Today intimately linked to the landscape, Lac de Saint-Agnan has only existed since 1969, when the dam to which it owes its origin was inaugurated. This water reservoir, with a volume of 4,700 thousand m³ spread over 328 acres (133 ha) is fed by two main streams, the Cousin and the Trinquelin. Its 524 ft (160 m) long and 52 ft (16 m) high landscaped retaining dike was made of compacted granite rock. In addition to its tourist interest, this dam allows the supply of drinking water to around thirty villages and provides electricity.