Glencore-Antapaccay, Espinar: international expert confirms validity of OEFA’s findings about mining contamination

The studies produced by the Peruvian government agency for environmental evaluation and supervision, OEFA (Organismo de Evaluación y Fiscalización Ambiental) about the origin of the contamination of water, soil, air, flora and fauna in the province of Espinar, Cusco, have proven that it stems from the operations and tailings deposits of the Antapaccay mine, owned by Glencore (Switzerland-UK). 

This evidence is key to the constitutional protection action (“demanda de amparo”) presented by the Platform of persons affected by toxic metals of Espinar (Plataforma de afectados por metales tóxicos – Espinar, PAMETEC), together with the community of Huisa and a group of citizens. They are currently waiting for a new date for the court hearing, which was programmed and postponed already three times since May.

Despite evidence from more than 1,500 pages of scientific reports, Glencore continues to deny OEFA’s disturbing findings. In May, Glencore’s chairman, Kalidas Madhavpeddi, once again repeated the claim that the contamination was ‘caused by natural mineralisation’, citing other studies commissioned and paid for by the company itself. In response to a new report by FairFinance, Glencore recently published explanations on its website questioning the quality of OEFA’s studies.

To the contrary of these statements, an independent review of the OEFA studies on the causes of surface and groundwater contamination in the vicinity of the Glencore-Antapaccay mine in Espinar, conducted by a scientist from the renowned ETH University in Switzerland, has confirmed the validity of the findings of these studies.

The expert is Bernhard Wehrli, professor emeritus of aquatic chemistry at the Institute of Biogeochemistry and Pollution Dynamics at the Swiss Federal Institute of Technology in Zurich, Switzerland. Known by its German acronym ETH (Eidgenössische Technische Hochschule), this university ranks among the top 10 in the world. Professor Wehrli has more than 40 years of experience studying water quality on four continents, including in mining contexts. In the document, Wehrli states that he has no conflict of interest in this case and that the review was conducted scientifically and without remuneration.

According to Prof. Wehrli, “the OEFA study started with a clear environmental model and was based on an extensive set of sampling and analysis stations […]. Documentation of the study sites, sampling procedures, analytical methods and data analysis shows high professional and scientific standards […]. The evaluation and interpretation of data in terms of water quality assessment was based on accepted national and international standards […]. Together with the monitoring of ground-water wells and hydrological information on flow paths of surface- and groundwater, the data allow drawing cause-effect relations between mining activities in the area and mining-related water pollution.”

To answer the key question in OEFA’s analysis, namely whether there is a causal relationship between mining activities and water pollution, the expert states that: “The detailed information available in Informe 00095 and 00144 forces this review to answer with a clear yes.”

Wehrli concludes by stating that “the Oefa authority is commended for one of the most comprehensive and thorough environmental assessments this reviewer has encountered.”

As next step, the expert advises to urgently carry out a state-of-the art health impact assessment. Also, in order to bring the mining operation to the level of international standards, he recommends that “best practices for tailings management, confinement and environmental restoration of the dump sites, improved mine-water treatment and recycling need to be implemented by the operators and critically monitored by public authorities.”

Read the review of the Environmental Causality Assessment regarding surface water, sediments, hydrobiology, wetlands, and groundwater in the vicinity of Compañía Minera Antapaccay S.A. in 2022 by OEFA, carried out by Professor Bernhard Wehrli:

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Note: Prof. Wehrli also acknowledges the solid work of CooperAcción, Derechos Humanos sin Fronteras, and Instituto de Defensa Legal in their publication ‘Contaminación en Espinar: Causalidad comprobada’ (Sept. 2024), which summarises the main findings of OEFA in a simplified manner and visualises them on maps, which “represents an accurate and fair synopsis of the detailed analysis by the government agency [OEFA]”, according to the expert.