Monturaqui-Negrillar-Tilopozo Aquifer

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The Monturaqui-Negrillar-Tilopozo Aquifer is an aquifer in the commune of San Pedro de Atacama in inland Antofagasta Region, Chile. [1] The aquifer lies in the Atacama Desert straddling Puna de Atacama plateau on the western side side of the Andes. The aquifer discharges naturally in Salar de Atacama allowing for the meadows of Tilopozo (Spanish: Vegas de Tilopozo) to exist at the southern fringes of the salt flat. [2] [3]

Contents

The aquifer lies in a 60 km long north-south trending depression runs south from Salar de Atacama filled with permeable volcanic rocks [4] of the Salin Formation. [5] The flow [6] and composition of its waters are influenced by the El Negrillar volcanic field, [7] which lies in the middle of the groundwater body and separates it into two halves. [8]

The aquifer has for decades been tapped for water by mining companies. The copper mine of Escondida supplied itself with freshwater from 1998 to 2019 from a well field in the aquifer located 78 km east of the mine. [2] This well field had an installed capacity to extract 1400 liters per second. [2] [A]

Illegal water extraction lawsuit

In 2022 the mining industry's use of the aquifer's water was legally challenged by indigenous Atacameño communities [B] due to purpoted environmental harm. [9] The legal case was joined by a lawsuit by Consejo de Defensa del Estado (CDE) against Minera Escondida, Minera Zaldívar SpA and Albemarle Limitada. [3] [C] These companies were charged with illegal extraction of water, [3] leading among other things to groundwater level to drop in the Tilopozo area more the 25 cm allowed by previous extraction permits. [2]

In its defense Albemarle Limitada have asserted that its extracts only surface water from a spring and that its use is minimal (0.5% of the histoirc water uptake) compared to the other companies. [10] [11] Minera Escondida for its part argued that any effects of its water extraction have not had time to manifest at the meadows of Tilopozo, due to the slow movement of groundwater, and hence that it was the extraction of the other two companies that had impacted it. [10]

A series of settlements and compensatory measure at the First Environmental Court of Antofagasta ended the case in late 2024. [9] [11] In a December 2024 conciliation agreement the three companies were to compensate economically, socially and environmentally the indigenous Comunidad de Peine as well as paying for damages to the meadows of Tilopozo and the lakes of La Punta and La Brava. [1]

Zaldívar avoided premature mine closure on May 2025 when Chile's Environmental Evaluation Service extended its continental water use rights until 2028. [9]

Environmental damages related to water extraction from the aquifer include the loss of recharge capacity and diminished biodiversity on surface. [3] Full natural regeneration from these damages is estimated to happen no earlier than year 2200. [3] The groundwater-dependent meadows of Tilopozo had consistently shrunk in area and vigour since 2007. [2] It has also been argued that groundwater extraction risked the extinction of the caracol de Tilopozo, an endemic snail species. [10]

Notes

  1. ↑ At present Escondida is supplied with water from a desalination plant near Caleta Coloso in the coast. [2]
  2. ↑ These were Comunidad Indígena Atacameña de Peine with the support of Consejo de Pueblos Atacameños. [3]
  3. ↑ Minera Escondida which operates Escondida, Chile's largest copper mine. Minera Zaldívar Spa which operates the copper mine of Zaldívar and Albemarle Limitada extracts lithium from Salar de Atacama. [9] Minera Escondida is majority owned by BHP and Minera Zaldívar Spa owned by Antofagasta Minerals and Barrick Mining.

References

  1. 1 2 Pardo, Jorge (2024-12-18). "Primer Tribunal Ambiental de Antofagasta aprueba conciliación en la demanda por daño ambiental en contra de 3 mineras por el acuífero de Monturaqui – Negrillar y Tilopozo". Profesionales del Cobre (in Spanish). Retrieved 2025-07-21.
  2. 1 2 3 4 5 6 "Primer Tribunal Ambiental multa con más de US$8 millones a Minera Escondida por daño ambiental". Electrominería (in Spanish). 2024-12-17. Retrieved 2025-07-21.
  3. 1 2 3 4 5 6 "CDE demandó a mineras Escondida, Zaldívar y Albemarle por dañar Salar de Atacama". Diario UChile (in Spanish). University of Chile. 2023-07-21. Retrieved 2025-07-20.
  4. ↑ Rissmann et al. 2015, p. 165.
  5. ↑ Anderson, Low & Foot 2002, p. 135.
  6. ↑ Rissmann et al. 2015, p. 167.
  7. ↑ Rissmann et al. 2015, p. 170.
  8. ↑ Anderson, Low & Foot 2002, p. 139.
  9. 1 2 3 4 "Antofagasta Minerals avoids closure of Chile's Zaldívar copper mine with key water approval". BNamericas . 2025-05-16. Retrieved 2025-07-19.
  10. 1 2 3 "CDE, comunidades y empresas mineras concluyen argumentos en demanda por daño ambiental de acuífero en el Salar de Atacama". Revista Nueva Minería y Energía (in Spanish). 2024-01-20. Retrieved 2025-07-20.
  11. 1 2 Guillou, Víctor (2024-12-17). "Aprueban conciliación entre el CDE, comunidades indígenas y empresas minerasen causa por daño ambiental en el salar de Atacama". La Tercera (in Spanish). Retrieved 2025-09-01.
Bibliography

24°27′41.99″S68°52′9.71″W / 24.4616639°S 68.8693639°W / -24.4616639; -68.8693639

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