Although glacial lake outburst floods (GLOFs) have occurred repeatedly in many places around the world, perhaps no country has as much experience with managing such lakes as Peru. This technical report is a distillation of the experiences and knowledge acquired during seven decades of active lake management. The goal is to provide lessons learned and case studies that may benefit the global community as each country addresses its own glacial lakes challenges. It stresses that local efforts must adapt to the unique context of each country, lake, and valley, and that each case requires action based on the best locally available knowledge and engineering. (Excerpt, modified).