Will the Seine River Be Clean Enough for Swimming by the Time of the Olympics?

For centuries, the Seine River has inspired artists and provided a picturesque setting for romantic walks near iconic Paris landmarks like the Eiffel Tower and Notre-Dame. However, it's not a swimming-friendly waterway; swimming has been prohibited since 1923 due to river traffic and pollution.

The City of Light is eager to change this narrative. For years, efforts have been underway to clean the Seine, with the aim of showcasing its transformation during the highly anticipated Paris 2024 Summer Olympics.

If successful, the Seine will play a pivotal role in the Games’ opening ceremony, which will, for the first time, occur outside a stadium: a flotilla of boats will carry athletes through the city along this iconic river. Additionally, the Seine will host swimming events, including two long-distance races on August 8 and 9, as well as the swimming segment of the triathlon from July 30 to August 5. Following the Games, the city hopes the river will remain clean enough for both locals and tourists to swim.

However, with less than a month until the Games commence, it seems increasingly unlikely that the river will be clean enough for athletes to swim. A June 21 report from the Paris region and Mayor Anne Hidalgo’s office indicates that recent tests reveal dangerous contamination levels, with E. coli counts exceeding the World Triathlon Federation's maximum threshold by more than ten times, posing risks such as diarrhea, urinary tract infections, pneumonia, and sepsis if ingested.

The report cited heavy rainfall and cool temperatures as contributing factors to the inadequate water quality.

As of this publication, the Olympic organizers have not disclosed whether there is a backup venue. Team USA open-water coach Ron Aitken informed USA Today that he suspects organizers are reluctant to reveal a Plan B due to the excitement surrounding swimming in the Seine.

“I don’t believe the Paris organizers want the public to know about a backup plan because it might lead everyone to think, ‘Forget it. We won’t participate since you have an alternative,’” Aitken explained. “They likely want you to think there’s no fallback, especially if they believe they can manage it safely.”

However, if there isn’t an alternative plan, eliminating the bacteria is crucial for the triathlon and swim marathons to proceed. This task could be complicated if Parisians, frustrated by the strain the Games impose on public transportation, security, and city resources, go ahead with protest plans that involve defecating in the iconic river.

The cleanup of the Seine was a pivotal element of Paris's bid for the 2024 Olympics. While the restoration of the river’s water quality has been expedited by this international sporting event, establishing a clear timeline for enhancing the ecological and environmental state of the Seine and its tributaries has been an ongoing effort for decades. In 1990, for instance, Jacques Chirac (then the mayor of Paris and later president) promised to swim in the river within three years to demonstrate its cleanliness, a promise that never came to fruition.

To meet its goals in time for the Games, Paris is focusing less on purifying the Seine and more on preventing untreated water from entering the river. The city has installed new underground pipes, freshwater tanks, and pumps aimed at keeping harmful bacteria like E. coli and enterococci out. Authorities have upgraded sewage treatment facilities along the river and its tributaries, and have replumbed upstream homes that were previously discharging wastewater into the river. Additionally, the city has developed storage solutions, including a massive basin near Paris’s Austerlitz train station that can hold the equivalent of 20 Olympic swimming pools of contaminated water, which will now be treated instead of being released untreated into the river, according to the Associated Press. This initiative has a budget of $1.53 billion.

By June 2023, it seemed that the mission would be on track. Once home to just three fish species, the Seine now hosts 30 species, a testament to the city’s progress, according to Solene Bures, a spokesperson for the City of Paris. She noted that if the Olympic and Paralympic Games had taken place in the summer of 2022, the water would have been safe for swimming 90 percent of the time.

However, weather conditions were always unpredictable. If a storm occurs in the days leading up to the competition, the resulting runoff could compromise water quality. In such a scenario, Olympic officials would have to delay the races scheduled for the Seine until the water meets quality standards.

In 2025, Paris city officials aim to establish permanent swimming areas at four sites along the river in the city center. (Additional swimming spots may open later at other locations along the Seine, as indicated by the city.) Bures mentioned that it is still too early to determine what these areas will look like.

Although the Olympics are not usually associated with positive environmental outcomes—often resulting in stadiums that remain unused after the games, like Beijing’s costly “Bird’s Nest,” which has a construction price of $460 million and costs $10 million annually to maintain—cleaning up the Seine presents a hopeful legacy. It will also serve as a model for other major cities aiming to enhance their waterways, such as Berlin’s Spree River and Boston’s Charles River.

Dan Angelescu, a scientist monitoring the Seine’s water quality for Paris, remarked to the Associated Press, "This will send ripples around the globe as many cities are observing Paris closely."

This article was first published in June 2023 and updated on July 9, 2024, to reflect the latest information.