When Olympic triathletes plunged into the Seine river close to the Alexandre III bridge in Paris on July 31, they were making history—and not just by going for gold.
The event, which also saw the competitors cycle and run along the Champs-Elysées and past the Grand Palais, was far more than an eye-catching sporting spectacle. It also marked a significant milestone in the ambitious €1.4 billion ($1.5 billion), multiyear plan led by Paris and the broader Île de France region to clean up the Seine.
There were real concerns that the triathletes might not make it into the river. After failed water-quality tests, the swimming leg of the triathlon seemed like