La Seine: The unpredictable star of the Paris Olympics

The River Seine was the fickle star of the Paris Olympics, taking centre stage at the opening ceremony and open water swimming and triathlon events despite a running saga over water quality.

It was under torrential rain that the Seine appeared before millions of viewers around the world on July 26 for a cheeky and controversial opening ceremony.

"Dantesque conditions," was how Games chief Tony Estanguet summed up the unprecedented Olympic opening ceremony, the first to take place outside the main stadium.

"Organising a ceremony on the Seine is not easier than doing it in a stadium... but it has more punch," Estanguet said.

"It is the spirit of Paris which has mingled with the Olympic spirit," said ceremony artistic director Thomas Jolly.

Winding its way through the centre of Paris, past famed attractions such as the Invalides, Place de la Concorde, and the Grand Palais, the river sparkled.

It was a route deliberately chosen to showcase the beauty of Paris.

It was also politically symbolic: swimming has been banned in the Seine since 1923 but various Paris mayors have vowed to clean it up.

But due to summer rains and storms, the water quality was not always up to standard.

Of 11 days of events and training scheduled in its murky waters, only five got the green light.

The river remained dogged by pollution problems despite a 1.4 billion euros ($1.5 billion) upgrade to improve the Paris sewerage and water treatment system.

Photos of triathletes diving from the Alexandre III bridge into the Seine will nevertheless remain some of the most iconic of the Paris Games.

"It was a bit chaotic," an organising committee source admitted to AFP.

Belgian Claire Michel fell sick after the women's triathlon, resulting in her team later withdrawing from the relay event, but it was not clear if her illness was linked to the Seine.

 'Seine cleaned up'   

During June, the water flow had increased to unexpected levels and remained two to three times higher than the usual summer level, contributing to the poor water quality.

For Paris mayor Anne Hidalgo, who promised Parisians they could take a dip next summer -- as she did the week before the Games -- "the Seine is cleaned up".

"I don't see the point in saying that it hasn't worked," she said.

But despite the clean-up effort, the Seine brought suspense to the build-up and was unsuitable for swimming for part of the Games.

"The elements were a little bit against us but we knew we would have to adapt," said Pierre Rabadan, a top Paris official.

"Despite everything, we competed in all the competitions with a quality of water which allowed us to deliver, without any risks to the athletes," he added.

But Parisians may have to wait to take a dip themselves.

Authorities face the ongoing problem of refreshing the city via a river that is being decontaminated but which climate change can contribute to polluting.

"Intense rain is one of the two meteorological faces of climate change, less known than rising temperatures," explained climate scientist Robert Vautard, a member of the intergovernmental panel on climate change (IPCC).

"We know that with an increase in global average temperature of one degree Celsius... the clouds are filled with more water vapour and therefore it rains more."