Billion Dollar Effort To Clean Up The Seine for Paris 2024 Well Underway

Cutting through Paris, the Seine has been at the heart of the city since it was founded by ancient Romans. The easy access to water was a huge draw for the people of the Middle Ages who built Paris into then the largest city in Europe and an important commercial hub. Eventually, the Eiffel Tower, Notre Dame Cathedral, the Louvre, and the Musee d’Orsay were built along its banks. These iconic monuments draw millions of tourists to the Seine, as they float down the part of the river that flows through the very center of Paris. Some Parisians chart the waters on their own boats, and more cross daily on one of the 37 bridges connecting the Left and Right Banks.

Paris 2024 organizers plan for the river to play a central part in the Games as well. Not only will the Seine play host to the Opening Ceremonies, with athletes floating down the river on barges dedicated to their respective countries, but several events will also be held in the river itself. Triathletes and open water swimmers will set off from the Alexandre III bridge during both the Olympics and the Paralympics.

The issue is that the Seine’s water isn’t exactly the cleanest. Swimming in it has been banned since 1923. Cleaning up the river and making the organizers’ plan a reality takes a multi-pronged plan that costs 1.4 billion euros (1.5 billion USD). It’s been underway since the city won the Olympic bid.

Pollution issues with open water are not a new phenomenon at the Summer Olympics. At the 2016 Games in Rio, waterborne viruses were a major concern in Guanabra Bay, and at Tokyo 2020, water quality issues (as a result of pollution) in Tokyo Bay were a major storyline leading all the way up to the Games.

Though progress has been made in the clean-up effort at the Seine, it will take many more months to complete. In early 2023, officials invited journalists from media outlets like TIME and The New York Times to get an inside look at what they’ve been doing to clean up the river.

How Much Could There Be to Clean Up, Really?

The short answer is a lot. The Seine has been used as a dumping ground for centuries. During the 16th century’s religious wars, bodies of Protestants and Catholics alike were thrown in. In 2007, 55 bodies were pulled from the water. Plenty of debris from nights out has made its way in. Local government told TIME that “360 tons of large items [like bicycles and electronics] are hauled out of the Seine every year.”

But the biggest problem is the wastewater. Like many rivers that cut through centuries-old cities, tons of sewage and industrial wastewater has been dumped into the Seine. Paris’ sewer system funnels both rainwater and wastewater. When storms overwhelm the system—which happens about 12 times a year according to Samuel Colin-Canivez, the city’s lead engineer for the sewage projects—everything gets released into the Seine.

Cleaning up the Seine is not a new idea. In 1990, then-Paris mayor (and later French president) Jacques Chirac promised a grand clean-up of the Seine and that in three years “[he] will swim in the Seine in front of witnesses to prove that the Seine is a clean river.” That plan was not fulfilled, and Chirac died in 2019 without dipping a toe into the river.

A year after his death, the Olympic bid revitalized Chirac’s dream. And once the Games were awarded to Paris, there was suddenly a hard deadline for the clean-up.

The Swimming Plan

Two main things need to happen for the “Swimming Plan” for Paris 2024 to work. First, the pollution already in the water needs to be cleaned up. Second, officials need to find a way to ease the burden on the current sewage system and stop waste from being released into the Seine.

“We’re not purifying the Seine,” Colin-Canivez told The New York Times. “Our approach is to keep untreated water from being dumped into the Seine.”

At the center of this plan is a 700-meter tunnel. That tunnel connects to an underground storage tank near the Austerlitz train station that Colin-Canivez and his team are building. When both are completed, they will be able to hold 13.2 million gallons of water. That’s about 20 long-course pools, and it’s one of five big engineering projects aimed at dealing with storms. The team hopes that this will reduce the number of times Paris’ sewage system is overwhelmed from 12 to two times per year. When it’s finished, the tunnels will divert the collected rainwater from the sewage system. Instead, it will flow to the bank across, be slowly released into the sewer network, and eventually treated at a downstream treatment plant.

As for the current pollution, officials added special treatments to upstream sewage treatment plants, aiming to cut the level of harmful fecal bacteria in the water by 100x. Teams have been going door to door trying to convince homeowners to let them properly hook their pipes up to the sewer system. In some Paris suburbs, builders originally connected sewage pipes to the rainwater system. The only way to determine which houses still operate like this is to dig up the pipes and check.

Progress has been made. Teams have been testing the Seine’s waster since 2020. Last summer, approximately half the samples met their target. When they tested the part of the river their planning to use for events, the results were “90% ‘fair’, meaning an Olympic committee would have to decide whether to proceed.”

There’s a lot riding on The Swimming Plan. Games organizers have no alternative for where the triathlon or open water swimming would be held. If it rains the entire week before the Games, deputy mayor Pierre Raabadan told The New York Times “we know the quality of the water—even with all the work we’ve done—probably won’t be excellent.” The Austerlitz tank will likely be full. Organizers will have no choice but to postpone races, wait a few days, and test the water quality again.

The Legacy

Organizers hope that the benefits from the river cleanup won’t just be felt by the Olympians competing. Mayor Anne Hidalgo has promised that by the summer of 2025, locals will have access to about 20 swimming areas along the Seine.

There are also environmental benefits to consider. Officials predict that cleaning up the river will bring more fish back and restore the foliage along the banks.

They’re also hoping the project will serve as an example for other cities looking to clean up their rivers. According to TIME, Los Angeles—the host of the 2028 Olympics—has already sent sanitation officials to observe the Seine cleanup process.

The countdown to the 2024 Games is on, and officials are continuing to plug away at their master plan. But at the end of the day, they will also be crossing their fingers that it doesn’t rain.

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16 days ago

It’s a sh**ty situation

Kynae Tesw
16 days ago

I’m from France, La Seine is dirty as hell I still don’t know how are they going to clean it efficiently

Reply to  Kynae Tesw
16 days ago

Dam it and chlorinate the crap out of it 🤣😂.

Kynae Tesw
Reply to  SHRKB8
16 days ago

Bikes, electric scooters, garbage, and even corpses 🤢 (because yeah, some people use to jump in the Seine unfortunately…)

16 days ago

August this year they are supposed to be swimming a world cup event on the proposed Olympic course, suppose organisers will just see how many get sick from that event before they come up with a contingency venue 🤦.

Reply to  SHRKB8
16 days ago


About Sophie Kaufman

Sophie Kaufman

Sophie grew up in Boston, Massachusetts, which means yes, she does root for the Bruins, but try not to hold that against her. At 9, she joined her local club team because her best friend convinced her it would be fun. Shoulder surgery ended her competitive swimming days long ago, …

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