Geology
The Site
Lake Paladru is of glacial origin. It was carved out, probably in two stages, at times when the Alpine glaciers reached as far as Lyon.
The setting is typical of the Alpine foothills: wooded hills – old moraines – surround the lake and rise to about 800 metres. Fields and pastures alternate with forests dominated by chestnut, oak and beech. Small valleys, or “combes”, run down from the ridges to the lake, carrying the water of the catchment area. In the background, they open up views of the Mont du Chat in Savoie, the Chartreuse and Vercors peaks of the Dauphiné, the Belledonne range and, on clear days, Mont Blanc.
Key facts
Lake Paladru lies at an altitude of 492.40 m (NGF). It extends over the municipalities of Paladru, Montferrat, Bilieu, Charavines and Le Pin.
It is 5,300 m long, about 800 m wide on average (1 km at its widest), with an average depth of 25 m and a maximum depth of 36 m. Its surface area of 392 hectares makes it the fifth-largest natural lake in France, after Lake Geneva, Lac du Bourget, Lake Annecy and Lac d'Aiguebelette.
It is fed mainly by precipitation (rain and snow).
Its outlet at Charavines is the Fure river, which flows into the Isère.
A system of sluice gates regulates the outflow from the lake according to the needs of the mills along the Fure. In the second half of the 19th century, the river powered paper mills, steelworks, edge-tool works, weaving mills and more.
The lake holds 97 million m³ of water in total. A complete renewal of the water is estimated to take 3.6 years.
The lake level varies, by up to 2.50 m, which has consequences for the plants, wildlife and lakeside facilities.
Towards Charavines:
- Trou du Commissaire: a sheer drop close to the Bois d'Amour. A police superintendent from Voiron loved to fish here.
Towards Montferrat:
- La Véronnière: a favourite spot of the “véron”, the local name for the common roach.
- Île Loyasse: an island now under water
- Puits Jayet, between Paladru harbour and the Grands Roseaux
At the entrance to Paladru:
- Puits Lanfournet: setting of the legend of the White Lady
At Le Pin:
- The sunken town of Ars, near the beach