Heavy rain sparks concerns over Olympic swimming - as Seine fails water quality test days before events

Heavy rain during the Olympics opening ceremony raised concerns over whether the River Seine will be clean enough to host swimming competitions, with test results released on Friday showing the water quality was slightly above the required level before Paris 2024 started.

The River Seine will be used to host marathon swimming and triathlon events and Paris Mayor Anne Hidalgo took a dip last week in a bid to ease fears amid worries over pollution levels. Around €1.5bn has been spent since 2015 in a bid to clean the river, where swimming has been banned to the public for over a century.

Tests by monitoring group Eau de Paris showed that E. coli levels were above the safe limit of when mayor Hidalgo took a dip, in a long-standing vow before the Games.

Water quality is linked to the weather and heavy downpours in Paris during Friday night’s opening ceremony is a headache to Games organisers just days before the open-water swimming events begin, as E. coli levels are measured daily.

“The rain that has fallen on Paris over the last 24 hours is likely to impact the quality of the water in the Seine over the next 24 to 36 hours,” organisers said in a statement to Reuters.

“Depending on current water quality levels and the conditions expected over the next 24 hours, it is possible that the familiarisation [athlete training] may be cancelled.”

A decision will reportedly be made on whether the training will go ahead at 3am BST on Sunday, and the weather forecast is due to improve.

Paris City Hall noted that water quality last week was in line with European rules in six days out of seven.

In explaining the results, it said that "the flow of the Seine is highly unstable due to regular rainfall episodes and remains more than twice the usual flow in summer.”