Paris' River Seine is so polluted that Olympic athletes weren't allowed to swim in it

• The Olympic men's triathlon was rescheduled due to water pollution in the River Seine.
• World Triathlon said water tests did not meet its threshold for swimming.
• If the pollution doesn't subside, swimming might get dropped, leaving it as a duathlon.

Olympic triathletes might have to become duathletes because Paris' Seine River is too polluted for swimming.

World Triathlon, the international governing body for the Olympic and Paralympic sport of triathlon, said on Tuesday that the men's triathlon would be postponed due to poor water quality.

It made the announcement at 4 a.m. local time, five hours before the race was due to start.

It was being postponed until Wednesday at 10:45 a.m., officials said, in the hope that the water quality would improve.

The statement blamed "meteorological events beyond our control, such as the rain which fell over Paris on July 26 and 27," for the poor quality of the water in the historically polluted Seine.

Its rules set a maximum number of E. Coli or Enterococci colonies per 100 milliliters at 900, and a maximum number of Enterococci colonies at 330.

It didn't say what the readings were, only that they were too high in parts of the course.

The river's pollution levels have long been a topic of concern — swimming in the river was banned for 100 years before the Paris games.

Officials mounted a huge effort to clean up the river for the contest, with the Paris city government pegging the cost at $1.5 billion since 2015.

French officials, including Paris Mayor Anne Hidalgo and the French sports minister, swam in the river in recent weeks to prove it was sage.

President Emmanuel Macron said he would but did not end up making the attempt.

World Triathlon said it hoped the triathlons for men and women could take place on July 31.

It has a contingency date of August 2 if not. If the water was still too dirty then, the event could be cut to a duathlon, featuring just running and cycling.