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The reserve Lake Canterno includes one of the most extensive karst basins in Lazio: it is in an area surrounded by the territories of Ferentino, Fiuggi, Fumone and Trivigliano.

The lake has a perimeter of 5 km and a depth varying between 15 and 25 meters and lies in a karst depression on a plateau framed by the Ernici Mountains, and is surrounded by an almost ‘lunascape’ environment with shores having no tall trees.

What we see today is the result of a geomorphological process of transformation that did not happen long ago, so that Lake Canterno can be considered one of the youngest lakes in Lazio.

The area occupied by the lake today was entirely cultivated until 1816, with the exception of the deepest area of Sgolfo around a whirlpool called the Pertuso – the hole (which has a shape similar to a 2.50 m high door of 1,50 m width) which drained the waters of the northern slope of Mount Maino.

This configuration was maintained until 1816, the year when the first ‘appearance’ of Lake Canterno occurred. In that circumstance, the rainwater hole originated in a small lake in the Sgolfo depression for a short time.

The small lake was formed for a second time in 1821 when the waters reached the Pertuso: the progressive closure of the latter, thanks also to the efforts of man, quickly led to the formation of the lake.

From that moment on, the breaking up of the ‘diaphragm’, the emptying of the basin and the subsequent transport of detritic materials gave birth to an “intermittent” lake, at reasonably regular intervals.

The number of so-called “disappearances” of the lake, lasting a few days or several months (the sources are discordant in this regard), would have been twelve, of which the last in 1925.

In 1942, the Società Elettrica Romana drained the lake to create an artificial tunnel of about 2 km long and started to use the lakeside water for hydroelectric purposes, exploiting a drop of about 300 m.

In order for the whirlpool of Pertuso to continue its regulating function of the water outflow, a gully tower was built, creating a kind of dam in the middle of the lake. In addition to a larger water supply, a free-flowing 6800-m long floating channel was also created, bringing water directly from Guarcino.

The channel travelling to the lake was part of the waters of the river Cosa. In certain times of the year, or as a result of a pumping system, the rainwater accumulated in a depression adjacent to Canterno called “Lattanzi” Lakes (from the surname of the family owner of the area in the territory of Trivigliano).

Lake Canterno, while remaining a “transformed” basin for hydroelectric purposes, has become an integral part of the Regional Nature Reserve managed by the Regional Park Authority Monti Ausoni and Fondi Lake and set up to preserve a landscaped area rich in flora and fauna fauna. The arrival of traditional birds of the wetlands such as the horned heron, the chamois, the red heron has been recorded.

The park is now enjoyable thanks to equipped paths and a facility with an adjoining picnic area along the eastern shore.