In 1924, Bayernwerk AG put the Lake Walchen Power Plant into operation on the south shore of Kochelsee. Six pipes carry water from Walchensee 200 m down the mountain to the hydroelectric plant. In order to increase the amount of water available for the plant, a 7-km long tunnel was driven in the Karwendel to tap the Rißbach and Isar rivers, feeding Walchensee. Overall, Walchensee has an average volume of 1.3 billion cubic meters. Two smaller hydroelectric plants were built directly on Walchensee: one at the mouth of the Niedernach in the southeast and one on the Obernach in the southwest.