How dangerous is the Seine for Olympic athletes?

TThe Olympics are about the unexpected. And for marathon swimmers and triathletes, that includes a notoriously unpredictable partner – the location, which is typically an ocean, a lake or, in the case of the Paris Olympics, the city’s historic Seine River.

As iconic as the Seine is, with its picturesque views of city landmarks such as the Eiffel Tower and the Musée d’Orsay, it is also a contaminated body of water. There are enough risks to human health that the city has banned swimming in the Seine for more than 100 years.

But Olympic organizers wanted to change that, even temporarily, by organizing the swimming marathon and the swimming portion of the triathlon in the river, and invested $1.5 billion in building a huge tank under the Seine to retain rainwater. during heavy rains and storms. The water from the tank is then gradually channeled to a wastewater treatment plant, where it is treated and then the clean water flows back into the Seine. Engineers also upgraded sewage pipes on boats and docks along the Seine to limit the amount of contaminated sewage running into the river.

See more information: Inside the Billion-Dollar Effort to Clean the World’s Most Romantic River

But as of late July, tests continue to reveal unsafe levels of bacteria – particularly E. coli and enterococci – in the water. Levels vary depending on a number of factors, from the amount of rain to the number of sunny days and the speed of the river current. From June 24 to July 2, the river was acceptable for swimming by European standards on six of the nine days, according to weekly reports published by Paris authorities.

Still, in an effort to demonstrate to the world their confidence in the cleanliness and safety of the Seine, Paris Mayor Anne Hidalgo and the president of the Paris 2024 organizing committee, Tony Estanguet, took the plunge for a few minutes on July 17, until even dunking their heads underwater for a few freestyle strokes. “After the Games we will have a pool in the river for everyone”, Hidalgo he said after diving.

Whether this will happen remains uncertain. The final decision on whether to hold the swimming marathon and the swimming portion of the triathlon in the river will be taken by the respective sports governing bodies, depending on the data collected by the Paris authorities the day before and the morning of the scheduled events. According to Reutersa meeting with interested parties – Paris authorities, Paris 2024 Olympic authorities, the sports federation, regional authorities and Meteo France (the country’s meteorological organizations)— will take place at 3:30 am, Paris time, on each day of the event, for the final decision on whether athletes will compete in the Seine.

This assumes, of course, that laboratory tests for E.coli can be done quickly enough to provide reliable measurements, says Natalie Exum, assistant professor of environmental health and engineering at the Johns Hopkins Bloomberg School of Public Health. “It takes about 24 hours to grow E. coli bacteria,” she says. “There may be some other proxy indicator for bacteria that they’re using, but it’s not like you can stick something in water and know how many E. coli are present at that instant.”

If the river continues to have fluctuating levels of pollutants, there are health risks that athletes could face if officials decide the river is safe to swim during the scheduled event. The most common organic contaminants – E. coli and enterococcal bacteria – are responsible for gastrointestinal illnesses including diarrhea, abdominal cramps, vomiting and nausea – something that is not welcomed by anyone, especially athletes who need to be in perfect physical condition to to compete. “There are certain pathogenic strains of E. coli that cause what we call traveler’s diarrhea,” says Dr. Susan Kline, professor of medicine at the University of Minnesota School of Medicine. Kline says anyone exposed to untreated water can expect similar risks to what campers might face in rivers or lakes, which include parasites like giardia.

Then there are the possible chemical pollutants from industrial waste runoff, which can pose serious health risks as well as skin irritation. And having cuts or open sores on your skin can also increase your risk of any infection caused by whatever’s in the water, says Dr. Timothy Brewer, professor of medicine in epidemiology at the University of California, Los Angeles.

See more information: See how Paris plans to make this iconic, polluted river navigable again

It’s not as if the Paris sewer system and the river were intentionally linked. During heavy rains, sewage flowing into water treatment plants mixes with overflowing rainwater, and the facilities’ normal treatment systems become overwhelmed by the sheer volume of water that needs to be treated. Some of this untreated water flows into the Seine, contaminating the river. “We call it the first flush,” Exum says of the flood of water that gushes through wastewater treatment plants after a rain. “I wouldn’t advise anyone anywhere in the world to swim in a river 24 hours after a big discharge,” she says. “The entire sewage system is designed to manage the low flow capacity of the toilets, not the water jet. These systems were not designed for the intensity of rainfall events we are now seeing as a result of climate change.”

Even with heavy rain, normally a certain amount of sewage-derived bacteria can also be eliminated by the sun’s ultraviolet rays and higher temperatures. But a rainy and cloudy spring in Paris left conditions ripe for bacteria to thrive in the river. And the forecast for the first week of the Games is cloudy. Even with overflow tanks built to collect sewage during rains, the river continues to host dangerous levels of bacteria.

The tank is an important but not enough step to truly clean the Seine, says Exum. “Disconnecting the stormwater system from the sewer system throughout Paris is what essentially needs to happen, but it takes decades and is an iterative process.” Cities like Paris, which don’t have many green spaces to absorb rainwater, end up sending most of it to the underground sewage system, which only increases river pollution.

See more information: Paris Mayor Anne Hidalgo has a lot to do with the 2024 Olympics

Organizers told Reuters that the water of the Seine will be tested twice a day as the Games approach, and that there is an alternative location for the marathon swim in Vaires-sur-Marne, and a contingency plan to postpone the triathlon or abandon the triathlon altogether part of the swim if the river is considered unsafe on competition days. But no official announcement has been made and, for now, the two Sena events are scheduled for the city’s river.

The uncertainty is adding additional stress to an already complicated situation for athletes, who would like to receive a decision on where and whether they will compete, and the assurance that they will be safe in doing so. Team USA Open Water Coach Ron Aitken counted USA today that the lack of decision is “irresponsible.”

“I think even if there’s a 1% chance the race won’t go ahead because of cleaning or lack of cleaning, you need to have a backup plan.“, Aitken said. “It’s the Olympics.”