Faced with this scenario of uncertainty, the Organising Committee just presented a Plan B in case the hydrographic conditions remain unfavorable when the scheduled date for these competitions arrives. While it is true that there has not been abundant rain in these recent days and, therefore, the levels of bacteria such as Escherichia coli in the Seine are acceptable for human bathing, caution is warranted.

The Organising Committee is clear that these sports disciplines cannot be left to the mercy of the weather, so an alternative proposal has been designed to allow the Olympic schedule to proceed in case swimming in the Seine is ultimately deemed unhealthy. "The possibility of atypical weather events requires us to be cautious."

Initially, the organizers have confirmed through a statement that the triathlon and marathon swimming, scheduled to take place near the Pont Alexandre III between July 30 and August 5, could be postponed for a few days if conditions are not entirely safe. In addition to this, if heavy rain affects the flow of the Seine and increases its bacterial levels, there is the option to convert the triathlon into a duathlon by eliminating the swimming leg. "As a last resort, the regulations provide for this possibility," assures Tony Estanguet, president of the Committee.

As for the open water marathon, this event could be relocated to the Vaires-sur-Marne Nautical Stadium, located in the metropolitan area of Paris, which already hosts rowing and canoeing events and has a capacity designed to accommodate up to 15,000 spectators.

Updated data from analyses on the water quality of the Seine River indicate a significant improvement in bacterial indices in recent days. The City Hall of Paris and the Prefecture of the Ile de France Region highlighted in their weekly bulletin published this Thursday that water quality "has improved" in the last period examined, specifically from 24 June to 2 July.

Thus, if this trend continues with the improvement of bacteriological thresholds, the Seine River will be able to host the two sports events initially scheduled in the Olympic calendar: the triathlon (men's event on July 30, women's event on July 31, and mixed relays on August 5) and open water swimming (women's 10 kilometers on August 8 and men's 10 kilometers on August 9).

Administrations have invested 1.4 billion euros since 2016 in an ambitious plan to allow swimming in the waters of the Seine, where it has not been authorised for nearly a century due to health reasons. These interventions, which have included the construction of giant reservoirs, aim above all to prevent sewage water from going into the river and contaminating it, without passing through treatment plants during periods of heavy precipitation.