Question of the Week: Road Salt, Snow Melt and the Bay

Welcome to this week’s installment of the BayBlog Question of the Week. Each week we'll take a question submitted through the Chesapeake Bay Program website and answer it here for all to read.

This week’s question comes from Daniel, who came to our website seeking information about the effects of road salt on the Chesapeake Bay and its local waterways. He said, “With all the information that is out there about the pollution in our Bay…it seems like we have created another major source of pollution by throwing all the salt into the Bay.”

Much of the Chesapeake Bay watershed has experienced record-breaking snow storms this winter. With roads covered in snow and ice, road crews had to use the most effective deicer at their disposal: salt, and lots of it. Controversy struck when it was announced that plows in Baltimore would begin dumping snow from the roadways into the Inner Harbor. What would all of that salt do to the water? Isn’t there a better way to handle it?

While public safety was the most important factor during these major snowstorms, the decisions made by public officials also took environmental concerns into consideration.

Dumping snow into the Inner Harbor or the Chesapeake Bay, which are already brackish (a combination of salt and fresh water), is not necessarily bad because salt is already present in the water. However, dumping salt-treated snow into freshwater streams and creeks is dangerous because it can drastically change the amount of salt in the water, harming the freshwater species that call these waterways their home.

Of course, even without dumping snow directly into a body of water, salt will end up there as snow begins to melt and run off our streets, lawns and driveways. Since runoff is the fastest growing source of pollution to the Chesapeake Bay, scientists in the region will closely monitor the effects of snow melt and runoff.

The runoff caused by snow melt, however, is generally more gradual than that of a strong rain storm, giving road salt and other pollutants more time to absorb into the ground, where they can be filtered out by trees and vegetation. Heavy rainfalls, on the other hand, accelerate the speed at which polluted runoff flows into streams, rivers and the Bay.

To get back to the question from Daniel, yes, the salt used on roadways during snowstorms can become a pollutant in the Chesapeake Bay and local rivers, creeks and streams – but so can fertilizers, dirt, oil, trash and other substances carried by runoff into waterways. There are other deicing agents that could be used, but most are more expensive and some have not yet been tested for environmental effects.

Since this year was a rarity in terms of snowfall for most parts of the Chesapeake Bay watershed, hopefully the problem of too much road salt and snow melt won’t be something we’ll have to address very often in the future!

Do you have a question about the Chesapeake Bay? Submit it on our website and it could be our next Question of the Week!