The lake is supplied entirely from the aquifer, rainfall and runoff, with one outlet at the southern end. A sewage treatment plant filters most of the raw sewage from the surrounding communities. Constructed in 1996, it features pipelines transporting the sewage from every major community around the lake to the treatment plant on the
Lying within the northern part of the
One third of the lake was donated to the Church by the noble family Alberici of Orvieto. In recognition of the donation the Alberici family was honored with a ceremony three times a year performed by the Bishop of Orvieto.