Hydroelectric dam reservoir. Ice floating in the reservoir of a dam in the Swiss Alps in late June. Electricity pylons are seen in the background, running past two sections of dam (upper centre and upper right). This is Totensee, the highest of five dam lakes in Grimsel Pass, which is at an elevation of 2165 metres. The dams are operated by KWO Grimsel Power, and mainly provide power during the winter months. The Totensee dam is 20 metres tall, and was built in 1950. It dams the Totensee river, forming a lake that can hold 2.6 million cubic metres of water.