PARIS: Organizers of the Olympic and Paralympic Games in Paris can be forgiven for feeling a little queasy over their commitment to hold open water swimming in the spectacular but not quite yet pristine river Seine.

Last August, the swimming marathon test events were cancelled because the water was too dirty, as were the swimming legs on two of the four days of triathlon and para-triathlon tests.

The city of Paris has insisted "there is no plan B."

The course for the men's and women's 10-kilometer events will start at the iconic Pont Alexandre III bridge and, with the Invalides and Eiffel Tower in the background, head one kilometer down river past other famed attractions, including the Musee d'Orsay and the Grand Palais.

Perhaps appropriately, it passes the newly renovated Paris Sewer Museum before looping back. The triathlon swims are shorter and will turn back sooner.

It is a route chosen to showcase the beauty of Paris.

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

In 1990, when he was mayor before becoming French president, Jacques Chirac promised the river would "soon" be clean enough to swim in and that he would celebrate by taking a dip. He never did.

The current mayor, Anne Hidalgo, a vigorous promoter of green initiatives, has also promised she will take the plunge before the Olympics start and that the public will be allowed to swim at three locations by 2025.

City officials argue that the quality of the water has improved, but none of the samples collected between June and September 2023 met European standards on the minimum quality of water for swimming.

The big problem is fecal matter. The bacteria in the water increases sharply when heavy rain sweeps debris and untreated wastewater into the river from the banks and overflowing drains and sewers.

The city tests the water at 14 points. In 2022, water quality at three of them was judged to be "sufficient" but had deteriorated by last summer.