Baltimore Harbor Waterkeeper Alice Volpitta tests water quality in the Jones Falls.

Baltimore Harbor Waterkeeper Alice Volpitta tests water quality in the Jones Falls. / NPR

Would Olympians be able to swim in the River Seine without getting sick?

That’s been one of the big questions at the Paris Games.

But the problem isn’t unique to the French capital. In the U.S., Baltimore is also trying to clean up its waterways for recreation.

Like Paris, the Maryland city is spending billions to update its sewer system. The aim is to stop human waste from spilling into the streams that lead to the Inner Harbor.

Baltimore was forced into action by a 2002 federal consent decree. This summer, over two decades later, residents were finally able to dive in.

Like his Paris counterpart would do weeks later, Baltimore Mayor Brandon Scott was among those taking the plunge.

So too did Adam Lindquist, vice president of the Waterfront Partnership. The group promotes business and tourism around the harbor and organized the swim.

“It was just such an amazing day. There were hundreds of people lining these piers,” Lindquist said, smiling as he remembered the day. “I think some of them were friends and relatives. Some were there for the spectacle because there was a lot of skepticism.”

The Waterfront Partnership tests the water every weekday during the recreation season — from Memorial Day to Labor Day — and posts the results online. The group focuses mainly on the level of bacteria that could make swimmers sick.

“We knew that if it hadn't rained, that it was very, very unlikely that we would have any issues with water quality,” Lindquist said.

Waterfront Partnership vice president Adam Lindquist stands on a dock at Baltimore's Inner Harbor.

Waterfront Partnership vice president Adam Lindquist stands on a dock at Baltimore's Inner Harbor. / NPR

They proved to be right, with levels good enough to allow the swim to go ahead.

The partnership got luckier than their neighbors in Washington, D.C. An event planned for the Anacostia River was postponed three times due to high bacteria levels.

It doesn’t mean that the Inner Harbor is always safe for swimming. Lindquist says it’s fine about 80% of the time.

When NPR visited, samples taken from the harbor showed levels of fecal bacteria to be well within Maryland’s recommended limits.

Allison Blood, the Waterfront Partnership’s staff scientist, also tested the water’s clarity by dunking a black-and-white disc on the end of a rope into the water.

It disappeared from view in less than a meter.

Blood called that result “maybe a little less than average.” Noting the storms the weekend before, she said it looked “as expected.”

Allison Blood, staff scientist at the Waterfront Partnership, takes a water sample from Baltimore's harbor.

Allison Blood, staff scientist at the Waterfront Partnership, takes a water sample from Baltimore's harbor. / NPR

The enemy of safe swimming

It’s after heavy rain that scientists in Baltimore see the worst results in their tests.

“The storm water and sewer infrastructure is old in most cities and not built for the development that has happened,” Blood said.

That’s when the sewer will overflow into the streams that lead to the Harbor, carrying dangerous bacteria.

All the rain also washes animal waste into those streams, which is something else Blood said needs to be addressed.

“How can we implement green infrastructure projects to really filter out that stormwater before it just goes straight, unfiltered into our streams and rivers and harbor?” she asked.

Upstream, a mystery spill spelled trouble

That problem was on display just hours earlier, around two miles upstream from the harbor.

Alice Volpitta, the Baltimore Harbor Waterkeeper, stood next to the Jones Falls where it disappears underground, remaining out of sight until it gets to the Inner Harbor.

This stretch of the stream is a far cry from the picturesque views there — passing under graffitied railway bridges, with trash everywhere.

An empty packet of chips floated down from above like confetti.

The Jones Falls stream disappears underground here, running beneath Baltimore until emerging at the Inner Harbor.

The Jones Falls stream disappears underground here, running beneath Baltimore until emerging at the Inner Harbor. / NPR

Volpitta works for Blue Water Baltimore, an advocacy group. She described her role as “sort of like a water watchdog.”

“My role is to speak on behalf of our local waterways, which is a big job because she's angry a lot of the time,” she added.

That was true on this day. As she tested the water along with her colleague Sarah Holter, the environmental biologist took measurements that she described as “a signature of stormwater runoff.”

It’s not only the rain that’s a problem, according to Volpitta. So is illegal dumping in the stream.

As she spoke, the Jones Falls suddenly darkened — a murky plume appearing in the water. Less than 100 feet away, a dark brown liquid spilled down a concrete bank.

Holter ran off to collect a sample.

Volpitta didn’t believe it to be sewage, and Holter’s sample didn’t smell like it.

Sarah Holter of Blue Water Baltimore holds a sample of polluted water seen running into the Jones Falls in Baltimore.

Sarah Holter of Blue Water Baltimore holds a sample of polluted water seen running into the Jones Falls in Baltimore. / NPR

But it was filled with sediment, which can carry toxic chemicals and heavy metals. The amount of sediment was over 80 times the amount required to report the spill to the city’s Department of Public Works.

Spills like this make recreation in the water really difficult, Volpitta argued.

“We can make really good, common sense policy around not coming into contact with waterways in an urban ecosystem after a certain amount of rain. That makes sense because there's less of a likelihood of sewage contamination,” she said. “But how is anybody ever supposed to know when something like that is about to happen? They can't.”

Beyond swimming

The problems with the sewer, stormwater and pollution go beyond swimming. It’s also about the overall health of the ecosystem.

Blue Water Baltimore looks at more than the amount of bacteria in the water. They also check how much nitrogen, phosphorus and oxygen it contains, as well as other measures of the health of the waterways.

The results are posted on a mapon the group’s website.

The nonprofit’s 2023 report gave much of the watershed a failing grade, including in the Inner Harbor.

A sign above the Jones Falls in Baltimore warns people not to touch the water or debris.

A sign above the Jones Falls in Baltimore warns people not to touch the water or debris. / NPR

In a statement to NPR, the Baltimore Mayor’s Office admitted there’s more to do to fix the problem.

“Certainly our work is not done, but we have made incredible progress on cleaning up the Inner Harbor,” the statement read.

“Numerous systemic improvements to our water and wastewater treatment facilities have improved their operations and improved the health of the Chesapeake Bay overall,” the statement continued.

The statement ended with a pledge to continue to improve the city’s water systems.

That’s something both Lindquist and Volpitta asked for.

If they can all work together, along with the people of Baltimore, there could be more chances for residents to dive into the harbor and channel their inner Michael Phelps or Katie Ledecky.

Obed Manuel edited the digital version of this story.