The company Colbún (in partnership with ENEL/Endesa) promoted the construction of the Angostura dam in the late '90s in an atmosphere of transversal dissatisfaction among Mapuche Pehuenche communities in the Biobío region. Productive potential, tourism, and environment protection conciliated through collaboration with affected communities lying at the premises in the argumentation by the project promoters. Something that seems not to be translated into reality nowadays. The local Mapuche Pehuenche and neighbouring communities complained [1] [2] [5] that the dam (with an installed potential of 316MW) would inundate a sacred land of high ecological value and asked for its inclusion in the list of World Human Heritage. The Biobio region has long suffered destructive interventions, that include the other three hydroelectric projects Palmucho (32 MW), Ralco (690 MW), Pangue (467 MW).  The social movements that at once organized in objection to the reservoir ended up being criminalized, delegitimize, and annihilated through police intervention, while communities were been resettled without proper consultation [1]. 

In 2014 the plant was inaugurated. By that time, the local population was paying the higher cost of electricity in the entire country, despite living next to the hydroelectric plant [3]. Most people adapted to living without electricity due to the impossibility to pay the costs. Just two years later the Chilean government approved a law with the aim of equalising the prices between major and minor urban centres [4]. Today, the entire area around the dam reservoir is promoted as a tourism attractor [6].

"The project is situated approximately 600 km south of Santiago, in the municipality of Santa Barbara y Quilaco in the region of the Bío-Bío River 63 km south-east of the city of Los Angeles; downstream of the confluence of the Bío-Bío River with the Huequecura River, in the gully known as Angoustura del Piulo where the main intake starts.

The main civil works include the construction of an earth dam approximately 1.6 km long and 25 metres high on the left bank of the river and the construction of a Rollcrete dam 125 m long and 63 m high with a spillway incorporated along the Bío-Bío River.

The purpose of the project is the generation of electricity through a plant with an installed capacity of 316 MW, supplied by the reservoir of water formed by the two rivers; 1,542 Gwh of energy will be produced annually." [7]