Guardialfiera Lake, also known as Lake Liscione, is an artificial lake formed in the 1960s and 1970s by raising a dam on the Biferno River in Molise to provide drinking water to surrounding villages for domestic, agricultural, and industrial use.
The dam is a gravity dam, consisting of an embankment waterproofed on the inside with a thick layer of concrete.
The lake has a maximum surface area of 7.45 km², and the underlying drainage basin covers 1,043 km². The lake's depth varies from 2 to 3 meters, with peaks of over 20 meters, and the lakebed is predominantly sandy and pebbly. The lake, elongated from southwest to northeast, is largely bordered by the Biferno Valley State Road 647, which overlooks much of it with a series of viaducts.
To create the lake and the dam, an ancient bridge, presumably Roman[1], was submerged by water: this is the Ponte di S. Antonio or Ponte di Annibale, visible during the dry summer periods in the vicinity of Monte Peloso. The bridge was visible again from 1 September 2017 until approximately 30 November 2017 and has been visible again since May 2021.