Emmanuel Macron, the French president, and Anne Hidalgo, Paris’s Socialist mayor, have both said they are willing to plunge into the Seine to show they are good sports before the event.
But Surfrider said its measurements had shown levels of two bacteria – E. coli and enterococci – were often double and sometimes three times higher than the maximum European permitted amounts. The bacteria indicates the presence of faecal matter.
“In health terms, [bathers] are exposed to illnesses such as gastro-enteritis, conjunctivitis, ear infections and skin problems,” Marc Valmassoni, campaign co-ordinator for the NGO, told France Info radio.
Olympics organisers and Paris authorities are banking on a major new storm water facility slated to be inaugurated later this month to help bring down pollution levels, while new sewage connections for river boats are continuing to be built.
They also point out the “alarming” pollution levels were recorded over the winter, one of the wettest in 30 years. Heavy rainfall is known to overwhelm Paris’s sewage system, leading to direct discharges of untreated effluent into the river.
Around €1.4 billion (£1.2 billion) has been spent upgrading sewage and storm water treatment facilities in the Paris region over the last decade to improve the quality of the Seine as well as its main tributary, the Marne.
Organisers have always maintained that the Olympic sport can only take place in the river if the weather is dry or the rainfall light.
But they have also consistently said there is no “plan B” for the events scheduled to take place in the river, to the dismay of competitors.
Cleaning up the Seine is intended to be one of the key legacy achievements of the Paris 2024 Olympics, with Ms Hidalgo promising to create three public bathing areas in the river next year.
