This reservoir is located northeast of Mérida at the beginning of the hydraulic system Aqua Augusta, which provided water for the whole southern area of the city.

Between two hills, it collects the water coming from channels and dams built in the Sierra Bermeja, as well as water coming from existing wells in the basin of the reservoir. Then, along a stretch of about 15 kilometres, channels are added to the main system bringing water from different springs like the one of Borbollón for example.

The primitive construction from the Augustean age was made up of a collection tower covered with dressed ashlars which was united to the reservoir wall through a parapet walk over a big semicircular arch. It seems that the original reservoir was constituted of a core of concrete cells filled with compacted earth, covered with a sloping wall of ashlars. Today this is all masked by a construction built in the first quarter of the 20th century.

Downstream, the wall rests on a colossal shoulder of land.

The part of the reservoir that is preserved is 200 metres long and 18 metres high. Our visit to the marsh must end with a walk through the oak groves and pastures of the Natural Reserve as well as a visit to the country house of Campomanes, a gift of the people of Mérida to who used to be Minister of Treasury under Charles 3rd.