Glacial lake at the base of Nevado Hualcán (6165 m, in the background). The level of this lake was lowered through a system of tunnels in order to reduce the outburst hazard. Nevertheless, in 2010 an ice avalanche led to an impact wave overtopping the bedrock dam and evolving to a debris flow and flood that caused some damage in the Quebrada Hualcán all the way down to the town of Carhuaz.