Will the River Seine be clean enough to swim in at Paris 2024 Games?

The River Seine will be a central element of the Paris 2024 Olympics, with the opening ceremony taking place on the river with a boat parade and two events, the marathon swimming and the swimming leg of the triathlon scheduled to be held there.

However, pollution levels in the Seine have raised health concerns for athletes.

WHERE DO WE STAND NOW?

The monitoring group (State and City of Paris), based on Eau de Paris water analysis, publishes weekly results. The latest data published on 12 July showed water quality would be suitable for swimming in six out of seven days at the Olympics swimming sites.

WHAT ARE THE CONDITIONS FOR THE RIVER TO BE SUITABLE FOR SWIMMING?

Testers measure the level of two bacteria - E. coli (Escherichia coli) and Enterococcus faecalis.

According to European standards, the safe limit for E. coli is 900 colony-forming units (cfu) per 100 millilitres while the threshold for Enterococcus is 330 cfu/100ml.

WHICH FACTORS INFLUENCE THE WATER QUALITY?

According to Benjamin Raigneau, Director of Water Quality at the Paris city hall, four main factors have an impact on water pollution.
- Rainfall. More rain more pollution runoff.
- UV index. "The higher the UV index, the faster the bacteria die," said Raigneau.
- Temperature. The higher the temperature, the faster the bacteria dies. "Whether the temperature of the water is 16 degrees Celsius (60 Fahrenheit), or above 22 Celsius (71 Fahrenheit) like it usually is in the summer, it makes a significant difference," said Raigneau.
- The flow of the river. The faster the flow the higher the pollution.

WHAT HAS BEEN DONE TO IMPROVE THE QUALITY OF THE WATER?

The city of Paris built a storage basin capable of holding 46,000 cubic metres of waste water to