PARIS — Mayor Anne Hidalgo on Wednesday assured Olympians that the River Seine will be safe for swimming and promised to take a dip into the waters before athletes dive in.

Open water swimming events are set to be held in the Seine in the upcoming Summer Games, but river pollution levels have sparked health and safety concerns.

The mayor had been set to take a dip on Sunday, but canceled. She told NBC News on Wednesday that the change of plans was due to weather and demands of the campaign…