The French capital's Mayor Anne Hidalgo revealed the locations for swimming in the Seine, a key legacy ambition of the city hosting Olympic and Paralympic Games for the first time in 100 years.

The areas in the fourth, 15th, and 12th arrondissements, respectively, will be supervised by lifeguards and cordoned off by buoys to protect them from heavy boat traffic that carries cargo, garbage, and an estimated seven million tourists a year.

Pontoons will also be used to ensure safe access while changing areas and places to store belongings will be implemented on low docks.

It is aimed to be reminiscent of the 19th arrondissement's Bassin de la Villette where swimming has been possible since 2007 as part of Paris Plages, which itself began in 2002.

The Seine, one of world’s most iconic rivers stretching for 481 miles, from Burgundy through Paris out to the sea in Normandy, is due to play a central part at Paris 2024 as it is planned to host part of the Opening Ceremony, the marathon swim, and swimming elements of the triathlon. 

Authorities had banned swimming in the River Seine in 1923 because of high levels of pollution, a problem stretching back centuries to the 16th century when the bodies of those killed in religious wars between Protestants and Catholics were thrown into the water.

On average, 360 tons of large items, including television sets and motor cycles, is cleared from the River Seine each year, although the biggest source of pollution in modern times has been the dumping of countless tons of wastewater, both domestic and industrial sewage.

In 1988, a predecessor of Hidalgo's Jacques Chirac, who also served as French President, spoke of his ambition to make the Seine swimmable and the progress of his commitment is shown in these latest figures.

A recent survey found, however, that the amount of untreated wastewater that ended up in the River in 2022 was 90 per cent lower than 20 years ago.

"Historical data show that the quality of the Seine, which had deteriorated sharply until the 1980s, has improved considerably since the 1990s, under the effect of the renewal of the sewerage networks and the modernisation of the wastewater treatment plants," said microbiologist Françoise Lucas at the Paris-East Créteil University.

Deputy Mayor of Paris and former rugby union player Pierre Rabadan has claimed that France's first hosting of the Summer Games in 100 years has fast-tracked the project by at least 10 years in regard to investment.

A total of €1.4 billion (£1.2 billion/$1.5 billion) has been spent since 2016 to clean up the river, including installing wastewater collection networks for the 260 boats moored in Paris.

Of the 160 boats that are upstream of the Olympic events, which go as far as the Alexandre III Bridge, half are connected to the system with the rest set to join by the time the Games begin on July 26 next year.

A more difficult way to reduce waste into the river is poor connections to homes which are estimated to be the cause of nearly 80 per cent of bacteriological pollution of the Seine in inner Paris. 

Only a quarter of owners have complied to a system that sees their waste taken to a treatment plant instead of going into the river but city officials are planning to get at least 50 per cent on board by Games time.