All these sources contribute to what environmental scientists refer to as a “freshwater salinization syndrome” that is damaging local waterways, harming wildlife and affecting the quality of drinking water throughout the United States — posing risks to people who are sensitive to the two elements in salt: sodium and chloride.
While drinking water quality remains safe for most people now, the compounding effects of a mineral that has been so central to daily life are accelerating and may become irreversible, researchers say.
That’s particularly so in urban areas like metropolitan D.C., studies on the problem show.
Water utilities, warily monitoring the problem, say they may need to invest several hundred million dollars in new desalinization plants to reverse the trend.
“Salt is probably the most serious problem in world history related to water,” said Sujay Kaushal, a University of Maryland biogeochemist, adding that the damaging effects on streams and aquatic life are early red flags to a predicament that could eventually consume the region.
He compared the cumulative effects on the region’s watersheds to the hardening arteries of someone with a high-salt diet.
“Eventually, we know, in the human body, that when you harden the arteries, you create hypertension and all these health problems,” Kaushal said. “It’s the same in the environment. You start crossing these thresholds where you see all these environmental impacts.”
Soap bubbles gathered on the surface of the orange-and-black tinted water flowing from a storm drain pipe into Campus Creek behind the University of Maryland’s College Park campus.
“You see how the water changes color there?” Kaushal asked, pointing to an orange plume.
The colors came from iron and manganese, among the metals that have been entering streams from the pipes and soil with more frequency in recent years — an effect of salt corrosion. And the bubbles, entering through an apparent sewer line leak, were from sodium-containing laundry or dishwasher detergent — a major contributor to the region’s salt problem.
Kaushal passed a feathery thicket of invasive salt-resistant reeds and hiked down to the eroded stream bank as a crew of students who’ve been measuring salinity in streams across the region prepared to test for electrical conductivity, a gauge of how many charged salt ions are in the water.
Some days, when it’s dry, the tests show conductivity comparable to Gatorade, 450 milligrams of sodium per liter. On others, it climbs to the level of a cup of instant ramen, 1,820 milligrams of sodium per liter.
Kaushal, 47, has been sounding alarms about the rising concentrations of salt in the water for nearly 20 years.
His research papers have shown higher levels of salt in streams in urban areas, where roads and parking lots act as funnels for storm runoff into streams.
The studies have shown how human waste is also an increasing contributor. The sodium and chloride it contains passes through water treatment plants — along with the salts in water softeners, lawn-care products and detergents.
And they’ve detailed how salt ions strip away metals inside those pipes and in stream soils, creating “chemical cocktails” that — along with the salt itself — can kill plant life, insects and stream invertebrates, driving away the fish that consume them.
Last September, Kaushal and his team produced another paper finding that freshwater salinization syndrome has begun to undermine the effectiveness of multimillion-dollar stream restoration projects to reduce the flow of pollutants entering the Chesapeake Bay.
With finding after finding, Kaushal has been like a protagonist in an ecological disaster film, unable to get enough people to listen while the signs of a looming crisis surface everywhere, including in his own Chevy Chase neighborhood in 2015, when brownish manganese-enriched water started flowing.
The invasion of salt on freshwater sources “has led to ancient civilizations collapsing,” he said, citing the downfall of Mesopotamia nearly 4,000 years ago. “It affects our food, our drinking water, our air, even.”
Once algae-pocked emblems of water pollution during the early 1970s, the Potomac River and the Occoquan Reservoir — the two sources of drinking water used by Fairfax Water to serve more than 2 million customers in Northern Virginia — are now trending in the wrong direction on salt, while the other contaminants have largely been cleaned up.
The concentrations of sodium in Potomac water drawn in Loudoun County have crept up from about 10 milligrams per liter in 1996 to nearly 16 milligrams per liter this year, with occasional spikes above the Environmental Protection Agency’s advisory level of 20 milligrams for people with high blood pressure.
In the reservoir, sodium concentrations are now consistently above that threshold and, on some days, above the 60 milligrams per liter mark the EPA says is the high threshold at which some people notice a taste difference in the water, according to Virginia Tech’s Occoquan Watershed Monitoring Laboratory.
Concentrations of chloride — which can be toxic to aquatic life and, in high doses, cause high blood pressure and kidney problems in humans — have also trended upward in both waterways.
The EPA does not have standards regulating sodium in drinking water or streams. For aquatic life, the federal water quality standard for consistent levels of chloride is 230 milligrams per liter.
So far, none of the region’s drinking water sources have exceeded that level, though area streams and rivers often show amounts that are far higher when road salt is used during the winter, researchers say.
The trends may be “the canary in the coal mine” indicating the approach of a more worrisome “tipping point,” said Stanley Grant, director of the Occoquan Watershed Monitoring Laboratory.
Beyond that irreversible mark “is a really bad point to start planning,” said Grant, whose lab has been studying pollution in the reservoir for 50 years.
“It’s not that the sodium levels, for example, that are currently in the reservoir are particularly problematic,” Grant said. “It’s the fact that you see that trend upward.”
For the most part, efforts to raise public awareness have focused on reducing the amount of salt-based de-icers used on roads during cold weather, a step already taken by public works departments responsible for road upkeep.
Area officials are also urging neighborhood associations and businesses — who are wary about being sued if someone slips on ice on their property — to use salt judiciously.
Fairfax County issues corrective action notices, with as much as $32,500 in penalties if the recipient is a repeat offender. Since that effort began in 2019, the county has doled out 52 such notices, though nobody has been fined, county officials said.
“We’re putting down a little too much because we’re being overcautious,” said Martin Hurd, a Fairfax County environmental protection specialist. “People don’t really make the connection that it has these downstream effects.”
Residents gathered at a recent Prince William County Board meeting, eager to share their anger over plans to convert farmland in the Gainesville area into 2,100 acres of computer data centers.
Most of them live in Heritage Hunt, a 1,863-home neighborhood near the site that was also once farmland and is now a significant contributor of salt to the Occoquan watershed.
They and environmental groups have seized on the argument that new data centers — and roads and parking lots — would have devastating impacts to the watershed by adding urban runoff to the slice of protected agricultural land known as the “Rural Crescent.”
Many data centers also use water to keep their machines cool, producing sodium-enriched wastewater that flows into sewers, though the industry has been shifting toward more eco-friendly cooling systems.
“Why jeopardize the environmental balance it provides to the watershed of Northern Virginia?” Chuck Zumbaugh, one resident, told the county board at the meeting.