PARIS — The swimming portion of a practice run for the Olympic triathlon was canceled Sunday due to concerns about water quality in the Seine River.

However, Paris officials remain confident that triathletes will be able to swim in the city’s famed waterway during the actual events this coming week.

The men’s triathlon is scheduled for Tuesday, with the women’s event set for Wednesday. Triathletes were supposed to familiarize themselves with the course on Sunday, but organizers decided to cancel the swimming leg after discussions involving representatives from World Triathlon, city and regional authorities, and other decision-makers who reviewed water quality tests.

The water quality in the Seine is closely linked to the weather. Following heavy rains during Friday’s Olympic opening ceremony and continued showers on Saturday, officials decided to cancel the test swim. With no more rain in the forecast, they expect athletes will still have the opportunity to race in the Seine.

“We’ve seen what were the dynamics of the Seine over the past few weeks, and that’s what makes us confident,” Paris Deputy Mayor Antoine Guillou said at a news conference Sunday.

Olympic organizers echoed the confidence of Paris officials. “We are still very confident with the weather forecast for the next 48 hours; the water quality will improve,” Paris 2024 spokesperson Anne Descamps said. “Thanks to all the work that has been undertaken by our public stakeholders, we saw the water quality of the River Seine has improved significantly.”

If concerns persist when race time arrives, the first backup plan is to postpone the triathlon events by a few days. If water quality remains unsatisfactory, the swimming portion will be canceled, and athletes will compete only in the running and biking segments.

Swimming in the Seine has been banned for over a century due to poor water quality. Paris invested 1.4 billion euros ($1.5 billion) to prepare the river for the Olympics. Measures taken included constructing a giant basin to capture excess rainwater and prevent wastewater from flowing into the river, renovating sewer infrastructure, and upgrading wastewater treatment plants.

Despite the cancellation of the practice swim, triathletes have expressed hope that the waters will be clean enough for them to swim in. Daily water quality tests in early June indicated unsafe levels of the fecal bacteria E. coli, but recent improvements have been noted. Paris Mayor Anne Hidalgo even took a dip in the river less than two weeks before the Olympic events were set to start to demonstrate the waterway's improved condition.

World Triathlon officials share the belief that the Seine will be suitable for swimming by Tuesday and Wednesday. Torin Koos, a spokesperson for World Aquatics, said they will “revisit the water quality of the Seine” closer to the marathon swimming events, which have a training day on Aug. 7. — Agencies