One of the most remarkable features of the 2024 Summer Olympics in Paris was that numerous events were staged outdoors, in and around the French capital’s monuments and streets and along the River Seine, the scene of the July 26th opening ceremony.
While the backdrops made for stunning images, the decision by the organisers of the Games to hold swimming and triathlon events in the Seine was increasingly questioned before and during the Olympics because of persistent high levels of pollution in the water, notably bacterial pollution from faecal matter. The latter is primarily caused by sewage leakages, which were exacerbated by heavy rainfall over winter and the months leading up to the games.
The quality of the water is tested daily by Eau de Paris, the publicly owned company that manages water supply and collection for the Paris municipal authorities. Before the Games, the pollution data was published on a weekly basis by Paris City Hall on its website, but it suspended the publications on July 24th. Instead, the information was passed on to the Organising Committee of the Paris 2024 Olympic and Paralympic Games (the COJOP), which had full discretion as to whether to make the data public or not. “During the period of the Games, only the organisers are authorised to communicate the data on the quality of the water,” said Paris City Hall.
Mediapart however obtained access to the confidential data, which is published in the box below. The data revealed that between July 27th, the day after the opening ceremony of the Olympics, and August 5th, the quality of the River Seine’s water, in which a number of swimming events took place, only met the required standards on two days, July 30th and 31st. On all the others, the levels of the bacteria Escherichia coli (E. coli) and intestinal Enterococcus exceeded the safety ceiling (see box below) as defined by the international federations World Aquatics and World Triathlon, which are recognised by the International Olympics Committee as the governing bodies of their respective sports.
Questioned, the COJOP did not challenge Mediapart’s conclusions from the data, except concerning August 5th when the Triathlon Mixed Relay event, which began with a 300-metre swim in the Seine, was held. The Eau de Paris data for that day showed that the levels of E. coli and Enterococci were higher than the ceiling levels set by World Aquatics and World Triathlon. More precisely, it recorded 436 colony-forming units (CFUs) of Enterococci per 100 millilitres (ml) of water from the Seine, whereas the federations fix a ceiling of 400 CFUs per 100 ml. The sample was taken by Eau de Paris at the port du Gros-Caillou, a central-Paris riverside quai between the bridges of the Invalides and Alma, and which is one of the four locations it used for testing.
Questioned by Mediapart, the COJOP described the result as “hovering around the limit” and said the port du Gros-Caillou “is situated outside the route of the triathlon”. In fact, it was situated right beside the route.
Several athletes who swam in the Seine during the games have fallen ill with intestinal complaints, although until now no firm link with the water pollution has been established. The latest case is Irish athlete Daniel Wiffen, who took part on Friday in the men’s ten-kilometre marathon swimming race. Wiffen missed Sunday’s closing ceremony, where he was to be Ireland’s flag bearer, after seeking hospital treatment for his condition.
Early on in the Games, Belgian athlete Claire Michel was hospitalised with E. Coli after competing in the July 31st triathlon event in the Seine. Other less severe cases have been reported and treated by team doctors, including one Norwegian and two Swiss triathletes, and a German swimmer.
Enlargement : Illustration 1
Furthermore, the ceiling safety levels regarding athletes’ exposure to the bacteria pollution, as defined by World Aquatics and World Triathlon, allow for higher amounts of CFUs per millilitre than the French health authorities have established for waters used for public bathing. That suggests it will be unlikely that the municipal authorities succeed with their hope of opening the Seine to public swimming areas in 2025, as a legacy of the Games.
The pollution levels are the result of the dilapidated state of the sewage treatment network upstream from Paris, which the Seine runs through from east to west, and leakage from unrepaired drains under the capital. Added to this has been the heavy rainfall over recent months which has both added to the amount of dirty water spilling into the Seine, and also increased the speed of the water flow which during the games reached close to 300 cubic metres per second, almost double the usual. As a result, the bacteria travel faster, with less time for them to degrade under the effects of ultraviolet light from the sun.
That is despite a 1.4-billion-euro project to improve the quality of the waters in the Seine which was put in place ahead of the Games, including the building of an overflow tank near the riverside Austerlitz railway station for holding sewage and excess water during heavy rainfall.
According to both Paris City Hall and the prefecture of the greater Paris region, the Île-de-France, it is the COJOP that takes the final decision on whether or not an event should take place. However, the August 5th Triathlon Mixed Relay event which went ahead despite the numbers of E. coli and Enterococcus CFUs showing higher than the recommended threshold, was decided by World Triathlon, according to the COJOP.
The COJOP also insisted that a decision to postpone a familiarisation session on August 6th for a marathon swimming event was taken by the World Aquatics federation after the poor results of pollution tests.
Sub-contracted by the capital's authorities to take part in 2023 in what was called a “test event” ahead of the Games, Fluidion, a private water quality monitoring company based near Paris, sounded the alarm at the pollution levels it discovered at the time. “In 2023, we gave an alert about the presence of a very large and quite various quantity of bacteria present on faecal particles,” said the company’s managing director Dan Angelescu. “They were aware of it, and they made their choice knowingly.”
Fluidion did not participate in water monitoring during the Games but it does monitor pollution for Paris City Hall in the Bassin de la Villette, a vast water basin that links two canals in north Paris and where public swimming is allowed. Angelescu said that while the Paris Summer Olympics were “extraordinary, perhaps the most wonderful in history”, he regretted that there was “in speeches at the moment on the pollution of the Seine a bit too much of political aims and too little of science”.
According to several experts in water pollution contacted by Mediapart, the strong presence of E. coli and Enterococci cannot be underestimated. Apart from the threat they pose to health, the concentration of the bacteria indicates the presence in the water of other pathogenic organisms, such as viruses, parasites, and other types of bacteria.
“For the Olympic Games it’s not a problem, the athletes are young and in good health,” claimed a pollution specialist, who asked not to be named. “But afterwards, what will happen when swimming will be opened up to the public at large?”
-------------------------
- The original French article on which this report is based can be found here.
English version by Graham Tearse