Swimmers set to return to the Seine

France's capital expects swimmers to return to its iconic but polluted River Seine before next year's Olympic Games — with a cleanup making it possible for scenes to be recreated that have not been seen for 100 years.

The cleanup, which aims to rid the river of harmful bacteria, will cost 1.4 billion euros ($1.5 billion) by the time it is complete.

Pierre Rabadan, a deputy mayor of Paris, told The Times newspaper the municipality started work on the cleanup back in 2017 — after it heard it would be hosting the Olympics.

"We will have taken seven years to do what would have taken 30 or 40 years if we had not organized the Olympic and Paralympics," Rabadan told the paper.

"This is a landmark event, the beginning of the re-conquest of the Seine."

The river had been popular with swimmers in the French capital throughout history and appears in many iconic old paintings but became unusable because of increasing levels of sewage and other pollutants, meaning access to it was prohibited in 1923.

Now, 100 years later, the municipality is planning to not only purify the river but create four floating "beaches "in the city center, with the first set to open close to the Notre Dame cathedral.

The cleanup drive meant 35,000 properties close to the river needed to be connected to the mains sewer system. Additionally, the owners of houseboats and barges have been prohibited from discharging sewage into the river.

Rainwater that used to run into the city's sewage system and that frequently caused it to reach capacity and overflow into the river is now channeled directly into a huge underground reservoir from which it is processed. Paris has also built several new sewage treatment plants that are purifying water that used to run into the river untreated, meaning fish have returned to the Seine.

Around 15 riverside suburban towns outside the capital have also joined in the cleanup initiative, and are also planning to create swimming areas along their stretches of the Seine.

Jean-Marie Mouchel, a hydrology professor at the Sorbonne, told The Times the cleanup efforts have already improved the river massively but the amount of fecal bacteria still needs to be lowered further before swimmers can safely return to the river. Mouchel said that should be achieved by next summer.

Whether Parisians will return to swimming in the Seine is another matter. An Ifop poll conducted in 2021 found only 12 percent were open to the idea of taking to the capital's murky and long-outlawed waters.