Lush, murky and green pool…those are not the words that one would expect to be using while describing a pool used for the Rio Olympics 2016. However, that has exactly been the case, as not just one but two pools have turned a rich emerald shade.

The water polo pool has joined its neighbor in going green. CNN reports that on Wednesday, the water polo pool also mysteriously changed colors overnight. From a beautiful clear blue, the water suddenly turned a murky shade of swamp green. This happened a day after its neighbor, the diving pool, hit headlines all over the world by suddenly changing color. Both pools are located in the Maria Lenk Aquatics Centre in Rio de Janeiro. The pools are part of the extensive number of facilities that are currently hosting the Rio Olympics 2016.

After the first pool turned green on Tuesday, The Independent shared that Olympics officials were unable to provide a clear explanation to the phenomenon. However, they assured that the green pool water does not pose a health threat to the athletes. They also promised that the pool will be “fixed” for the next day’s events.

Contrary to what was promised, instead of one green pool, the water polo pool also turned green on Wednesday. CNN offered some explanations, which include the popular theory of an algae bloom. Lack of wind and the heat in the venue are seen as possible factors that support this theory.

A change in the pool’s alkaline levels is also a possible answer. All theories aside, the green pools may very well be an effect of poor maintenance work. Pools are treated with chemicals like chlorine, which inhibit growth of algae, among other things. The same is true even for home pools. A simple case of failed maintenance procedures is becoming a popular theory.

Regardless of the real cause, the organizing committee is adamant that the pools are safe to compete in. Unfortunately, the issue has thrown a shadow over the games and has drawn more attention than the actual competition.