Lac d'Emosson is a reservoir in the canton of Valais, Switzerland. It is located in the municipalities of Salvan and Finhaut. The closest major city in Switzerland is Martigny. The lake has a surface area of 3.27 km² and an elevation of 1,930 m. The maximum depth is 161 m. The purpose of the dam is hydroelectric power generation. Water from the reservoir first powers the 189 MW Vallorcine Power Station downstream and just over the border in Châtelard, France. Water is then sent through a headrace tunnel to the 162 MW La Bâtiaz Power Station, 12 km (7 mi) to the east in Martigny, Switzerland.