Fresh water is 32 percent saltier than years past | WYPR

Fresh water is 32 percent saltier than years past

Jan 15, 2018

Gwynn Falls stream in northwest Baltimore.
Credit Dominique Maria Bonessi

America’s fresh water is getting saltier, and has been over the last 50 years. That’s according to new research from the University of Maryland.

You’ve seen those big trucks driving around dumping salt on the roads. University of Maryland scientists say that is just one of the reasons that in the continental U.S. freshwater has become 32 percent more salty, and 90 percent more acidic.

But, as Sujay Kaushal, a UMD scientist who’s been studying this phenomenon, explains it’s not just road salt.

“There are many different types of salt in the environment," says Kaushal.

For example, potassium is a salt found in fertilizers. There is also salt found in building materials that can contain calcium carbonate.

All of these types of salt can end up in the drinking water supply.

“Including the Baltimore drinking water supply," says Kaushal.

Kaushal explains how salt can leach into the drinking water.

“There are other salts that can be held onto the bottom of streams or rivers, and when you add a salt," Kaushal says. "This creates a cascade of other salts causing the salt to be released from the soils to the stream.”

From there the water will end up in a treatment plant where chemicals are added to clean the water. This then increases acidity and can corrode pipes.

“Salty water goes through the pipe, it can affect the corrosion of the pipe," Kaushal says. "And then the release of metals from the pipe into the water.”

According to the report, these metals can be toxic, but Kaushal says it’s still unclear what affects that could have on people.

“Salts are not regulated primary contaminates to drinking water by the EPA," says Kaushal. "That’s an issue society is going to have to grapple with these long-term trends and what affects they could have.”

University scientists took samples of water from the Susquehanna River, the Chesapeake Bay’s largest tributary, and found long-term increases in acidity. The report says that this is due to “land development, changes in salt pollution, and/or response to changes in acid rain.”

University of Maryland's research on acidity trends in the Susquehanna River, a major tributary of the Chesapeake Bay.
Credit University of Maryland

In Baltimore City, the Department of Public Work monitors salt and acidity of water, but as DPW spokesperson, Jeff Raymond, wrote in an email, “it is very difficult to regulate the use of road salt when the public demands de-iced, passable roads.”

The city does follow the state’s Salt Management Plan released in October of last year. While the plan lays down policy for maintenance workers, there is no mention of how much salt is too much.

Raymond says the city will continue with its efforts “to educate the public about our drinking water and our efforts to keep it clean.”

On the federal level, Raymond says DPW would expect any “federal regulations to be in the form of a total maximum daily load [TMDL] for chloride.”

Although there are already guidelines in place for how much chloride is permissible in drinking water, according to the EPA.