Launched in 2016 in anticipation of the Paris 2024 Olympic events, the "Plan Baignade" has considerably enhanced water quality in the Seine and Marne rivers. This plan now continues with the development of permanent swimming sites in Île-de-France, serving as cool havens for the public.
These new opportunities for swimming in open water address a triple objective: providing cool spaces amidst extreme heatwaves, ensuring safe swimming practices, and protecting water resources.
Improving the Île-de-France sanitation system is a major focus of the Plan Baignade. Water quality is assessed according to European standards, notably analyzing the presence of bacteria such as Escherichia Coli and Intestinal Enterococci, potential indicators of wastewater contamination. The plan aims to limit untreated wastewater discharges through network compliance, treatment plant upgrades, and boat connections.
Addressing non-compliant wastewater connections is a priority. Works have brought nearly 10,000 private connections into compliance between 2016 and 2024. Legislation has also introduced compliance certificates and increased penalties to ensure the proper condition of connections.
Connecting boats to the sanitation network is another key measure. Over 150 boats have been connected as part of the Paris 2024 Olympic and Paralympic Games, and the obligation now extends downstream of Paris.
Rain events remain a factor in water quality degradation, potentially leading to discharges via "storm overflows" in combined sewer systems or runoff in separate systems. Structures like the Austerlitz Basin in Paris aim to store rainwater to prevent network overload. Soil des-impermeabilization is also encouraged to limit runoff.
Practical guides, such as the one from the Atelier parisien d'urbanisme (APUR) and the Kit baignade, are available to assist project leaders in developing swimming sites, considering environmental constraints and other river uses.
