Seine still too dirty for swimming, two months before Paris Olympics

Triathletes dive into the Seine during a test event for the Olympics in Paris
During the Olympics in Paris, the Seine will host a leg of the triathlon and open-water swimming - BERTRAND GUAY/AFP

Water tests in the Seine in Paris have shown that the river is still too dirty to swim in, two months before the start of the Olympics, when it is set to be used by athletes, according to data from a charity released on Wednesday.

French authorities have been in a race against time to clean up the Seine, which will host the swimming leg of the triathlon at the end of July, as well as the open-water swimming in August.

Surfrider, a water charity, has been conducting regular tests to measure levels of two crucial bacteria that indicate the presence of faecal matter.

Its latest results showed levels of e-coli and enterococci higher than authorised limits set by sports federations and European bathing standards.

One reading for e-coli at the Alexandre III bridge was more than three times higher than the maximum level authorised by the triathlon and open-water swimming federations.

Heavy rainfall in May is likely to have contributed to what Surfrider called the “poor” water quality.

It noted that there had been heavy rain 36 hours before the tests, but only light rain in the previous 12 hours.

Heavy rainfall is known to overwhelm Paris’s sewage system, which is more than a century old, leading to direct discharges of untreated effluent into the river.

Organisers are praying for fine weather during the Olympics, which run from July 26 to Aug 11, and have been open about the possibility of needing to delay or even cancel the Seine swimming in the event of storms.

Although a new water-treatment plant in Champigny-sur-Marne, upstream of Paris, was inaugurated at the end of April, another major Olympics-related water infrastructure project has yet to enter service.

A giant new underground stormwater facility close to the Austerlitz train station in eastern Paris, that will stock water to prevent discharges into the river, is scheduled to come on stream in early June.

Cleaning up the Seine had been “probably the most difficult [Olympic] project to organise”, Emmanuel Gregoire, the deputy mayor of Paris, told reporters in April.

About 1.4 billion euros (£1.19 billion) has been spent by French authorities upgrading sewage treatment and stormwater facilities around Paris to reduce the amount of untreated faecal matter flowing into the river and its main tributary, the Marne.

The clean up has been promoted as one the key legacy achievements of Paris 2024, with Anne Hidalgo, the city’s mayor, intending to create three public bathing areas in the river next year.

She and Emmanuel Macron, the French president, have also promised to take a dip before the Games to demonstrate it is safe, with Ms Hidalgo pencilling in June 23 for her swim, according to sources.

Olympic open-water swimming has been hit by pollution concerns in the past, notably in Rio in 2016 and Tokyo in 2021.

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