Is the Seine River safe for Olympic swimming?

Some laugh out loud, others raise their eyebrows or make faces. On the stone quays of the Seine, even the most passionate odes to the charms of the river tend to reach the same conclusion: no.

“Swim in it? Me?” said pensioner Patrice Desrousses, 64, stepping back slightly as he paused on his walk along the historic canal. “Oh, I don’t think so.”

Less than two weeks before Paris opens its first Olympic Games in a century, the Seine — aquatic muse of poets and painters, backdrop to the city's most majestic monuments, yearned for by generations of lovers — remains the designated outdoor venue for marathon swimming and triathlon events during the world sporting festival.

Although no one knows if this will actually happen.

Recent water quality tests have shown steady improvement and if current trends continue, the river could be considered safe for swimming. But readings taken earlier this summer revealed high levels of E. coli bacteria, indicating the presence of fecal matter.

Despite a costly and ambitious anti-pollution initiative, officials acknowledge that a single torrential downpour at an inopportune time could send a surge of sewage into the canal.

For visitors and locals alike, the ongoing drama over whether the Seine will be swimmable has become a spectator sport in itself.

“Our dream was to bathe in the river like Parisians did 100 years ago,” the city's mayor, Anne Hidalgo, said in May at the inauguration of a massive stormwater cistern near the Austerlitz train station, one of a half-dozen major infrastructure projects in a $1.5 billion campaign to clean up the river.

Hidalgo has promised to swim the Seine this week as a show of confidence in her Olympic preparation, although she has not followed through on her June promise to do so. France's sports minister, Amelie Oudea-Castera, took the plunge this month, although some spectators noted that she did not stay in the water for long.

French President Emmanuel Macron — fresh from a close election in which his centrists and a left-wing group beat back a far-right challenge but ended in a parliamentary deadlock — promised months ago to swim in the river before the Olympics, but then, joking or not, told reporters he wouldn’t say when, because then they would turn up to watch.

To further discourage high-profile plans to take a dip, online activists, unleashing an abundance of scatological puns, last month threatened to defecate in the river en masse as an expression of frustration with politicians over pressing social issues.

Although forecasters say the forecast between now and the start of the Games is for warm, sunny weather that will help keep waterborne bacteria levels low, the Olympic organising committee has confirmed there are back-up plans in place should the Seine be deemed unsuitable for competitive swimming, which, as many commentators have pointed out, involves open-mouthed gasping for air.

Among the emergency measures are postponing events now scheduled between July 30 and August 5; changing the triathlon to a duathlon by removing the swimming element; or relocating the marathon swimming event to a nautical stadium about an hour and a half away by car in Vaires-sur-Marne, which is already set to host rowing and canoeing competitions.

By design, there has been little talk of alternative plans and organisers have expressed positivity almost daily, but official optimism is often at odds with the opinions of passersby.

“How beautiful! How romantic! And how dirty!” said runner Jeff Sanchez, 54, as he paused near the ornate Pont Alexandre III, which overlooks one of the competition venues. He predicted that contingency plans would need to be activated rather than risk swimmers’ health.

A lanky young skater, who declined to give his name, smiled and shook himself all over like a dog after a bath when asked if he thought Olympic swimmers would be able to cross the Seine.

For more than a century, swimming in the river was banned – although, as Sorbonne University environmental historian Laurence Lestel explained to the BBC this year, the ban was originally imposed because of the dangers to navigation, not pollution. But back then the river was really dirty: at the 1900 Paris Olympics, she said, the swimming events were held “just upstream of a sewage discharge point”.

Since the Middle Ages, Paris's early underground waste channels have been a source of public fascination and a source of plague, crime and existential dread.

A tourist boat sails along the Seine River, with grandstands for spectators set up on its banks, on July 4, near Notre Dame Cathedral in Paris.

(Thibault Camus / Associated Press)

In the mid-19th century, Georges-Eugène Haussmann (prefect of the Seine under Napoleon III) helped introduce the city's modern sewer system as part of a massive redevelopment effort that included the leveling of thousands of old structures to make way for Paris's characteristic expanse of wide boulevards.

“The sewer is the conscience of the city,” wrote the poet and novelist Victor Hugo, famous for his Les Misérables. “There everything converges and clashes with everything else.”

Much of that 19th-century system survives, in updated form, its vulnerability to flooding only partly countered by the pre-Olympic clean-up spree.

In the cold, echoing caverns of Paris’s underground Sewer Museum — where the familiar blue street signs in the tunnels accurately mirror those above — a voiceover on a video extolling high-tech improvements ruefully informs visitors that under certain circumstances, untreated sewage still sometimes makes its way into the Seine.

Visitors were diplomatic about how clean the river could be for the Games.

“It’s clear they’re trying really hard,” said Canadian commercial pilot Brian Beare, 47, as he walked the museum’s stone halls in early July with his wife and two young children. “But you see these kinds of runoff issues in any big city, like Toronto and Lake Ontario. You just have to keep working on it.”

Meanwhile, an elaborate network of stands and scaffolding is being built on the riverbanks in preparation for the opening ceremony: a grand parade of boats from east to west through the centre of Paris.

Day and night, the city's bridges are filled with a torrent of tongues. The wide wakes of tourist boats lap against the quays. Visitors stroll along the riverbank. bookmakersthe dark green bookstands that Macron personally made sure remained in place during the Olympics despite security concerns.

As dawn and dusk fall, the play of light and shadow turns the river green or lead grey, a lustrous pearly colour or a mottled brown.

“There are a lot of things that people are worried about these days. We hope that the Olympics will be safe for everyone, including swimmers,” said Marie-Helene Marin, a shop assistant in her sixties and a lifelong Parisian who was walking her wrinkled-faced pug a few blocks from the river. “But when this is all over, whatever happens, it will still be our Seine.”