Water mainly came via the Avens river Nar from lacus velinus near Reate. Its water came from mountains. Marius Curius Dentatus has drained the waters of the lake into the river Nar. In doing so, he created the marmore waterfalls:

The Marmore Falls, extolled during the centuries for its beauty, appears like a roaming water column distributed on three drops. Wrapping the flora in a cloud of white foam , cover a different in high of 165 metres. The scenery disclosed to the visitors eyes is the work of men made since centuries, from the Roman period, tried to canalize the waters of the Velino river to fall the into the Nera river.

Its history began in 271BC when the Roman consul Curio Dentato made a reclaimed work in the plain of Rieti realizing a canal of beyond two kilometers up the cliff of Marmore.

The lake is now known as Lago Piè di luco

References:

"Rivers and the Power of Ancient Rome" By J. B. Campbell

Dictionary of Greek and Roman Geography: Iabadius-Zymethus by Sir William Smith

Water mainly came via the Avens river Nar (that goes into Tiber) from lacus velinus near Reate. Its water came from mountains. Marius Curius Dentatus has drained the waters of the lake into the river Nar. In doing so, he created the marmore waterfalls:

The Marmore Falls, extolled during the centuries for its beauty, appears like a roaming water column distributed on three drops. Wrapping the flora in a cloud of white foam , cover a different in high of 165 metres. The scenery disclosed to the visitors eyes is the work of men made since centuries, from the Roman period, tried to canalize the waters of the Velino river to fall the into the Nera river.

Its history began in 271BC when the Roman consul Curio Dentato made a reclaimed work in the plain of Rieti realizing a canal of beyond two kilometers up the cliff of Marmore.

The lake is now known as Lago Piè di luco

References:

"Rivers and the Power of Ancient Rome" By J. B. Campbell

Dictionary of Greek and Roman Geography: Iabadius-Zymethus by Sir William Smith