The Washington region is growing — a metropolis of nearly 6 million people where area officials are pressing to build another 320,000 homes by the end of this decade.
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 Board of County Supervisors 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.
The proposal is part of an ongoing assessment of the overall land use plan in Virginia’s second-largest county as it seeks to accommodate more growth and, in the process, become a major economic hub in the Washington region. The $8.4 billion data center industry is one route to that goal, considered easy money as far as tax revenue goes, given that the mammoth structures require few county services and the 33 data centers already in the county contribute $79 million to the annual budget.
Fairfax Water has been monitoring those discussions, sending a letter to the county in May that urged officials to incorporate “a rigorous evaluation of the potential impacts” to the Occoquan watershed.
It’s part of an evolving watchdog role the water utility has taken on as the rural buffer zone around the reservoir — itself lined by homes with commanding views of the water — steadily disappears.
The rapid growth of the tech industry in the region factors into that role more frequently.
In 2019, Fairfax Water saw a surge in sodium entering the reservoir from one source: Micron Technologies, a global computer chip manufacturer whose $3 billion expansion of its plant in Manassas is expected to generate 1,100 high-skilled jobs by 2030.
Micron, which uses sodium while washing its chips, discharges 2.3 million gallons of wastewater per day, accounting for 14 percent of the sodium in the treated water entering the reservoir. As part of the expansion, Micron plans to increase that amount by 70 percent.
Fairfax Water discovered that the concentrations of sodium in Micron’s output had also jumped, to 140 milligrams per liter from 100 milligrams per liter, which itself was nearly 40 percent higher than years before.
The tech company initially ignored the utility’s requests to reduce its sodium discharge, angering Fairfax Water board members and employees, according to a recording of a 2019 board meeting.
“Our customers are going to taste this if we don’t do something now,” a Fairfax Water employee told the board during the meeting.
After some back and forth — including a complicated proposal to allow Micron to continue at the higher levels during rainier weather — the company agreed to return to 100 milligrams per liter. That took effect in October, a Micron spokeswoman said.
Though resolved, the episode illustrates the various economic pressures now placed on drinking water sources in the region, said Phil Allin, chair of Fairfax Water’s board.
“It’s a valuable resource and it’s something that we can’t screw up,” he said about the reservoir.
But the demand for more development is pressing.
And it’s not just new industry. Like the rest of the Washington region, Prince William is trying to cultivate more affordable housing. A shift toward larger suburban homes with more space prompted by the coronavirus drove up prices in an already expensive housing market. In the spring, inflation further drove up prices, leaving many homes out of reach to thousands of lower-to-middle-income families.
Several supervisors on Prince William’s Democratic controlled board see the 117,000-acre Rural Crescent as a logical place to put some new homes and businesses — including, possibly, data centers — after other, more densely populated areas of Prince William have been built out.
“At the end of the day, we’re going to build more homes, and I’m pretty sure it’s going to create these salt runoffs,” Supervisor Victor S. Angry (D-Neabsco) said near the end of the meeting.
“On the other hand, I have folks who deserve a slice of their paradise, their own home, in these locations,” he said. “And we’re going to do that. It’s a tough decision.”
Bulldozers rumbled at the construction site of a development in Fairfax City that, along with 50 townhouses, will feature a 200-unit senior living facility, part of a separate demand for housing as the region’s elderly population continues to grow.
About 50 yards away, an eroding sliver of Accotink Creek was covered by algae blooms and other signs of urban runoff as a few tiny minnows darted past where a culvert will cover the stream as part of the development.
The creek and its surrounding Accotink watershed, which has lost a significant portion of the insects and invertebrates that are fundamental to healthy waterways, is the only one in the Washington region that is being regulated for particles found in winter salt, specifically chloride.
The success of that effort — which focuses on best practices for handling road salt, in part through requirements linked to storm sewer system permits — could be a guide for future regulation of streams.
Researchers argue that the need for more regulation is becoming urgent, though they acknowledge that it could be costly for local agencies and complicated in urban areas that have competing needs surrounding economic development and social equity.
“It’s a wicked problem, man, because you’ve got all these different factors coming into play,” said Grant, whose lab is embarking on federally funded research that, in part, will look at how much sodium in drinking water people can live with — data that will inform discussions on ways to change consumer behavior with respect to salt.
More research is needed to better determine how much of an impact the salt is having, said Will Isenberg, a specialist focusing on watershed and ecology issues at the Virginia Department of Environmental Quality (DEQ).
“Something that we and other states have been requesting of the EPA is to raise the priority of freshwater salinization so that we can have that kind of information,” he said. “If it’s determined that a water quality standard is necessary for whatever ion, then we can weave that into our regulatory programs.”
An EPA spokesperson said the agency is in the process of updating its aquatic life criteria for chloride, informed by the latest research on salt ions.
With the Accotink, Virginia’s DEQ decided to create a “total maximum daily load,” or TMDL, limit for chloride after a federal judge ruled in a 2012 lawsuit against an EPA effort to regulate for the flow of urban runoff damaging streams.
Fairfax County and the Virginia Department of Transportation — who both sued the EPA over the issue — argued it would be unreasonably expensive and impractical to try to control the flow of storm water.
After years of study and community dialogues over the chloride TMDL, it is just beginning to be implemented, DEQ officials said.
Chloride levels in the creek range from minimal amounts at some sites to as many as 2,500 milligrams per liter in others, according to data provided by DEQ.
Whether a TMDL for chloride or any other salt ion will be created for other streams with rising salinity depends on how well those bottom-dwelling insects, worms and mollusks fare, which could take several years to know, environmental officials and groups addressing the problem say.
“It’s a problem that has been a long time in the making, so it’s going to take a long time to turn around,” said Steven Bieber, who oversees the water quality program at Metropolitan Washington Council of Governments. “And a lot of effort to turn it around.”
In the meantime, the signs of mounting stress to stream life continue.
Katy Johnson recalled how, in the portion of the creek behind her Fairfax City home, the song of Cope’s Gray Tree Frogs — dependent on aquatic life in the stream — once filled the night every summer.
The frogs, sensitive to salt, are gone now, said Johnson, a volunteer with the Friends of Accotink Creek restoration group.
“I really miss those frogs,” she said.