Parisians rushed for a dip in the Seine on Saturday as authorities opened the river to public swimming for the first time since 1923 after an extensive clean-up operation spurred on by it being used last year as a venue in the Paris Olympics.

Three sites along the banks of the Seine in the city will be able to welcome over 1,000 swimmers daily until August 31, local officials said, to the delight of the Parisians and visitors who were among the first to take the plunge.

“Really nice, I’m impressed, surprised,” said 24-year-old Victoria Cnop, a Brazilian who lives in Paris. “I never imagined being in the water close to the Eiffel Tower.”

“The water is clean, it’s warm, it’s clear. There is a bit of algae, but that’s normal,” said 51-year-old Karine. “Come here everybody, it’s great!.”

The reopening of the Seine for public swimming follows efforts by authorities to improve its water quality so it could be used for Olympic events last summer.

Investments included connecting tens of thousands of homes to the sewer system, upgrading water treatment facilities and constructing large rainwater storage reservoirs to prevent sewer overflow during heavy storms.

While delays, triggered by the health impact of heavy rains, impacted some Olympic training sessions and the men’s triathlon event, competitions in the Seine eventually went ahead, bolstering confidence in the river’s safety for public swimming.

Daily water quality tests will be conducted during the swimming season, with green and red flags — similar to beach safety systems — indicating whether swimming areas are open or closed.

“It’s wonderful,” said John Drummond, a 54-year-old visitor from Canada. “It’s great for the environment, it’s great for the city, it’s great for the people that live here. So very good initiative.”

As well as the three sites within Paris, 14 swimming areas outside the capital’s boundaries will be set up on the Seine and the Marne rivers. Two of those already opened on the Marne in June.