Photo : Antimuonium / Wikimedia Commons (CC BY-SA 4.0)
Le Lac vert (Passy)
Lac Vert is a small natural lake in the commune of Passy, in Haute-Savoie, at 1,266 metres' altitude. It measures about 140 metres long by 80 wide, with a maximum depth of 9.3 metres. It formed after the Dérochoir landslide of 1471, which blocked the Arve and dug depressions in the debris, filled with water over the centuries. With no natural tributary, it is fed by karst seepage.
Its very clear water takes on a characteristic green tint, due to the presence of cyanobacteria. Five rocks emerge from its surface. The site has been listed since 14 June 1909, and you can see rare dragonflies there, such as the arctic emerald, as well as, sometimes, golden eagles in the sky.
A path goes round the lake and lets you see it from different angles. The car park is also the starting point of several hikes that offer a higher view of the lake. Very popular, the site is served in summer by a shuttle from Plaine-Joux to limit crowds.
