The Seine River was poisoned for a hundred years. Its Olympic cleanup could change swimming around the world

In 2019, a few years before the Olympic athletes entered the Seine, a group of friends looked for a swimming pool in Metz, three hours east of Paris. The summer was getting very hot, and many municipal pools were closed or full. The group wanted to build a swimming pool on the Moselle River, which originates 125 kilometers from Metz in the Vosges mountains, and flows through the French city of about 117,000 people.

“It’s swimming most of the time,” said Sibylle van der Walt, who led the group. “It’s much better than the Seine.”

They founded Metz Ville d’Eau, a grassroots environmental organization, and partnered with university researchers to begin testing water quality in different areas along the river. Until now, bacterial levels have generally been protected except after heavy rains, including in the Canal de Jouy area, which had a river basin from 1934 until 1982. Full results are expected in May 2025, according to van der Walt.

Metz Ville d’Eau is part of the consortium of swimming cities, representing organizations from 31 cities in 16 countries that aim for clean and accessible urban streets. Last month, the coalition published a document setting out its goals and objectives—including establishing 30 swimming cities by 2030.

The group wants a “new status quo” for public access to city streets for swimming. Depending on the city and waterway, that may be as simple as allowing swimming in a previously polluted river where conditions have improved. Or it may require rewriting laws to allow filtered floating pools on rivers or to close waterways periodically for shipping, for example.

By creating a global umbrella for urban swimming initiatives, organizers say, they hope to encourage the exchange of ideas and prototypes. What works in New York or Paris or Metz can help direct efforts elsewhere.

“Instead of people trying to come up with similar solutions independently, can we collaborate with those that have already been developed?” said Matt Sykes, founder of Regeneration Projects, the Melbourne-based sustainability consultancy that started the coalition.

How the Seine went from toxic waste dump to ‘economic engine’

Plans for the first conference in Paris next summer are supported by the city’s deputy mayor. van der Walt hopes that this conference will encourage funding from cities or the European Union, to help more lakes, rivers and beaches to be introduced. But the transformation of the Seine for the Paris Olympics may finally be what brings unknown cities into the public eye and moves the projects forward.

Paris invested $1.5 billion in a stormwater storage tank, the equivalent of 20 Olympic-sized pools, to catch toxic water that would otherwise end up in the Seine. Three public swimming pools are scheduled to open next summer, including near the Eiffel Tower, where boats will be banned between 10 a.m. and 6 p.m.

“Government authorities can’t say, ‘Oh, it’s too complicated.’ We will not do this.’ If it’s done in Paris, you can do it in Toulouse,” said van der Walt, noting another French city struggling to get a swimming river.

Until this summer, swimming had been banned in the Seine since 1923. Like many urban rivers, it was a sink for raw sewage and toxic runoff (worldwide, more than 80% of unwashed wastewater returns to the environment). Tourist boats and commercial vessels have proliferated on the river, a route that takes 20 million tons of cargo each year.

All of that is changing, but not without a few hiccups. The men’s Olympic triathlon was postponed due to sewage overflows. Later it was reported that the Belgian athlete fell ill after swimming in the river, which led to his team abandoning the event.

While the Olympics may help “bring public attention to swimmable waterways,” the triathlon snafu also underscores that “for too long, we’ve treated our rivers like open sewers,” said Marc Yaggi, CEO of the Waterkeeper Alliance, a water policy advocacy group. they are clean. organization and member of the swimmable city alliance.

Benefits of urban swimming

Reversing those trends can go beyond restoring biodiversity (the Seine has more than 30 species of fish now, up from three in the 1970s). Clean waterways are essential to equitable cities, creating public spaces that support health, economic growth, and climate resilience. Swimming can be an “economic engine,” Yaggi said. “A swimming city can drive tourism and recreation and local business development. He has an environmental education forum, and a climate solution about giving people a place to cool off during the heat. “

Swimming will contribute almost £3 billion to social value in England by 2022, according to Swim England, a non-profit organization that promotes and promotes swimming in England, with benefits ranging from improved physical and mental health to reduced crime. London-based architect Chris Romer-Lee hopes to increase those benefits by creating swimming pools on the River Thames. His company, Studio Octopi, a member of the Bathing Cities Alliance, first proposed the Thames Baths in 2013.

A number of sites along the central London stretch of river have been considered, but “old rules about how the river is run” have thwarted each attempt, Romer-Lee said. The Port of London Authority (PLA) does not recommend swimming in the River Thames. And in addition to construction costs, the ponds will owe the PLA by using the detention facilities, which are lacking in the river. Those costs will put a lot of the public out of business “within a few years,” Romer-Lee said. “There needs to be flexibility in the way authorities deal with a not-for-profit public enterprise like Thames Baths.”

That seems more likely than last year, given London Mayor Sadiq Khan’s recent proposal for a swimming Thames by 2034. In addition, +Pool helped implement policy changes to promote filtered swimming pools in New York, providing a potential template for other major cities. Additionally, London recently completed its $6 billion Tideway Tunnel, a 600 Olympic-sized sewage overflow cup to keep it out of the Thames River. It won’t catch all the pollution from rivers that run into the river, but a “sponge city” approach that uses wetlands and green spaces “to collect water before it goes into the river” can help, Romer-Lee said.

Citizens fill in the blanks

In cities without money or political will, people often swim anyway, risking their lives by entering polluted rivers. Many areas rely on grassroots efforts to reduce, or at least raise awareness of, some of the risks. An open swim in the Milwaukee River highlighted the low water level there. Lake Ontario Waterkeeper created the Swimming Guide, an app that uses citizen science and government data to determine swimming at more than 10,000 locations. London Waterkeeper’s efforts have resulted in a real-time data map of sewage overflows by 2023.

Without that much information, “it’s not enough,” Yaggi said. “We know exactly how much carbon and methane are released into the atmosphere, but we don’t know what’s in our water, even though we have a lot of information about it.”

The cost of comprehensive water quality monitoring exceeds what state and local governments — and the U.S. government — are willing to invest, according to Yaggi. In addition, most water quality monitoring focuses on bacteriology—E. coli and Enterococcus—but van der Walt points out that the concentration of chemicals in the water and on the river bank may be negligible.

This summer, thanks to the advocacy of Metz Ville d’Eau, the mayor of Metz created a small sandy beach in the Moselle. But the river’s banks are contaminated with arsenic, according to chemical tests by Metz Ville d’Eau partners, which could put swimmers at risk if they use the new shallow swimming pool. In addition to the small sea, Van der Walt and his friends are still seeking the city’s permission for a filtered river dam in the deep Moselle. There will be opportunities to lean on the coalition for support, including a planned 2027 conference in Copenhagen to celebrate the 25th anniversary of Islands Brygge, the harbor’s bathing complex considered a model for urban swimming. Advertising about the Seine cleanup “could help us even more,” she said.

“It’s a new phase in the French scene,” added van der Walt. Just as cities built for cars see the need for pedestrian and bicycle lanes, he said, municipalities that put rivers first “are faced with the fact that there may be other water users.”