The history of this infrastructure dates back to the early 20th century, when the Eastern Pyrenees Hydrographic Confederation began studies on the Llobregat river. Although the idea was old, the Spanish Civil War and railway protection delayed the project until the 1950s.

The final civil works were carried out between 1970 and 1976. The official inauguration was led by the then King Juan Carlos I and Queen Sofia, featuring an exceptional performance of la Patum in Berga and a visit to the new town of Sant Jordi.

By 1978, the reservoir reached its maximum level, permanently covering buildings, bridges, and the old railway line. This process meant the disappearance under water of settlements that had once housed over a thousand inhabitants, mostly linked to the mining industry in Cercs.