Paris’s River Seine remains dangerously polluted for swimmers as Summer Olympics approach

There are still 28 days to go until the opening ceremony of the Summer Olympics, and tests conducted in the historic Seine River show that the water is still at dangerous levels of contamination with E. coli, which is often associated with fecal bacteria.

The test, conducted by the Paris Water Monitoring Group of the city mayor’s office, showed that pollution levels in four different areas were above the safe limit of 900 colony-forming units per 100 millilitres, the limit set by the World Triathlon Union.

In addition to the triathlon events, marathon swimmers are scheduled to dive into the river to participate in their events. The three triathlon events will be held from July 30 to August 5, while the marathon swimming races will be held on August 8 and 9.

E. coli bacteria, along with intestinal bacteria, can cause diarrhea, urinary tract infections, pneumonia, and blood poisoning when ingested. The latest results mark the third week in a row that samples taken from the river contained unsafe levels of faecal-associated bacteria.

A “good water quality” rating is less than 500 colony-forming units of E. coli per 100 milliliters of water and less than 200 colony-forming units of enterococci.

It has been illegal to swim in the river since 1923. Paris spent $1.5 billion to build a water reservoir and a network of underground sewers and treatment plants to capture sewage during rainstorms that normally flows into the river.

However, the recent heavy rains — which were also responsible for wreaking havoc at the French Open — have washed more sewage into the waterway. In April, Paris 2024 president Tony Estanguet told CBS that the Olympics could be postponed if the rains continue into the Games.

Summer weather should help with cleanup efforts, as the dry period and summer sun will help kill some of the bacteria.

Previously, organizers said there was no backup plan or venue in case the rain continued. One option would be to turn the triathlon into a duathlon consisting of just cycling and running.

French President Emmanuel Macron and Paris Mayor Anne Hidalgo continued to say that their decade-long efforts would get the picturesque river ready in time for the events. Both said they planned to swim in the river themselves to prove its cleanliness.

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(Photo: Miguel Medina/AFP/Getty Images)