While there was understandable concern about the water surrounding Rio de Janeiro leading up to the Olympics, now it seems the indoor pools are causing consternation. The water of the diving pool turned a lurid green overnight.
The Rio 2016 Local Organizing Committee has blamed the green hue of the water on a proliferation of algae they said was caused by heat and lack of wind in the venue. The diving pool is kept at a higher temperature than pools used for other events. The aquatic centre is different from usual as well because it's an outdoor arena. Experts say that ultraviolet rays from the sun can break down some disinfectants, causing them to evaporate. Algae can then bloom, leading to a rise in pH.
The committee insisted that the water had been tested and there was no health risk posed to athletes. Organizers hope to have the pool returned to clear blue immediately. That may be difficult, however, because harsh chlorination of the water is often required to fix this issue, and those high levels of chlorine aren't good for people to use for swimming or diving.