Lac des Rousses

The Lac des Rousses, formerly known as Lac and Lac Quinsonnet Quintenois, is a lake in the French Jura, in the Jura, around 20 km north- west of Nyon in the Franche -Comté. It is located in 1,058 m above sea level. M. on the communal land of Les Rousses just beyond the Swiss border.


The Lac des Rousses occupies an area of 97 hectares, is approximately 2 km long and up to 500 m wide. Its greatest depth is 19 m. The lake is located northeast of the village of Les Rousses, in the Jura high. It is located in a broad mountain valley, which forms the southwestern continuation of the Swiss Vallée de Joux. On its north-west side of Lac des Rousses and the valley is flanked by the wooded height of the Forêt du Risoux; in the southeast rises the ridge of Mont Noir. While the north-western shore rises relatively rapidly, especially on the southern shore of broad larger marshes.


In structural terms, the geologic Orbetal forms with the Lac des Rousses a syncline the Jura folds. The surface of the valley floor consists of calcareous and marly layers that were deposited during the Cretaceous period in a tropical shallow sea. They were taken much later in the Miocene and the Pliocene during the folding of the Jura Mountains, in their present situation. During high stages of the various ice ages the area was glaciated. Jura glacier rock material transported from the surrounding ridge in the valley, and it formed a quaternary sediment layer. Thus, the pool was lined with marl and clay layers, so that despite the porous calcareous subsoil bogs and a lake was formed.


The catchment area of ​​the Lac des Rousses amounts to around 13 km ². The most important tributary is the Bief Noir, which rises west of the Mont Noir, flows through a marsh area and flows from the south into the lake. Other short streams reach the lake from the surrounding slopes. Outflow is through the Orbe to the Northeast to the Lac de Joux. Thus, the Lac des Rousses in the extreme southwest of the watershed of the Rhine. The lake has a water content of about 10 million m³. The average residence time of water in the Lac des Rousses is estimated to be about a year.


The Lac des Rousses is located in a touristy both in winter and in summer busy region. Due to its altitude and position in a closed basin (formation of a cold air lake ) Lac des Rousses freezes completely in most winters. With snow covering the frozen surface is used for cross-country skiing. In summer, the Lac des Rousses is a popular destination for bathing or used for any purpose other water sports. In addition, the seawater used for treatment of drinking water for the surrounding communities is used.

The landscape around the Lac des Rousses is a nature reserve. She also belongs to the Parc Naturel Régional du Haut- Jura.