she’s learned.

Screenshot of Winter Salt Stream Snapshot data map.

Learn About Salt Snapshots

2025 Winter Salt Snapshot: In a January 2025 multistate effort to raise awareness about the harms of road salt, Stroud Water Research Center helped dozens of organizations in the mid-Atlantic region sample streams and tell the story of road salt in their communities. These findings highlight salt concentrations across various sites, providing valuable insights into the scope of salt pollution and guiding future action. Learn more in “Winter Salt Week Unites Those Concerned About Fresh Water.”

2025 Fall Salt Snapshot: In October 2025, Stroud Water Research Center partnered with nearly 100 organizations across the mid-Atlantic to sample streams during baseflow and reveal how road salt pollution persists year-round. The results show that salt persists and accumulates. Learn more in “Beyond the Snow.“

2026 Winter Salt Snapshot: Data is available on the Salt Snapshot Map. A wrap-up event is coming soon; visit the Events page or subscribe to freshwater e-news for updates.

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Winter salt events will be listed here as they are scheduled.

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Road Salt News

Publication title with image of a mayfly
Road salt impacts on soil properties and permanent nitrogen removal capacity of freshwater urban wetlands
Rahman, M.M., M. Peipoch, J. Kan, E. Moore, M. Sena, M. Kantak, S. Sharma, C. Lekha, and S.P. Inamdar. 2026. Wetlands 46, 14.
Publication title with image of a mayfly
Freshwater salinization syndrome is degrading streamwater quality in the National Capital Region national parks, USA
Myers, D.T., D. Oviedo-Vargas, S. Ensign, M. Daniels, J.P. Schmit, M. Peipoch, and J. Kan. 2025. Freshwater Science 54(1): 18–30.
2025 Fall Salt Snapshot data map screenshot
What the Fall Salt Snapshot Revealed About Our Groundwater
Most stream sites sampled this fall exceeded at least one environmental chloride guideline — months after the last road salt was applied.
Stroud Water Research Center is an 2025 Anthem Awards Bronze Winner for the Cut the Salt campaign.
“Cut the Salt” Campaign Wins Anthem Award for Social Impact
The award is a testament to Stroud Center staff who help bring science and outreach to life, and would not be possible without our community of partners, volunteers, and donors.
A bridge is reflected in Aquashicola Creek.
Beyond the Snow
The Fall Salt Snapshot asked a simple question with big stakes: what can we learn about road salt pollution long after the snow is gone?
New Croton Reservoir from Gate House Bridge
Salt Rising in N.Y.C. Source Water, New Report Echoes Stroud Center Study
Twenty-five years after Stroud Center scientists found high salt levels, a new report shows N.Y.C. water sources are trending toward undrinkable.

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