The men's triathlon at the Paris Olympics will not go ahead as planned on Tuesday as pollution levels in the Seine remain too high, World Triathlon said in a statement, dealing a blow to organizers and leaving athletes facing more uncertainty.

The race was postponed until Wednesday at 10:45 a.m. local time, immediately after the women's event, which is scheduled for 8 a.m. that day.

Organizers had previously said they were confident water quality would improve in time for the race after heavy rains last Friday and Saturday dirtied the river.

"Despite the improvement of water quality levels over the last hours, the readings at some points of the swim course are still above the acceptable limits," they said early on Tuesday.

Should levels of bacteria remain too high by Wednesday morning both the men's and women's races are likely to be postponed to Friday, the contingency day reserved for the events.

If by Friday the water quality is still not good enough, the swim leg will be scrapped and athletes will compete in a duathlon instead. For the mixed triathlon relay event on August 5, the contingency day is August 6.

Adding to the risk of another postponement, France's state weather service has forecast a risk of thunderstorms on Tuesday evening and overnight.

Australia's Olympic team chief Anna Meares said news of the postponement had not deterred the triathletes.

"The athletes are really looking forward to having that stage and that platform to perform on," she told reporters. "They actually want to swim in the river."

'A lot of disappointment'

French triathlon federation technical director Benjamin Maze told FranceInfo they were taking steps to help athletes deal with the situation.

"Of course there is a little bit of anger and a lot of disappointment," he said.

The federation had been working with psychologists to help athletes prepare mentally for the uncertainty, Maze added.

Around 50 spectators had gathered on the sun-drenched Invalides bridge by 7 a.m. to watch the race, only to learn it had been postponed.

Magnus and Kristine Hagelsteen from Lund, Sweden, had packed pains au chocolat to have for breakfast while watching the race and cheering on Norway's Kristian Blummenfelt, who won gold at the Tokyo Olympics.

"It's a pity for everyone but especially for the ones that are going to do the triathlon; I would be so disappointed - you're nearly there, ready to start, and then it's canceled," said Magnus, who planned to come back on Wednesday.

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For Ortrun Guendisch, visiting from Munich, the postponement meant she and her 14-year-old son Adrian would miss the event entirely as they were starting their journey home later in the day.

"We actually woke up very early to come here and we found out when we got here that it's canceled, so we are pretty disappointed," Guendisch said.

Paris authorities have invested heavily to make the Seine swimmable as a key legacy of the Games, and spent $1.5 billion on wastewater infrastructure to contain sewage and minimize spillage into the waterway.

Paris Mayor Anne Hidalgo took a dip in the river herself earlier this month, in a bid to convince doubters. City authorities have announced plans for three Seine swimming sites to open to the public by June next year.

"For Parisians it will be fabulous if you can go swimming in the river, and it should be like this, it should be that you can swim in the river in the city," said Kristine Hagelsteen.

Purposeful E. coli exposure

However the gamble that the river would be clean enough on the day of the triathlon was never guaranteed to pay off, especially as water quality varies widely day-to-day. Rainfall often causes sewer systems to overflow into the river, significantly increasing concentrations of infection-causing bacteria such as E. coli.

Seth Rider, one of 55 triathletes entered in the men's race, has been taking unconventional measures to prepare for exposure to bacteria.

"We know that there's going to be some E. coli exposure, so I just try to increase my E. coli threshold by exposing myself to a bit of E. coli in your day-to-day life," the U.S. athlete said in a press conference on Saturday.

"Just little things throughout your day, like, not washing your hands after you go to the bathroom and stuff like this."

Bacteria aside, the Olympic triathlon course was conceived to maximize the wow factor, with the river swim a key element.

After diving into the Seine from a pontoon next to the Alexandre III bridge, athletes are set to race past the Musée d'Orsay and Grand Palais during the bike and run stages before ending back where they started.

Crossing the finish line on the bridge, they will be framed by stone columns topped with gilt-bronze statues of Pegasus, with the golden dome of the early 18th century Invalides monument as a backdrop.

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