Road salt (sodium chloride) is everywhere during winter months. It keeps us safe on roads and sidewalks, but it can also pose a threat to fish and wildlife as well as human health.
Fish and bugs that live in freshwater streams can't survive in extra salty water. And many of us (more than 118 million Americans) depend on local streams for drinking water. Water treatment plants are not equipped to filter out the extra salt, so it can end up in your tap water and even corrode your pipes.
This past winter, people from around the country tested their streams for salt. The maps at the right show what they found: 31 watersheds tested by citizen scientists always showed normal, safe chloride levels, but high levels of chloride were found in 8 other watersheds that include metropolitan areas.
Repeated testing demonstrated that these metropolitan watersheds had consistently high levels of salt: 25% of test results were above the maximum level of salt considered tolerable for freshwater organisms (230 ppm), and an additional 31% were noticeably higher than levels of salt normally found in freshwater. Of the watersheds that tested high in chloride, the Lower Delaware and the Schuylkill in the Philadelphia metro area, the Middle Potomac-Anacostia in the Washington, DC, metro area, and the Clinton in the Detroit area showed abnormally high salt levels on more than half of their results.
Read more about what was learned from the 2018-2019 Winter Salt Watch season.
Though winter is now over, the danger salt poses to stream life has not passed: summer rainstorms can wash last season's salt out of the ground and into streams, and new research shows that salt is even more harmful to stream life when the water is warm.
You can take action.
- Scout for Salt Piles: If you live in one of the watersheds with high salt levels, or if you noticed salt piles sitting on roadsides last winter, call your city or county department of environmental protection to make sure they are aware of these issues.
- Write a Letter to the Editor: Write in to your local newspaper or other news outlet to educate your community about how road salt harms stream health. You can start with our sample letter and adapt it for your use. (Download the Word file or PDF.)
- Share Best Practices: There's no mystery to limiting road salt usage – it's about following best practices. Share road salt best practices with your community managers and state agencies.
Your efforts make a difference.
This spring, the Philadelphia Inquirer ran a front-page piece in its regional section highlighting Salt Watch results in streams throughout the region. The chloride levels around Philadelphia were especially high, with 23 tests measuring concentrations of 230 ppm or greater. One small stream had a chloride concentration of 800 ppm in March! League staff and local volunteers were interviewed for the story.
League staff were also interviewed by television and radio stations in Philadelphia. Listen to one of the radio interviews.
These media stories helped more people learn how excess road salt can create water quality problems. When more people understand the problems, we can work together to find solutions.
Thank you for keeping our streams safe!