A reservoir (etymology: from Frenchréservoir a "storehouse" ) is a natural or artificial lake, storage pond or impoundment from a dam which is used to store water. Reservoirs may be created in river valleys by the construction of a dam or may be built by excavation in the ground or by conventional construction techniques such as brickwork or cast concrete.
The term reservoir may also be used to describe naturally occurring underground reservoirs such as those beneath an oil or water well.
Lac de Monteynard-Avignonet is an artificial water reservoir for the Électricité de France power station on the Drac River. It belongs to the department of Isère. It is bounded by the canyons of the Drac and Ebron.
The lake was created in 1961, when the 145-metre-high dam was built. The lake is 10 kilometres long, and in some places up to 300 metres wide.
This lake is often windy and wavy. It is considered to be one of the best places for windsurfing and kitesurfing in Europe. It is also an important site for fishing, as it has a great variety of fish species. Swimming in the lake is permitted.
The lake is bordered by the following municipalities: Avignonet, Cognet, Marcieu, Mayres-Savel, Monteynard, La Motte-Saint-Martin, Roissard, Saint-Arey, Sinard, Treffort.
In 2007 two simple suspension bridges were built across the Drac and Ebron. The bridges are 220 and 180 metres long, respectively, and used 1200 metres of cable. Depending on the level of the water in the lake, the Drac bridge is 45—85 metres high above the lake. Construction of the bridges was achieved with the help of helicopters.