The lake system of Mantua including Vallazza represents a huge detention basin for the waters of river Mincio, when the river has to absorb the overflow of the floods of river Po. The large sedge formations and the riparian woodlands are temporarily submerged with water and are able to maintain, thanks to the periodicity of the floods, their aspect.
The big area of Vallazza is probably of very ancient origins. One of the human activities that has shaped the current aspect of the area was the excavation of clay: this activity has left in the river valley several isolated or grouped small lakes, often directly communicating with river Mincio. For these features, the quarries have achieved their own natural balance deserving safeguard.