PARIS (AP) — With the Paris Olympic Games With less than two weeks to go until the Games, one question looms: will the Seine be clean enough for the athletes to be able to swim in it?
A triathlon and a swimming marathon are planned in the Seine, where swimming has been banned for more than a century. Despite the city’s efforts to clean up the long-polluted river, tests have found the water unfit for human consumption in recent weeks, and cleaner on other days. The games will run from July 26 to August 11.
To clean up the river, Paris has invested 1.4 billion euros ($1.5 billion) in building infrastructure to capture more stormwater when it rains – the same water that contains bacteria-laden sewage that enters the river during periods of heavy rain and makes it unsafe for swimming.
FILE – A man walks in the Austerlitz wastewater and stormwater storage basin, which is intended to make the Seine River swimmable during the Olympics, in Paris, during its inauguration on May 2, 2024. (Stephane de Sakutin/Pool Photo via AP, File)
In May, Parisian authorities have inaugurated a gigantic underground water storage basin Next to the Gare d’Austerlitz, this basin aims to collect excess rainwater and prevent wastewater from flowing into the Seine. This basin, which can hold the equivalent of 20 Olympic swimming pools of wastewater, will now be treated. It is the centerpiece of the major infrastructure works that the city rushed to complete in time for the Games, but also to guarantee Parisians a cleaner Seine in the years to come.
But a few bouts of heavy rain could push E. coli levels above the limit of 900 colony-forming units per 100 milliliters that the World Triathlon Federation has determined is safe for competition.
“The Seine is not a special case,” said Metin Duran, a professor of civil and environmental engineering at Villanova University who has conducted research on stormwater management. “It’s really a complex and very expensive problem.”
Paris, like many older cities around the world, has a combined sewer system, meaning that the city’s sewage and stormwater flow into the same pipes. In the event of heavy or prolonged rainfall, the capacity of the pipes is reached, meaning that raw sewage flows into the river instead of being taken to a treatment plant.
Every day, the Eau de Paris monitoring group tests the river water, giving results that showed dangerous levels of E. coli in recent weeks followed by results in early July which showed an improvement.
Paris Olympics organisers have said that if heavy rain affects the flow of the Seine during the Games, The triathlon would no longer include a swimming part — and the marathon swimming competition would be relocated to the Stade nautique de Vaires-sur-Marne, in the Paris region.
FILE – Athletes swim in the Seine River during the first leg of the women’s triathlon test event for the Paris 2024 Olympics in Paris, Aug. 17, 2023. In 2024. (AP Photo/Michel Euler, File)
“It’s not very common, but it has happened several times,” said Ollala Cernuda, communications manager for World Triathlon, an international body for the sport, about the possibility of the swimming portion being canceled.
“And that’s always linked to water quality issues,” Cernuda said.
But organizers remain optimistic that drier, sunnier weather than the French capital experienced in June will allow events to go ahead as planned, thanks to infrastructure improvements. The sun’s ultraviolet rays kill bacteria like E. coli in water.
An AP analysis of weather data showed that in 2024, Paris had the second-most rainy days of any year since 1950, surpassed only by 2016.
What is important for the water quality of the Seine is that there have also been few periods without rain.
Paris has experienced only one week of drought this year, in early June, while between 1950 and 2020 it was typical for the city to experience at least three such periods before the end of June, according to the analysis.
FILE – A worker walks in a tunnel connected to the water storage reservoir under construction for the Seine River, Nov. 29, 2023, in Paris. (AP Photo/Aurelien Morissard, File)
“Precipitation forecasts have become much more accurate up to a week in advance,” said Jennifer Francis, a scientist at the Woodwell Climate Research Center in Massachusetts. “But the seasonal patterns of decades past no longer provide reliable guidance in our increasingly warming world.”
As the Games approach, the heated debate over the cleanliness of the Seine has become a source of frustration for some athletes like Léonie Périault, a French triathlete who won a bronze medal at the 2020 Tokyo Olympics.
“Every time I meet someone, they’re afraid I’ll swim in the Seine,” says Périault. “But I’ve been swimming in this river for several years. In youth competitions, we regularly swam in the Seine and we never had any problems.”
Last year, Périault took part in a test event in the Seine.
“The setting was incredible with the Eiffel Tower as a backdrop and the water conditions were no worse than anywhere else in the world,” she said.
FILE – Barges sail on the Seine River near the Eiffel Tower during a rehearsal for the opening ceremony of the Paris 2024 Olympic Games, June 17, 2024, in Paris. (AP Photo/Thomas Padilla, File)
On Saturday, French Sports Minister Amélie Oudéa-Castéra dived to demonstrate that the famous river is clean enough. Paris Mayor Anne Hidalgo also said she would swim in the Seine this week.
Dan Angelescu, founder and CEO of Fluidion, a water monitoring company based in Paris and Los Angeles, said there have been improvements in the river since the city’s new infrastructure came online, but the Seine’s water quality remains fragile. His company has been measuring contamination levels in the Seine for several years.
Angelescu said it was difficult to predict, using data from previous years, what might happen later this month – since the water storage basin and other infrastructure were not operational until a few months ago.
“It’s hard to say,” Angelescu said, speaking in early July after the Seine’s water tested cleaner than several weeks earlier.
“Seeing such a dramatic and rapid improvement could be a sign that something is working,” he said.
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AP reporter Mary Katherine Wildeman in Hartford, Conn., contributed to this report. Naishadham reported from Washington.
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