After a storm, the men’s individual triathlon race at the Paris 2024 Olympics has been postponed due to poor water quality levels in the River Seine.

“Despite the improvement on the water quality levels in the last hours, the readings at some points of the swim course are still above the acceptable limits,” announced the the sport’s governing body, World Triathlon.

Famously, Paris spent about $1.5 billion trying to clean up the famous river before the Games, but any time there’s a storm the pollution waves right into the Seine.

While the specially created new rainwater storage basin – called the Austerlitz basin – can hold 20 Olympic swimming pools worth of water, it’s still not able to contain all the rain runoff.