Watch: Paris mayor swims in River Seine after sewage concerns ahead of Olympics

Watch as Paris mayor Anne Hidalgo swam in the River Seine on Wednesday, 17 July, as the city prepares to host the 2024 Olympics .

Organisers have invested €1.4bn ($1.5bn) to improve the cleanliness of the Seine for the Games and to ensure Parisians have a cleaner river in the years after it finishes.

However, a few spells of heavy rain could push E. coli levels beyond the limit of 900 colony-forming units per 100ml that the World Triathlon Federation has determined as safe for competitions.

Monitoring group Eau de Paris has tested the river water on a daily basis, yielding results that showed unsafe E. coli levels in recent weeks followed by results in early July that showed improvement.

Wednesday was a fulfilment of the promise Ms Hidalgo made in January, nine days before the opening ceremony, as part of a broader effort to showcase the river’s improved cleanliness.

The swim took place along the stretch of the river that passes by the Notre Dame Cathedral and City Hall.

Tony Estanguet, head of the Paris 2024 Games, and Marc Guillaume, the prefect of the Paris region, joined Ms Hidalgo.