Olympic organizers cancelled a second day of triathlon training in the River Seine scheduled for Monday following weekend downpours that polluted the waterway in Paris. However, they remain "confident" that the medal events will proceed this week as planned.

In a joint statement, Paris 2024 organizers and World Triathlon announced the cancellation of Monday's swimming training session due to water quality levels that did not meet the necessary standards. This follows the cancellation of another swimming training session on Sunday for the same reason.

The men's individual triathlon is set to begin on Tuesday at 8:00 am (0600 GMT), with the women's individual event scheduled for Wednesday. These events mark the first Olympic competitions to be held in the Seine, with marathon swimming slated for the second week of the Games.

The water quality of the Seine is highly influenced by rainfall in and around Paris. Heavy downpours, such as those seen during the opening ceremony of the Games, overwhelm the city's sewage system, leading to discharges of untreated effluent into the river.

Despite these challenges, organizers and World Triathlon are optimistic that water quality will improve in time for the competitions, based on the weather forecast for the next 48 hours. Following the rains on Friday and Saturday, sunny weather has returned to Paris since Sunday morning.

Due to an unusually wet spring and early summer, the Seine had been failing water tests until the start of July, with levels of E. Coli bacteria — an indicator of fecal contamination — sometimes exceeding authorized limits by tenfold.

Paris 2024 organizers have the option to delay outdoor swimming events by several days if necessary. As a last resort, they might cancel the swimming portion of the triathlon and relocate the marathon swimming event to Vaires-sur-Marne, a location on the Marne River east of Paris.

French authorities have invested 1.4 billion euros ($1.5 billion) over the past decade to clean up the Seine. On July 17, Paris Mayor Anne Hidalgo and Paris 2024 chief organizer Tony Estanguet swam in the Seine to demonstrate its readiness for the Olympics.