Lake Arvo, Artificial reservoir in Province of Cosenza, Italy.

Lake Arvo is an artificial reservoir located in the Sila mountains within Cosenza Province. The water body is held back by a dam constructed from compacted earth that blocks the Arvo, Bufalo, and Fiego rivers.

The reservoir was created between 1927 and 1931 by damming the Arvo river and the Bufalo and Fiego streams for hydroelectric power. The earth-fill dam, 280 m long and 22 m high, was the longest of its kind in Italy at the time; work ended in 1932, when Prince Umberto of Savoy and Maria José inaugurated the complex. Archaeologist Italo Biddittu found traces of Homo erectus on the lake shores.

The lake's name comes from the Arvo river, which was dammed together with the Bufalo and Fiego streams. On an islet in the Aprigliano stretch, yellow-legged gulls nest in several dozen pairs, among the highest breeding sites in Italy. The reservoir also hosts rowing competitions, and an Olympic rowing centre is planned.

The lake is flanked by the SS 108bis road, which runs along its shore and gives direct access to the banks. The northern shore is jagged and the southern one straighter, so orientation along the water differs from one side to the other. The bottom is mainly sand and pebbles.

The dam holding back the water uses clay and compacted earth rather than concrete, which is unusual for a reservoir of this size. This simple construction method from the 1920s has proven durable over the decades.