Chañaral Bay copper tailings

Bahía de Chañaral

From 1938 to 1990 about 400 million tonnes of tailings from the Potrerillos and El Salvador copper mines were dumped, by way of the Salado river, on the coast of the Atacama Desert. At Chañaral the sea now lies a kilometre away behind a beach made of mine waste, from which wind carries dust with arsenic and copper into the town.

Status

Not addressed

Dumping at sea stopped in 1990 when an inland sedimentation dam was built. The tailings stayed on the coast: the artificial beaches are eroding, and the Salado river floods of 2015 and 2017 reshaped them (Lazo et al. 2025; Arróspide et al. 2026). The sources consulted describe no remediation work.

Story

The Potrerillos mine, at 2,850 m, began producing in 1926; from 1959 extraction moved to the El Salvador mine, still working today. Tailings from the concentration plants were poured untreated into the Salado river, a usually dry channel that carried them to the sea.

From 1938 to 1975 the discharge ended in Chañaral Bay: about 204 million tonnes in 37 years. In February 1975 the dumping point was moved 12 km north to Agua Hedionda Bay, which received roughly another 195 million tonnes in fifteen years. In 1990 a sedimentation dam was built inland; clarified water kept reaching Agua Hedionda until 1994 (Lazo et al. 2025).

The rocky coast responded with rapid advance of the shoreline. Once the supply ended, the artificial beaches entered a phase of strong erosion. The town of Chañaral lives beside the deposit: street dust averaged 24 mg/kg of arsenic and 607 mg/kg of copper, and arsenic falls with distance from the tailings, a sign that wind spreads it from there towards the houses (Moya et al. 2019).

Timeline

1926The Potrerillos mine starts producing.

1938Tailings begin to reach Chañaral Bay down the Salado river.

1959Extraction moves to the El Salvador mine.

1975February: dumping is moved 12 km north to Agua Hedionda Bay.

1990An inland sedimentation dam is built: tailings dumping at sea ends.

2015A Salado river flood erodes and reshapes the tailings beach; another follows in 2017.

Health

Despite the concentrations in dust, urinary metal levels measured in Chañaral were low: 90% of people had inorganic arsenic and metabolites below 33.2 µg/L, and copper was detectable in fewer than 6% of samples (Moya et al. 2019). In the town's schools, trace elements in PM2.5 were higher inside classrooms than outdoors (Mesías Monsalve et al. 2018).

From the literature

Species that acted on one of this site's contaminants in at least one study. The list is automatic and takes no account of this site's soil, concentrations or climate.

Plants

Pteris vittataChinese brake fernArsenicEvidence: field
Populus albaWhite poplarCopperEvidence: field
Arundo donaxGiant reedArsenicEvidence: greenhouse
Lemna minorCommon duckweedArsenicCopperEvidence: laboratory
Azolla carolinianaCarolina mosquito fernArsenicEvidence: laboratory

Fungi

Funneliformis mosseaeArsenicCopperEvidence: greenhouse
Rhizophagus irregularisCopperEvidence: greenhouse
Aspergillus nigerBlack mouldCopperArsenicEvidence: laboratory
Fomitopsis pinicolaRed-belted conkArsenicCopperEvidence: laboratory
Mucor circinelloidesArsenicEvidence: laboratory
Suillus luteusSlippery jackCopperEvidence: laboratory