Olympics - River Seine suitable for swimming six out of seven days from July 17-23

Data published by the city and regional authorities showed the concentrations of enterococci and E.coli bacteria were above legal thresholds on July 21.

The French capital has been working on cleaning up the Seine so people can swim in it again, as was the case during the 1900 Paris Olympics. But a sewer problem last summer led to the cancellation of a pre-Olympics swimming event.

The triathlon and marathon swimming legs of the Olympics, which run from July 26 to Aug. 11, are scheduled to be held in the Seine.

Paris Mayor Anne Hidalgo finally swam in the Seine last week, fulfilling a promise to try and convince doubters that its waters will be clean enough to hold Olympic swimming events.

Decisions on whether to run Olympic events will be taken the night before, and early that same morning, with a technical committee including athletes, international federations, regional authorities and Meteo France making the call.

If the river is not deemed to be suitable, organisers have contingency plans: the marathon swimming event will take place at Vaires-sur-Marne, where the rowing and canoeing events are held, and the triathlon will be turned into a duathlon.