Artificial basin set in the Campania Apennines at 460 m above sea level. It receives its water from the Osento stream that originates in the Lacedonia area and has a fair flow of water, especially in winter.
In the sixties, the Capitanata di Foggia decided to build this reservoir to allow the collection of the torrent waters, and then put them in the riverbed during drought periods, to be used for irrigation purposes in the lands of the nearby Puglia. The artificial reservoir has a maximum full capacity of 17,100,000 cubic meters and is delimited by the municipal boundaries of Monteverde, Aquilonia and Lacedonia, all common members of the Alta Irpinia Mountain Community. Lake San Pietro or Aquilaverde (i.e. Aquilonia - Monteverde) today is a place of peace and rare beauty due to the very green crown of the surrounding pine forests and is a wetland affected by the passage of migratory fauna. Only the large dam makes us remember that we are on the banks of an artificial basin. In the part closest to the access road, the bank is low and slopes gently into the water; the other bank is characterized by large rocky walls, dominated by abundant vegetation. A large picnic area develops along the north-east side of the lake