Olympic swimming in the Seine? How Paris is recreating a river.

PARIS — An electric van sailed up the Seine, past the former palaces and elegant museums and under the low-slung stones and metal bridges before turning off at the Eiffel Tower and gliding down to the riverbank.

The captain, Arnaud Montand, traced the path planned for the opening ceremony of next summer’s Olympic Games and, on the final section of the route, the course for Olympic swimmers.

An important part of Paris’ winning bid was not to host events only on the river, but, remarkably, in It.

“What a beautiful view of Paris,” Montand said from behind the wheel in his cozy glass cabin, where he was protected from the pelting rain. “But when a storm comes, everything goes off track.”

For years, workers in Greater Paris have been implementing the so-called swimming plan – an engineer’s dream, with thousands of new underground pipes, tanks and pumps designed to prevent harmful bacteria from flowing into the Seine, especially during storms. If successful, the plan will produce a river clean enough for Olympians and later civilians to swim in.

“Do we have a 100 percent guarantee? The answer is no,” said Pierre Rabadan, the deputy mayor who is spearheading the city’s Olympic plans, including cleaning up the Seine in time for two long-distance races and the swimming stages of the triathlon. “If it rains incessantly for a week before the races, we know that the water quality – even with all the work that has been done – probably won’t be excellent.”

But Rabadan also said there was no alternative plan: if the races have to be postponed, the organizers will simply wait a few days, test the water quality and try again.

Liquid landmark

Considered by many to be the most romantic river in the world, the Seine is also smelly, murky and – after big Saturday nights – lined with the dirty remains of revelers. During massive downpours, 40 portholes scattered across the cobbled banks of the river gush with sewage.

That’s why many Parisians – even some who work on the official swimming plan – are horrified at the idea of ​​diving into the river.

“Have you seen the Seine?” said Michael Rodrigues deep in a hole in a sidewalk, where he was connecting a new pipe to a house so no more sewage would seep into the river. “I am not interested.”

That was not always the case. During the first Olympic Games hosted by Paris, in 1900, seven swimming events were held in the river. Even after swimming in the water was banned in 1923, a year before the Games returned to the city, locals continued to dive off the Pont d’Iéna on hot summer days, with the Eiffel Tower rising behind them as they cooled off in the water.

But the river became increasingly polluted with sewage and industrial waste. A study in the 1990s classified the piece that runs through Paris as one of the highest levels of heavy metal in the world, according to a history of the river.

Promises to return to those swimming days were made by Jacques Chirac, a former mayor of Paris and later president of France, who swore in 1990 that three years from now he will swim in the Seine in front of witnesses to prove that the Seine a clean river.”

That never happened.

“They were just nice words,” said Jean-Marie Mouchel, a hydrologist and professor at Sorbonne University who has studied the Seine for three decades. While many improvements have been made to the river’s water quality, particularly through the modernization of sewage treatment plants, “there was no plan for swimming in the Seine before 2020,” he said.

The Olympics changed that – not just by pushing the plan, but by inspiring a budget of 1.4 billion euros (more than $1.53 billion) to implement it.

A legacy of the Games, as promised by the city’s mayor, Anne Hidalgo, will give locals access to some 20 swimming areas along the Seine and its upstream tributary, the Marne, by summer 2025.

“The Games were just an accelerator for the transformation and improvement of water quality,” said Rabadan, adding that the plan had brought together more than 20 government, water and sanitation, as well as river and port authorities, who otherwise “probably wouldn’t.” have committed.”

Blowjob and conviction

The aim of each agency involved is to clean the water so that the levels of two indicator bacteria – E. coli and intestinal enterococci – are below the standards set by the European Bathing Directive. Olympic standards allow slightly higher levels, subject to committee approval.

Teams in France have been regularly testing the waters of the Seine since 2020. Last summer, about half of their samples met the target. But those were taken over a long stretch of the river and its tributary over three summer months.

When workers tested the course of the planned Olympic events — the swim portion of the triathlon and two 10-kilometer events for men and women — over two weeks in the late summer, when the Olympics will take place, the results were 90 percent “fair, meaning an Olympic committee would have to decide if it goes ahead.

Rabadan and other city officials saw that as promising, as most of the Swimming Plan has yet to be implemented.

