An individual reported that water was shooting vertically out of an underground penstock (diameter: 600 mm) located along a path used to access a hamlet. Freezing temperatures had caused ice to form on the surface of the penstock. On 10 December, the power station was shut down and the penstock was excavated. A small hole was found and repaired. The power station resumed operation on 13 December. The leak was adjacent to an old high-voltage line that had been abandoned after a ski lift had been torn down. Leakage currents flowing into the ground may have created a catalytic phenomenon that weakened the penstock. The same incident had already occurred in April and June 2009.