@Jxckson
On the right of the picture, slightly below the gates, you can see two square concrete structures. They are two pools (not huge, but both fit more than two hippos comfortably). The fenced structure in the midle, where the apparent cascade used to let it's water fall, was probably another pool.
Mery, the last elephant in Parque de Las Leyendas and in the entire country of Peru died in 1987.
@Jxckson
Yes, it's not the most suitable exhibit for a hippo indeed, but also, it's not the worst. The zoo has another hippo exhibit, which is the main one, that has a similar sized water area.