STORY: The race is on for Paris to clean up the River Seine in time for the Olympic Games this summer.
More than 100 years ago, athletes were able to swim in the river during the Paris Olympics in 1900.
It has become a lot dirtier since then.
Heavy rain causes the Parisian sewage system to overflow and be discharged directly into the river, polluting it with fecal bacteria.
As a result, bathing was banned in 1923.
But this summer, Olympic swimmers and triathletes are scheduled to compete in the Seine.
The city has been working hard to make that a reality.
But has Paris done enough to make the Seine safe?
The quality of the Seine's water has definitely improved.
The latest data shows it was suitable for swimming on six of the nine days between June 24-July 2.
To make that determination, testers measure the levels of two fecal bacteria - E. coli and Enterococcus faecalis.
The readings depend on rainfall and water temperature among other factors.
Paris built a massive underground storage basin designed to hold waste water and reduce the risks of pollution.
But whether that's enough to keep the bacterial concentrations below legal thresholds remains to be seen.
So what if the water is not suitable for swimming on event days?
Organizers can choose to postpone both events by several days.
After that, if the competitions still cannot take place, the marathon swimming event will move to the reserve site of Vaires-sur-Marne, and the triathlon will be turned into a duathlon -- just running and cycling--without the swimming.
