In the early years of the twentieth century, it became clear that power supply expansion would be essential in order to meet future demand in the country. Therefore, in 1922, Empresas Eléctricas Asociadas, under the guidance of engineer Juan Carosio, joined the project of engineer Pablo Boner: the staggered exploitation of water resources of the Rímac and Santa Eulalia Rivers.
To implement the project, the physical environment had to be modified. First, the watercourse of the Santa Eulalia River had to be dammed, the waters of the Rímac River diverted to the Santa Eulalia River, and the Callahuanca, Moyopampa and Huampaní power plants built.
A trans-Andean tunnel was also built to convey water from Marcapomacocha Lake (Junín) to the Pacific watershed. The tunnel —a true engineering feat— was completed in 1962: it is 10 km long and currently the highest in the world. The water running through the tunnel feeds Huinco Power Plant and others.
The power station is located in a semi-circular 108-metre cavern, measuring 31 meters across and 24 metres high. Because the Santa Eulalia River runs through a narrow gorge near Huinco, which prevented the construction of the plant or a switchyard, the station is reached through an 858-metre-long access gallery. However, the leaning gallery shortens the length of the penstock, which allows the rock to absorb 50% of water pressure, and thus reduce its operating costs by over 50%.