The attempt to clean up the Seine River has failed! Belgium has withdrawn from the three-discipline event after a swimmer in the Seine River fell ill.

The Belgian Olympic Committee announced on Sunday that they will withdraw their team from the mixed relay triathlon event at the Paris Olympics after one of their swimmers, Claire Michel, fell ill.

Claire Michel, who was set to compete in the women's mixed relay triathlon on Wednesday, "unfortunately fell ill and will have to withdraw from the competition," the Belgian Olympic Committee and Belgian Triathlon Federation said in a statement.

The Paris 2024 organizing committee has not made an official statement about Michel's illness, but announced on Sunday evening that the mixed relay triathlon event will take place on Monday at 8 a.m. The swimming leg is planned to take place in the Seine River.

The statement from the Belgian committee did not provide details about Michel's illness but was issued following concerns about the water quality of the river. The organizers reported that water quality tests conducted on the day of the individual triathlon races showed "very good" levels of bacteria.

On Sunday night, representatives from World Triathlon and the International Olympic Committee, along with the Paris Games organizing committee and local weather authorities, reviewed water quality tests. The results indicated that the water quality at the triathlon venue had improved in recent hours and would be within the limits set by World Triathlon.

Daily water quality tests measure levels of fecal bacteria, including E. coli, in the Seine River. The water safety guidelines of World Triathlon and the European Union's directive of 2006 specify threshold values for a range of E. coli levels.

According to World Triathlon guidelines, E. coli levels up to 1,000 colony-forming units per 100 milliliters can be considered "good" and may allow competitions to proceed.

The World Triathlon medical commission considers water quality analysis, sanitation checks, and weather forecasts when deciding whether to proceed with races.

Decisions are typically made at early morning meetings on the day of the event.

However, with the announcement on Sunday evening that the race would take place on Monday, the organizers stated that they are accommodating athletes' requests for additional preparation time.

Leading up to the individual triathlon events, concerns about water quality prompted the organizers to cancel the swim portion of two trial runs to allow athletes to familiarize themselves with the course and to postpone the men's race by a day.

The Seine River swim trials scheduled for Saturday and Sunday before the mixed relay triathlon were also canceled due to bacterial levels in the water.

The Belgian committee expressed hope that lessons would be learned for future mixed relay triathlon events at the Olympic Games. "We are thinking about ensuring training days, competition days, and competition formats, all of which must be clarified beforehand and ensure that there is no uncertainty for athletes, delegations, and supporters," they said.

Swiss officials reported on Saturday that mixed relay triathlon athlete Adrien Briffod, who also competed in the Seine River on Wednesday, had developed a stomach infection. However, they stated that it was "impossible to say" whether it was related to swimming, and other delegations informed them that none of their mixed relay triathletes had reported any stomach issues.

Swiss officials provided an update on Sunday, stating that Simon Westermann, who was selected to replace Briffod, also had to withdraw due to a gastrointestinal infection. Westermann had not participated in any swims in the Seine River, the statement said. The Swiss team still plans to compete in the mixed relay event on Monday.

Norwegian mixed relay triathlon athlete Vetle Bergsvik Thorn fell ill a day after competing in the men's individual triathlon event. Thorn told Norwegian broadcaster NRK that he woke up the next day with abdominal pain and nausea but thought it could be food poisoning. He said he felt better later in the day and was planning to compete in the scheduled mixed relay event on Monday.

Arild Tveiten, sports director of the Norwegian Triathlon Federation, stated that the cause of Thorn's illness is still unclear.

"We are thinking what everyone is thinking: that maybe it's because of the river. But we don't know. It could be because of the river, it could be because of something else," Tveiten told NRK. "Doctors are leaning towards the possibility of food poisoning. That's what the symptoms indicate."

The marathon swimming event is scheduled to take place in the Seine River on Thursday and Friday.

Five out of eight male swimmers in the 1,500m freestyle event on Sunday evening have signed up for the 10km marathon swim.

Silver medalist Daniel Wiffen from Ireland, who had previously won gold in the men's 800m freestyle event, stated that he will not train in the Seine River beforehand: "I don't want to deal with any illnesses."

Instead, he said he will train in pools around Paris, even if it means "training blindly."

In conclusion, concerns about water quality and its impact on athletes' health have prompted withdrawals and raised questions about future events in open water venues. The ongoing monitoring of water quality and swift decision-making based on health and safety considerations will be crucial for ensuring successful competitions in such environments.