Study finds the Potomac is getting saltier, threatening drinking water and wildlife

It's not just the Potomac. Rivers across the country are getting saltier, too. 


This time of year, pavement is likely to look more gray than black, covered in salt to fend off winter weather and keep roads passable.

Ever wonder where all that salt ends up?

Much of it is ending up in our rivers, making them dangerously saltier. World Wildlife Fund’s quirky #LessSalty campaign illustrates the path of salt from our roads to our rivers.


Scientists analyzed 50 years worth of data from over 230 waterways across the country, including the Potomac. They found that 37 percent of those waters are getting saltier.

In our area, polluted runoff that carries road salt into rivers and streams is largely to blame. Despite receiving only 3 inches of snow this season, crews in the District have laid down over 15 tons of rock salt and 290,000 gallons of salt brine. And that's just this year.

As Jacob Fenston reports from WAMU, all that salt has made tap water sourced from the Potomac three times saltier than it was 25 years ago. With over 5 million people relying on the Potomac for drinking water, that's a serious public health problem.

Salt is hard for water treatment facilities to remove, and it can cause serious damage to pipes. The salty water from the Flint River is what led to the lead pipe corrosion that caused Flint’s recent drinking water crisis.

Saltier waters also pose an issue for local wildlife. Freshwater fish and underwater plants simply cannot survive in salt water. 

Not all rivers are getting saltier though. The study found a decrease in salt concentrations in waters in the Southwest, where regulations to control salt pollution are already in place.

Local transportation officials have started taking steps to reduce salt in recent years. Maryland's Highway Administration, for example, has reduced its salt use by 58 percent since 2015. But to properly address the issue of salt pollution, the study's author argues that we need stronger clean water protections, both locally and federally.

“The Environmental Protection Agency does not regulate salts as primary contaminants in drinking water at the federal level, and there is inconsistency in managing salt pollution at the local level. These factors are something communities need to address to provide safe water now and for future generations,” study co-author Sujay Kaushal said in a press release.


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