This is how Paris will clean up the Seine, 100 years after the bathing ban

Anyone who walks along the Saint Martin canal on a Sunday this summer can already see how well the promise is kept: a 100-meter section is open to swimmers. The news marks the end of an epic that began nearly a decade ago when Paris was chosen to host next year’s Olympics. The project foresees that some of the most emblematic events of the competition, such as the aquatic marathon and the triathlon, will take place in the river that crosses the City of Light.

Anyone who walks along the Saint Martin canal on a Sunday this summer can already see how well the promise is kept: a 100-meter section is open to swimmers. The news marks the end of an epic that began nearly a decade ago when Paris was chosen to host next year’s Olympics. The project anticipates that the news marks the end of an epic that began nearly a decade ago, when Paris was chosen to host next year’s Olympics. The project foresees that some of the most emblematic events of the competition, such as the aquatic marathon and the triathlon, will take place in the river that crosses the City of Light.

Anyone who walks along the Saint Martin canal on a Sunday this summer can already see how well the promise is kept: a 100-meter section is open to swimmers. The news marks the end of an epic that began nearly a decade ago when Paris was chosen to host next year’s Olympics. The project anticipates that the news marks the end of an epic that began nearly a decade ago, when Paris was chosen to host next year’s Olympics. The project foresees that some of the competition’s most emblematic events, such as the aquatic marathon and the triathlon, will take place in the river that crosses the City of Light. Those who walk along the Saint Martin canal on a Sunday this summer can already see that the promise is kept: a 100-meter stretch is open to swimmers. The news marks the end of an epic that began nearly a decade ago when Paris was chosen to host next year’s Olympics. The project anticipates that the news marks the end of an epic that began nearly a decade ago, when Paris was chosen to host next year’s Olympics. The project foresees that some of the most emblematic events of the competition, such as the aquatic marathon and the triathlon, will take place in the river that crosses the City of Light.

The three major challenges are the diversion of wastewater which continues to end up in the Seine, the improvement of the efficiency of the treatment plants and the limitation of pollution generated by river traffic, with the circulation of tourist boats and the transport of tourists and goods.

Pierre Rabadan, assistant adviser in charge of the Olympic Games and the Seine, stresses that the event will make it necessary to repair a “anomaly of industrialization which has led large cities to pollute their rivers, historically a source of life in urban areas.

“Very significant work has been carried out in the two largest wastewater treatment plants in the Paris region, so that the water discharged into the Seine is of better quality and has less bacteriological impact. And a second step is to readjust the pipes so that the wastewater can no longer be discharged into the Seine. “, Explain. “It is a stage that is still being completed, as it goes. In Paris, the 260 boats that cross the river will all be obliged, by 2024, to connect to the municipal sewerage network, which was technically not possible before, but which is today”.

Waste from ships is only a drop in the bucket compared to the waste water generated by some 30,000 homes whose pipes were not properly connected to treatment plants. Polluted water ends up in the Seine or the Marne, another major river in the Paris region.

The second major project is the construction of a huge underground reservoir in the Austerlitz district, east of the capital, to capture rainwater during heavy storms. The structure is 50 meters in diameter and 30 meters deep, with a maximum capacity of 46,000 cubic meters of water.

“When it rains, the water filters and ends up in the same place as the water used in toilets, sinks and showers. To prevent it from overflowing into the street, this mixture of wastewater and rainwater is dumped into the Seine. “, explains Samuel Colin Canivez, director of sanitation for the city. “With this work, we want to intercept the excess water, leave it in this reservoir until the storm passes and then send it for treatment before discharging it into the river”, he adds.

As the work progresses, at a total cost of 1,400 million euros, Paris is organizing specific events on the Seine to regain the trust of Parisians. A 2021 survey found that only 12% of residents would be willing to jump in and swim, which was common a century ago when locals splashed in the river.

Now, a convincing argument, 32 species of fish have returned to the Seine, 10 times more than in the 1980s.

Once the project is complete, the city council will periodically test the water for bacteria and fecal residue to ensure it remains suitable for swimming. This will be the main legacy of the Games for the city .

By 2025, three points on the Seine will be adapted to accommodate swimmers, in the west, in the center and in the east of the city.

Rabadan points out that the municipal government has not yet decided whether the river will be permanently open to visitors or whether swimming will only be allowed at certain times of the year, such as on hot days.

“Last summer, for example, the water was suitable for swimming 70% of the days, with satisfactory or excellent quality. And to give you an idea, last year, during the same days that the 2024 Olympic Games will be held, the water was suitable for swimming 92% of the days, ”specifies the municipal secretary. “Our commitment is that as long as the quality of the water allows it, according to European standards, the Seine will be open for swimming. ”.

The cleanup is also part of the capital’s long-term goals to prepare for more frequent higher temperatures due to climate change. Paris is expanding its green spaces and the river will be a refuge for the inhabitants of the city on hot days.

“In the climate evolution that we see, we will need more and more cool spaces in cities and the Seine will be one of them,” says Rabadan.

Although residents welcome the cleanup, environmental organizations warn that some aspects of the project could be hazardous to the environment. France Nature Environnement fears that peracetic acid, used for the chemical disinfection of water, will leak and be very toxic for the river ecosystem.

The body also warns that the city intends to eliminate potentially deadly bacteria like Escherichia coli, but has no plan to control chemical pollution generated by industries and agricultural production in the Paris region, which also end up in the Seine.