When Potomac Riverkeeper Dean Naujoks speaks to groups about his work, he often fields a question that, until now, he hasn’t been able to answer: “Is it safe to go in the river?”
“I’ve been very uncomfortable answering that question because we never had data,” Naujoks said, looking out across the Potomac from a dock at Maryland’s National Harbor. “This area had almost zero bacterial monitoring.”
Now, that’s beginning to change.
As of this summer, the Potomac Riverkeeper Network and Anacostia Riverkeeper have each launched sizable citizen monitoring programs — one of them buoyed by a mobile, boat-based lab — focused on determining whether bacteria that can be harmful to human health are present in the rivers.
When the weather is nice, hundreds of people plunge their paddles, toes — or their entire bodies — into these waters, which run through the region’s most populous areas in and around the District of Columbia. Paddleboarders are easy to spot balancing on the ripples near Georgetown’s waterfront, and experienced swimmers dive headlong into the main branch of the Potomac at National Harbor during twice-weekly open-water swims.
Each year after wet weather, though, these same Potomac waters receive millions of gallons of sewage and stormwater from wastewater treatment plants in the District and Alexandria, VA.
Those systems are being updated to curtail polluted overflows, which contain human waste and often high levels of fecal coliform and other bacteria. Some of those bacteria can cause stomach flu-like symptoms or severe infections, yet few people are aware of the risk. And you don’t have to swallow the water to be affected; bacteria can enter the body through the ear canal and small cuts or scrapes.
Riverkeepers for the Anacostia and Potomac are in a tight spot as they work toward a goal to make these waters “swimmable and fishable” in the next decade — encouraging people to connect with the rivers, but recognizing that water quality is not always safe for recreation. Monitoring, they say, can help residents know when it’s safe for water contact and when it is not.
“We want people to enjoy the waterways when it’s safe to use them, and we want it to be increasingly safe,” said Nancy Stoner, president of the Potomac Riverkeeper Network, “We also want people to know when it’s unsafe — so they won’t go in and also so they’ll push for investments.”
It is illegal to swim in District waters, a law the network would like to see replaced with water contact recommendations linked to monitoring. But recreating on vessels such as stand-up paddleboards is permitted — even though balancing on the boards often involves falling in. Swimming is permitted during special events if the water passes a half-dozen quality tests in the weeks leading up to an event. But rains and high bacteria levels have foiled the swim portion of the Nation’s Triathlon more often than not the last six years.
In Maryland and Virginia, the Potomac is more often used by boaters than swimmers, but high school and college rowing crews wade in to push their vessels, and swimming is popular at a handful of locations relatively close to polluted overflows. No organized swims take place in the Anacostia, but some groups have floated the idea of suspending a swimming pool filled with clean water in the river — to ease people into the idea of future safe swimming.
The Anacostia Watershed Society gave the Anacostia its first passing grade, a D-, in 2018 in a report that stated sewage overflow improvements would help the river become ready for swimming by 2025. Bacterial monitoring for recreation began in the Anacostia, Rock Creek and District portions of the Potomac that same year under a grant from the District Department of the Environment. The effort should provide a baseline of how often the river’s water in and around the District is swimmable now, while tracking progress toward future goals.
Citizen monitoring trainings in the District were so popular this year that organizers added an additional session this month, "and we have even more demand," said Robbie O'Donnell, project coordinator and resilience lead for the Anacostia Riverkeeper.
Naujoks is glad to see the monitoring spread farther downriver as more funders have seen the value of recreational information. His 14-year-old daughter used to swim often in the Potomac near Alexandria’s Belle Haven Marina a mile away from their home — before he found out a couple of years ago that sewage from the city’s treatment plant habitually overflowed into Oronoco Bay, just upstream.
“When we first moved in, she was 11. She was just a kid jumping in the river,” he said. “After a rain event, I’d say, ‘Please don’t go in the river,’ but we had no data.”
Now, Belle Haven Marina is one of nearly two-dozen sites along the Potomac and the Anacostia from which volunteers are drawing water samples every Wednesday. By Friday, the results are available in time for people to decide whether it’s safe for a dip. Those results are posted to an online app, Swim Guide, that already covers nearly 8,000 locations around the world.
Anne Irving, an Alexandria resident and member of the Hunting Creek Garden Club, will be one of the volunteers collecting that data. Her club also donated $5,000 from its conservation fund to the nascent monitoring effort.
“We wanted to do it because we live in Alexandria. With all the recent information on the sewer system, this seemed like a good idea,” Irving said.
Irving also had two sons who were on a local high school’s rowing team, which pushes out to the Potomac from Oronoco Bay, where the outfall with the highest volume of polluted overflows also is located.
“They survived, but I didn’t realize it was not monitored at the time,” she said.
On a mid-May morning, Irving was among more than a dozen volunteers gathered at National Harbor to learn how to collect the water samples and deliver them to a yacht-turned-mobile-lab that’s the hub of the Potomac Riverkeeper Network’s monitoring program. A former Navy admiral donated the 42-foot vessel, now named the “Sea Dog,” last fall just as the nonprofit’s new citizen monitoring program was coalescing.
Other grants have since helped to transform it into the region’s first floating laboratory focused on monitoring water conditions for recreation. A stainless-steel table, mini fridge and lab equipment had recently replaced the yacht’s futon mattress when the volunteers were brought on board to see what will happen with their samples.
Annie Bronez, the network’s outreach and volunteer coordinator, had already explained how to take the temperature of the water and the air and measure the water’s pH, a measure of acidity, in the field. Along with those written results, two bottles filled with samples of river water will be placed in a cooler and delivered to this boat within five hours, where they’ll be analyzed for turbidity and bacteria levels.
“This machine is the incubator,” Patrick Fletcher, a volunteer who is also a post-doctoral research fellow at The National Institutes of Health, told volunteers clustered on the boat. It takes about 24 hours to grow a culture and identify bacteria. “E. coli like to be at about 35 degrees Celsius, which is the temperature of the inside of your intestines that we want to mimic,” he said.
He held up the results of a sample from the previous week, with liquid divided among rows of small cubes in a sealed, metallic tray. Several of the cubes glowed a fluorescent green under the black light, indicating the presence of certain bacteria.
“We count how many big squares are glowing and how many littles ones are glowing,” Fletcher said, comparing those numbers to a chart, revealing that the sample from early May would not meet Virginia water quality standards.
A sample taken the week before and a few since have, however, met those standards, which means the project posted a green “meets water quality standards” emblem on the Swim Guide app. When quality falls close to or below those standards, the emblem is yellow or red.
“When the water is turbid like this, that’s when it’s more likely to be high [in bacteria], when it looks murky,” said the Potomac network’s Nancy Stoner. “Over time, we’ll have trend data as well. This year will be the baseline.
In the future, Naujoks would like to create a larger monitoring program around the boat, one that perhaps goes on the road to popular public access points along the Potomac. In New York, he said, a similar, boat-based lab traverses the Hudson River, collecting hundreds of water quality samples from volunteers to be analyzed on board.
“We’d like to make it a port-of-call thing where we go down the river, introducing ourselves and inviting people to see the lab,” Naujoks said, “anything we can do to promote this idea of a swimmable Potomac and to get people to start making connections.”
(As originally posted, this story misidentified one of the groups doing citizen monitoring. The Bay Journal regrets the error.)