By John Q. Hosedrinker 
On July 5, 2025, the Seine River in Paris opened its three swimming pools for the ‘Paris Plages’ event. This marked the beginning of the Pont Marie safe bathing site, welcoming swimmers to enjoy the water. People were observed swimming and diving, taking advantage of the recreational opportunity. This event offered a public space for Parisians and visitors alike to cool off and enjoy the river.
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Paris shuts Seine swim spots, a headline that’s certainly a mouthful, but one that unfortunately paints a rather stinky picture. The City Hall website confirmed that three swimming spots along the Seine were temporarily closed due to rainfall. The timing was particularly unfortunate, as this happened just one day after the river had been reopened to bathers for the first time in a century.
The root of the problem, and the reason for the swift shutdown, lies in the city’s aging infrastructure. Paris, like many older cities, has a sewage system designed back in the mid-19th century. On rainy days, this system is often overwhelmed. This leads to an overflow, meaning rainwater and wastewater mix and pour directly into the Seine. It’s a case of “out of sight, out of mind” not being an option when you’re considering a swim.
And let’s be honest, it’s a bit gross, isn’t it? Especially considering the image of swimmers in the Seine on the opening day. While the city has made efforts to clean up the river, and it has been an important point for triathletes and other athletes, it’s a tale as old as time: rain and sewage don’t make for a pleasant (or safe) swimming experience. Many places advise against swimming in rivers, especially after heavy rainfall, until harmful bacteria levels can be properly assessed and have time to settle.
The closure isn’t necessarily a reflection of a lack of effort. It’s a pretty standard consequence of how many urban sewer systems are designed. Most cities, whether in the US, Canada, or even Tokyo, face similar challenges. Even with modern infrastructure, it’s tough to build a system capable of handling torrential downpours without overflow. And the renovations that have been done in Paris are designed to address this, but the sheer volume of water that can come down during a major storm remains a significant hurdle.
It’s important to remember that rain washes all sorts of unsavory stuff into waterways. It’s not just sewage. Think about runoff from roads, containing things like car fluids, dirt, and whatever else gets swept along. So, even if there wasn’t a sewage overflow, the water quality would still likely be compromised after a good rain.
This situation shouldn’t be a surprise to anyone. The combination of aging infrastructure and heavy rainfall is a recipe for these types of closures. It’s a frustrating reminder that even with grand plans and significant investments, there are limitations to what can be achieved. And the solution isn’t as simple as building a new sewer system overnight, as it requires a substantial amount of money and time to undertake such a massive project in a built up city.
In the meantime, it appears that the anglers know what they’re doing. They often act as a way of monitoring water quality by watching how the fish and other water life thrive. And they might be some of the first to realize the dangers of the river during the rain. And as has been suggested, Paris, like Chicago with its reservoir plan, could use existing infrastructure, such as old mines and quarries, to create huge water reservoirs that fill up with the run-off from rainfall, treat the water and use it. This is the way it’s done in many places around the world.
Ultimately, while the reopening of the Seine to swimmers was a historic moment, it’s also a reminder that the complexities of urban infrastructure require ongoing attention and investment.