“We are not purifying the Seine,” said Samuel Colin-Canivez, the city’s chief engineer in charge of sewerage projects, as he led a tour of a newly built tunnel that extends under the river. “Our approach is to prevent untreated water from being dumped into the Seine.”

The 700-metre long tunnel connects to a huge underground storage tank under construction between Austerlitz train station and a 350 year old hospital. Together they will have room to hold 13.2 million gallons – enough water to fill 20 Olympic swimming pools.

The tunnel and tank are among five major engineering projects being built to deal with storms that are now overwhelming Paris’s ancient sewer system, and more importantly, to drain both sewage and rainwater. When those tunnels are flooded by rainwater, they discharge everything – rain, sink and toilet water – into the Seine.

“Right now that happens 12 times a year when it rains heavily in the eastern part of the city,” Colin-Canivez said as he walked around the partially built tank. Once completed, the giant reservoir will hold that water during storms and then slowly release it back into the sewage system after the rains stop. “Our goal with this is to reduce that to two times.”

That is the rain-weather strategy to keep sewage water out of the Seine. The dry weather strategy includes another series of projects. Some are simple, such as adding special treatments to two upstream sewage treatment plants. The bigger plant, Seine-Valenton, absorbs the wastewater of 2.5 million people, ten kilometers southwest of Paris. Once small amounts of performic acid are put down the drain in June, levels of harmful fecal bacteria will be reduced a hundredfold, said Vincent Rocher, director of innovation at the Greater Paris Sanitation Authority.

Others are smaller and more personal, like the teams going door-to-door in six Paris suburbs trying to persuade more than 20,000 homeowners to allow workers to dig up their pipes and reconnect them to the sewers . For example, it is believed that many houses discharge their waste water into the Seine or Marne.

“House by house,” says Claire Costel, who leads the project in the region just southeast of Paris. “There’s no other way to do it.”

Here there are two separate underground systems of tunnels: one just for sewage and another reserved for rainwater. In many cases, however, builders have connected sewer pipes to the stormwater system. In others, such as on the small island of Fanac, houses were built to discharge their wastewater directly into the Marne.

The only way to find out which homes have bad connections, Costel said, is to check their plumbing. Then her team tries to persuade the homeowners to allow them to fix the mistake.

While the teams can offer $6,000 grants that often cover renovation costs, many homeowners refuse. By March, only about 5,000 had accepted, according to a city report.

“It’s delicate,” Costel explained. “We can’t force them to open their doors.”

Her team has been the most successful, installing a new sewerage and pumping system for the 40 houses on Fanac.

The selling point for many residents, on Fanac and in nearby towns, was its Olympic legacy.

“I learned to swim in the Marne as a child,” says 70-year-old Jean-Louis Bourgeois, who stood outside his brick house in Le Perreux-sur-Marne one morning after workers worked to complete his sewage system. “I would be very happy to swim there again.”

Surface tension

Within the city limits of Paris, the workers focus not on houses, but on boats. Some 170 are moored along the banks of the Seine upstream from the Olympic sites. Until recently, almost all of them discharged their waste water directly into the river.

In 2018, the city declared that all boats must be connected to the city’s sewage system, and the port authority began the costly process of installing sewage hookups and pumps in those ports that did not have them. Water residents were given two years to install connected wastewater collection systems in their boats.

To date, only about half have done the job, according to city officials.

Many boat owners have complained about being unfairly targeted. Unlike their terrestrial neighbours, they were not given a choice, and retrofitting old boats can cost as much as $25,000 – five times what the government offers in subsidies.

“Do you think the boat park 30 kilometers from Paris will be connected to a waste water system?” said Hervé Lavollée, who lives on a retrofitted 1937 barge moored near a pedestrian bridge in the heart of Paris. “They’re all making a fuss about this before the 8 p.m. news, so it looks like they’re doing a lot, but it’s ridiculous.”

Nicolas Londinsky, the director of water and sewage systems in Paris, acknowledges that the pollution from the boats is relatively small, but says it could make the difference between a successful water quality test at a nearby swimming area and a failed test. “If we really want to improve water quality, we have to do everything we can,” he said.

And despite his criticism, Lavollée said he liked the idea of ​​swimming in the Seine. Every night, while brushing his teeth in his boat’s bathroom, he looks out over the river, twinkling under the lights of the city.

He is constantly amazed by its beauty.

“If we get the chance to show the world what the Seine is, and offer this view of Paris,” he said, “it’s a great idea.”