Paris mayor swims in Seine to show how clean the water is ahead of 2024 Olympics

LONDON -- Anne Hidalgo, the mayor of Paris, has swam in the Seine on Wednesday morning in a showcase of how clean the river is for the outdoor swimming events at the 2024 Paris Olympics which opens in just nine days.

The Seine’s water quality, however, remains questionable and has repeatedly failed tests in advance of the 33rd Olympiad.

"On the eve of the Games, when the Seine will play a key role, this event represents the demonstration of the efforts made by the city and the state to improve the quality of the Seine's waters and the ecological state of the river," Hidalgo's office said in a statement on Tuesday.

The Paris mayor entered the Seine at approximately 10 a.m. local time.

The 65-year-old mayor’s swim was reportedly postponed from last month when river samples were deemed to be too unhealthy for her to swim in.

She was accompanied by Tony Estanguet, a former Olympic canoeing champion who successfully led Paris's bid for the 2024 Summer Olympics and is serving as the head of the organizing committee, as well as the top security official for the greater Paris region, Marc Guillaume.

President Emmanuel Macron, who had promised to join them in a show of unity, was not there for the swim on Wednesday morning.

During heavy rains, sewage can overflow into the river. For example, on June 18, after several days of rain, E. coli levels in the Seine River jumped to roughly 10,000 Colony Forming Units per milliliter, more than 10 times the safety limit.

According to findings published by Paris City Hall earlier this month, the last week of June saw four days when the water was clean enough to swim in, according to European standards, but no days when it was clean enough to swim in according to U.S. standards.

Paris Olympics officials initially insisted there would be “no plan B,” but organizers revealed their contingency plans on July 5, saying that open-water swimming might take place in the Marne River instead. In addition, officials said they could delay the triathlon event or, in the worst-case scenario, eliminate the swimming portion of the competition altogether.

The Seine is set to be used for the swimming leg of the Olympics triathlon on July 30, 31 and August 5, as well as the open-water swimming on August 8 and 9.

ABC News' Joe Simonetti contributed to this report.