Carén Reservoir, reservoir in Chile

The Carén Reservoir is a water storage facility in the Santiago Metropolitan Region of Chile, set among dry hills south of the capital. A dam wall holds back the water, and the surrounding land is largely open with few structures in sight.

Since 1987 a wall has contained tailings from the El Teniente mine, brought 87 km from the Colón concentrator plant through the 10 km Carén tunnel and a siphon over the Cachapoal River to the Carén stream. The transport route partly reused the Rancagua-Doñihue branch line, abandoned since 1974. By 2013 the wall held 2 million cubic metres of material enclosing 176 million cubic metres of tailings. On 16 April 2006 a failure released toxic material along 17 km of the stream.

The reservoir lies inside the Roblería del Cobre de Loncha National Reserve, in Alhué commune, Melipilla Province. Its name comes from the Carén stream, whose clear waters leave the reservoir and flow on to the Alhué stream. Tailings arrive from the Colón concentrator plant 87 km away, carried through the 10 km Carén tunnel and a siphon that crosses the Cachapoal River.

The reservoir is reached by road from Santiago, and the surrounding area has little infrastructure, so it is worth coming prepared with water and supplies. The open terrain makes walking around easy, but there is limited shade, which matters on sunny days.

Carén is a tailings reservoir, not a water supply: since 1987 a wall has held tailings from El Teniente, brought 87 km from the Colón concentrator plant through the 10 km Carén tunnel and a siphon over the Cachapoal River. By 2013 the wall held 2 million m³ of material containing 176 million m³ of tailings.