Cleaning up the Seine: the Olympics boosts a Parisian dream, but it's still far from fully achieved

PARIS (AP) — The Seine River has been one of the stars of the Olympics — whether as the scene of the ambitious opening ceremony or as the Games' choice for the triathlon and marathon swimming competitions.

The challenges to featuring the famed Paris waterway so prominently were considerable. The work that went into tackling one of the largest — concerns about its water quality — could be the Games' biggest legacy for the river snaking through the French capital and arguably for Paris itself.

Authorities vow that their 1.4 billion-euro ($1.5 billion) cleanup efforts will allow a river that was so polluted Parisians were banned from taking a dip in it for a century to finally open up as a summertime swim spot. They also hope a cleaner river revitalizes the overall environment. Some experts are skeptical, however, and the Olympics have shown there still remain some hurdles ahead.

Results of daily testing during the Games showed the Seine's water was not always in line with acceptable guidelines for illness-causing bacteria such as E. coli. That canceled several test swims and postponed the men’s individual triathlon by a day. Better results later allowed Olympic events to take place.

French President Emmanuel Macron claimed victory following the Olympic triathlon tests, calling it “a fabulous legacy for the Paris region’s residents who will be able to swim in and for biodiversity.”

Bathing spots for all

For many Parisians, swimming in the Seine has been nothing but a dream.

In the 1970s, only three to four fish species were living in the Paris section of the river, with waters deeply polluted from industrial activity. Now, around 35 fish species may need to get used to sharing the Seine.

A swimming test open to the public has been scheduled for mid-September ahead of a city promise that anyone can take a dip starting next summer.

Paris officials have identified three potential bathing spots, one close to Notre Dame Cathedral, another near the Eiffel Tower and a third in eastern Paris.

It is dependent on water quality results falling in line with European rules.

In a warming world, the river could help people stay cool during increasingly frequent heat waves. However, rain storms can wash runoff and wastewater — and, therefore, bacteria — into the river, and climate change is making weather more extreme.

Since 2017, Parisians have been swimming during the summer in the Canal de l’Ourcq, in a northern part of the capital. By contrast with the Seine, water in the Canal de l’Ourcq has been consistently found to be of good quality over the past few years, according to analyses reviewed by the Regional Health Authority.

A challenging cleanup

To get the Seine to a swimmable state, authorities opened new disinfection units and created a huge storage basin meant to prevent as much bacteria-laden wastewater as possible from spilling directly into the Seine when it rains.

Officials also have targeted houseboats that used to empty their sewage directly into the Seine, requiring them to hook up to municipal sewer systems or loose their berth.

Recent efforts are heading in the right direction, yet they're still insufficient to guarantee clean waters, said Michel Riottot, a health and environment expert at the France Nature Environnement group.

That's because when sewage networks become saturated with rainwater — especially during storms — they still discharge surplus into the Seine, he said. Plus, when there is rain upstream in a region known for its grain farming, pesticides accumulate into waterways flowing into the Seine, Riottot added.

Some 23,000 homes upstream of Paris also are emptying their sewage into the rainwater system that flows directly into the river, Riottot said.

For the Olympics, only two indicators were being analyzed for Seine water quality: the fecal bacteria E. coli and enterococci.

“If you can find them at a higher level than legal thresholds, it means there are lots of other things that can sometimes be more dangerous than these two” in the water, Riottot said, such as COVID-19, hepatitis A and chemical pollution.

Ready to dive in

Still, the idea of swimming in the Paris landmark is irresistible to many.

An experienced open water swimmer, Sina Witte got enthusiastic when she and other members of her Parisian swim club were offered the chance to take a dip alongside Paris mayor Anne Hidalgo just before the Olympics.

“I really enjoyed it,” she said this week, spending about 45 minutes swimming down and up the river. She did not get sick afterward.

“I’m not racking my head too much about it — as soon as we can swim around, I’m going, it makes me happy,” Witte said.

She participated in a triathlon competition in the river in 2009, 2010 and 2011 — exceptions to the general ban on swimming there since 1923.

In 2010, participants received a warning that the river didn't comply with water quality requirements. The E. coli levels were 2.5 times higher than required, according to a photo of the document seen by AP.

Witte remembered that thousands of people took part.

Olympics' environmental efforts

Paris City Hall promised that "the whole ecosystem will benefit from this cleanup project.”

François Houix, Olympics project manager at the Voies Navigables de France, the body in charge of managing the country's inland waterways network, said the Olympics helped broader efforts to improve how rivers and streams work.

A floating barrier set up upstream of the Olympic swimming site catches both green and plastic waste and other polluting items in the Seine, he said. The system will be extended after the Games.

State-sponsored benefits also urge boat companies to be greener, including a bonus when boat operators switch to electric engines. There will be about 40 electric boats operating in Paris by the end of the year, up from only one in 2018, Houix said.

The Games also prompted a 15 million-euro investment to reopen a branch of the Seine to boats in the disadvantaged northern suburbs of Paris. That's because a main stream along the Olympic Village was closed for weeks for security reasons.

Local officials say that when boat traffic stops on weekends or later in the day during the summer, it will allow swimming, rowing and stand-up paddleboarding either on that reopened branch or on the main stream, Houix said.