What happens if the Seine isn't clean enough in time for the Olympic triathlon? (2024)

With the Paris Olympics in full swing, things are getting a little dicey for the competitions that rely on the Seine, that river that runs through the heart of the city.

The Seine played a starring role in the opening ceremony, serving as the entryway for the athletes and the torch on nearly 100 boats that cruised to the Trocadéro during what became a heavy rainstorm.

Now the Seine has to perform in a different way. It has to be clean enough for swimmers in the triathlon and the long-distance swimming races that are scheduled for the next week. It’s not going so well.

That rain that wreaked a bit of havoc with the Friday night festivities, sent sewage and street run-off into the river when the sun and warm, dry weather was supposed to be delivering a natural clean-up. Daily testing has shown pollution levels are too high for athletes to swim safely in the river.

Now what? Here’s a state of play for the Seine and the athletes who are supposed to compete in it.

What’s in the river?

The Seine is a lot cleaner than it used to be, but it’s hard not to notice the detritus — random cans, bottles, food wrappers, and everything else that people who eat and drink by the river sometimes toss into it and other stuff that blows in.

That’s the stuff you can see. There’s also an unhealthy amount of bacteria most closely associated with sewage contamination — E. coli and enterococci. Wastewater flowed into the Seine for hundreds of years. It mostly doesn’t now, but some still does during a heavy rainstorm when the water overwhelms the modernized sewage system.

The government built a $1.5 billion underground tunnel and water tank under the Austerlitz train station that is supposed to capture the extra water. But the tank can only hold so much water — 13.2 million gallons, enough to fill 20 Olympic-size swimming pools.

How do they determine it’s still too dirty?

Every morning at 3:30 a.m., Paris 2024, the DRIEAT, which is the regional environmental agency, the City of Paris and the prefecture of the Île-de-France region are involved in carrying out water quality tests. They relay the results to the technical and medical officials with World Triathlon and World Aquatics.

The past two days, the river has failed the tests, causing organizers to cancel training sessions in the river for triathletes. They were able to train on the course where they will run and cycle.

When are the races?

The men’s triathlon is scheduled for Tuesday. The women’s race is scheduled for Wednesday. The mixed relay is scheduled for next Monday. The open-water swims are scheduled for the end of next week on Aug. 8 and 9.

What happens if it’s too dirty

The initial plan is to delay the triathlons. The last resort plan is to turn the competition into a duathlon rather than a triathlon, so just cycling and running.

The races are at 8 a.m., so athletes will learn at dawn whether they will toe the start line Tuesday and Wednesday.

From a placement standpoint, the swim has become less important as triathlon has evolved. No one wins the race during the swim and few lose it then. Most triathletes survive the swim and the real racing comes down to the final leg, the run. Still, no swim would be a shame.

The marathon swim races (6.2 miles) would shift to the waters of Vaires-Sur-Marne, east of Paris, where the canoe races are taking place.

Why isn’t there a Plan B for the triathlon?

There isn’t another body of clean open water near the roads in the center of the city where the athletes will swim and bike. Finding an alternate course for a swim is one thing. securing an alternate course for a swim, a cycle and run is a logistical nightmare, given security concerns and television requirements.

How does the river become clean?

The marine scientists insist that warm dry weather and sun kill the bacteria. Also, the natural flow of the river helps flush out the dirty stuff, assuming there isn’t another storm that sends more dirty water downstream.

What’s the forecast?

Tuesday is supposed to be very hot and very dry with temperatures reaching the 90s, not ideal for an endurance test.

After trouble could be on the way. There are not-insignificant chances of rain (35-45 percent) on Wednesday and Thursday. After that, there is no rain in the forecast for five more days, but the further out you go, the less reliable the forecast is.

How do the athletes feel about this?

“Control the controllable” is the mantra of any successful athlete. The weather is the least controllable thing out there. The best ones are used to this in triathlons, especially those contested in urban areas. That’s why the world governing bodies of swimming and triathlon have those rules in the first place.

That said, it’s the Olympics. They want to do a proper triathlon, and plenty of them have risked their health before in waters that were less than pristine. Most would jump at the chance to do it again in the center of Paris.

As for the marathon swimmers, who also swim in some surprising bodies of water, just tell them where the race is and they will show up with their caps and goggles ready to tear up whatever water they are told to jump into.

(Top photo of the Seine and Pont Alexandre III, the starting point for the triathlons, this week: Sven Hoppe / picture alliance via Getty Images)

Matthew Futterman is an award-winning veteran sports journalist and the author of two books, “Running to the Edge: A Band of Misfits and the Guru Who Unlocked the Secrets of Speed” and “Players: How Sports Became a Business.”Before coming to The Athletic in 2023, he worked for The New York Times, The Wall Street Journal, The Star-Ledger of New Jersey and The Philadelphia Inquirer. He is currently writing a book about tennis, "The Cruelest Game: Agony, Ecstasy and Near Death Experiences on the Pro Tennis Tour," to be published by Doubleday in 2026. Follow Matthew on Twitter @mattfutterman