A water charity said Monday that tests of water from the Seine river, where water events are set to take place in less than four months during the Paris 2024 Summer Olympic and Paralympic Games, showed alarming levels of bacteria including E.coli.

A “shadow looms over the quality of the water in the Seine River,” the Surfrider Foundation Europe said in a social media post. The group said it performed 14 tests on different samples taken from two spots along the Seine from September 2023 to March 2024, and that all but one of the results showed poor water quality.

The samples “reveal alarming levels of bacteriological pollution at the Alexandre III Bridge,” the spot it said would be the starting point for Olympic and Paralympic triathlon and marathon swimming events. 

“There are many causes for this pollution, ranging from rainfall to malfunctions in the sewage system, including poorly connected barges and animal waste,” Surfrider said.

The group urged stakeholders to take action in the time remaining ahead of the games, which kick off on July 26.

“The consequences of this pollution on health are serious, ranging from common infections such as otitis and conjunctivitis to more severe infections such as staphylococcus,” the organization said. “It’s also an opportunity to reaffirm how precious health is in all circumstances, but especially when you are an athlete pursuing such a big dream: That of becoming an Olympic champion.”

Paris Mayor Anne Hidalgo has said she intends to create three public bathing areas in the Seine next year, and has made cleaning up the river one of the key legacy achievements of the Paris Olympics, French news agency AFP reported. About $1.5 billion has been spent upgrading storm water treatment and sewage facilities already, AFP said.

“The first quarter of 2024 saw extremely large rainfall (250,000 ml over three months, double the level of 2023) which deteriorated the quality of the water,” the Paris prefect’s office said in a statement to AFP, adding that water disinfection facilities had not been operating over the winter and would be started ahead of the games.

“There has never been question of opening the Seine for swimming all year round,” Marc Guillaume, the top state security official for Paris, told the news agency.

Water quality has been an issue at other Olympic Games, including the 2020 Tokyo Olympics and the 2016 Rio Olympics.