A Second Olympic Pool Turns Green, Officials Say Algae Not The Culprit

Olympic athletes and fans were in for a surprise on Tuesday when the Olympic diving pool in Rio turned a very prominent shade of green.

The neighboring pool, used for water polo and synchronized swimming, remained mysteriously untouched at first:

But then that pool, too, appeared to be changing colors as of late Wednesday afternoon:

Olympic officials initially said the cause was a “proliferation of algae” due to “heat and a lack of wind,” however FINA, the international governing body of aquatics, released a statement Wednesday afternoon that blamed the pH level of the water for the discoloration. Via the Los Angeles Times:

FINA can confirm that the reason for the unusual water color observed during the Rio diving competitions is that the water tanks ran out of some of the chemicals used in the water treatment process.

As a result, the pH level of the water was outside the usual range, causing the discoloration. The FINA Sport Medicine Committee conducted tests on the water quality and concluded that there was no risk to the health and safety of the athletes, and no reason for the competition to be affected.

Olympics spokesperson Mario Andrada told reporters that the team in Rio was in the process of balancing the pH. Andrada blamed a lack of testing and preparedness for the number of athletes who’d be using the pool:

“We probably failed to note that with more athletes, the water could be affected,” Andrada told The New York Times. “The people in charge of the pool should have done more intensive tests.”

So is the pool really safe for swimming, as officials assert? Vox spoke to Nate Hernandez, a director of aquatics at a company that maintains pools at resorts and public facilities. He didn’t caution that the pools may be unfit for use, but he did say that “multiple things would have to break down” for such a result to happen. Hernandez confirmed that algae was likely not the cause given that it likely wouldn’t bloom that fast in such a large pool.

The Vox reporter asked if Hernandez if he’d be embarrassed if this happened at one of his pools. His reply? “I’d be fired.”