The History of Guatapé Reservoir: How a Valley Became a Lake
How the Guatapé reservoir was created, the town that was flooded, and why El Peñol Rock became Colombia's most iconic landmark.
The turquoise water you see from the top of El Peñol Rock hasn't always been there. Beneath the surface lies the old town of El Peñol — flooded in the late 1970s to power Colombia's electricity grid.
Before the Dam
The valley was home to farmland, small villages, and the original town of El Peñol. The Nare River ran through it. Families had lived there for generations. El Peñol Rock — the massive granite monolith — stood alone in a green valley, not surrounded by water.
The Dam Project
In the 1970s, Colombia's state electricity company (EPM — Empresas Públicas de Medellín) built a hydroelectric dam on the Nare River. The project created Embalse Peñol-Guatapé, a massive reservoir covering over 1,886 hectares. The dam began generating power in 1978 and today supplies roughly 30% of Colombia's electricity.
The Flooding
The original town of El Peñol was gradually submerged as the reservoir filled. Residents were relocated to a new town built on higher ground — the "New Peñol" that exists today. The process was traumatic for many families who lost ancestral homes and farmland. A cross and part of the old church remain visible above the water line as a memorial.
The Name Dispute
Guatapé and El Peñol have been fighting over the rock for decades. You can see a giant painted "G" on the rock face where Guatapeños started writing their town's name — El Peñol residents stopped them before they could finish. Only the "G" and part of the "U" were completed. The dispute is ongoing and only half-joking.
Guatapé's Reinvention
What could have been an economic disaster became a tourist goldmine. The reservoir attracted visitors, the zócalo tradition made the town photogenic, and El Peñol Rock became an iconic landmark. Today, tourism is Guatapé's primary industry — a remarkable transformation from the farming community that nearly lost everything to the dam.
Seeing the History
On boat tours, guides sometimes point out where the old town lies beneath the water. The Museo Histórico in Guatapé has photos and artifacts from the original El Peñol. And the painted "GU" on the rock face tells the whole story of two towns fighting over a stone.