Has bathing in the Seine become a possibility with the construction of the Austerlitz basin?

Vrai / Faux
Updated on 15/05/2024
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Will swimming be possible all year round? How much did it cost? Why is the structure made of concrete? What other measures are underway to improve water quality in the Seine and its tributary, the Marne? We answer these questions

The Austerlitz basin (Bassin d'Austerlitz) will prevent wastewater from being discharged into the Seine


The new Austerlitz basin (50,000 cubic meters in volume) will prevent wastewater from being discharged into the Seine during heavy rainfall. This excess water will then flow progressively into the sewage system, where it will be treated in a wastewater treatment plant.
Thanks to the Austerlitz basin, the overflow gates will now be open for the heaviest rainfall, i.e. on average twice a year, compared with ten to fifteen times at present. This will allow for more bathing opportunities.

Construction of the basin cost 90 million euros (not 1.4 billion).


Construction of the basin cost around 90 million euros. It was financed by the City of Paris, the French State, the Agence de l'eau Seine-Normandie (AESN) and the Syndicat interdépartemental pour l'assainissement de l'agglomération parisienne (SIAAP). These institutions and numerous other financial backers have invested around 1.4 billion euros into the bathing plan that will enable the public to take to the Seine in 2025.
These investments were primarily short-term actions to improve the water network structure. The aim is to improve wastewater storage capacity and flow management. Disconnecting the rainwater network from the main system during construction work is one of the long-term aims of this investment.
Three other major wastewater treatment facilities have been created as part of the bathing plan: the Ru Saint-Baudile catchment area (Seine-Saint-Denis), the VL8 (a 10-kilometer long high-capacity collector between Essonne and Val-de-Marne) and the Val-de-Marne rainwater treatment plant.

Swimming in the Seine will be possible after the Paris 2024 Games


The opening of three inner-city bathing areas is scheduled for summer 2025.
In the Île-de-France region, 32 sites could be turned into potential bathing spots in the Seine and Marne rivers over the next few years.

Swimming will be possible all year round


Water quality varies throughout the year. Bathing in the river will only be possible over the summer months due to specific meteorological conditions that impact bacteria levels found in the water. The river is a natural environment that is highly reactive to weather conditions, as well as to sanitation-related incidents.

Water quality in the Seine continues to improve


Year after year, the environmental quality of the Seine improves. Since 2019, when the city launched its summer quality control campaigns, the bath-ability threshold has regularly been met. This threshold is strictly regulated by a European directive on bathing water quality management. It sets a threshold for bacteria levels, and targets two of them: Escherichia coli(E. coli) and Enterococcus.
These efforts have improved the river's ecological status. More than thirty species of fish can now be found in the Seine, compared with just three forty years ago.
Discharges can also come from barges and floating buildings that are not connected to the Paris sewage system and discharge their wastewater directly into the Seine. This will no longer be the case this summer, when all barges will be connected up to the network.

The Austerlitz basin is made of concrete, but more sustainable alternatives were possible


Erecting such a structure without using concrete is impossible. The pool is 34 metres deep and it's foundations are embedded 80 metres into the ground. Bio-sourced, alternative and sustainable materials, which are rapidly gaining ground in the building industry, could not be used for such a structure.

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