Ever since the Upamayo Dam on Peru’s Lake Chinchaycocha was built in 1932, floods have become a frequent occurrence in the area for several months a year. From January to May, entire homes and pasturelands are swallowed whole by water, forcing campesino families to migrate with their livestock to higher ground. But there’s something else in the flooded waters: it’s also contaminated by the Cerro de Pasco mining district upstream.

When they can return in late June, residents say the pastures smell and are unsafe for animals to graze in. But few have a choice; they never received compensation for other lands. So their cattle and sheep that must eat the grass sometimes develop sepsis and die. Others pick up unknown diseases, and farmers find them running aimlessly, almost mindlessly. There have been so many deaths one community had to open a cemetery specifically for livestock.

“When we see that cattle are already sick, we have to kill them to eat them before they die, but we’re poisoning ourselves,” Micaela Espinoza, a campesina farmer from the Chaquinilnioc community in Vicco district, Pasco department, told Mongabay by phone. “It shows on our skin, on our hands. It shows because we are eating an infected animal. But we prefer to kill them to eat them before they die on their own and we lose, because it’s a source of livelihoods for all these families.”

Studies carried out by the National Water Authority show the presence of heavy metals in the water in excess of environmental quality standards. These include lead, copper, zinc, arsenic and mercury. At levels this high, they can lead to neurological problems and death, but there haven’t been any studies yet on whether the metals contamination in the water is linked to the health impacts and livestock deaths that people are seeing. Despite this, farmers are raising the alarm, pointing to the contaminated water as the culprit.

The 53,000-hectare (130,000-acre) Lake Chinchaycocha, also known as Lake Junín, is a protected area and Ramsar wetland in Peru’s Pasco department. It’s the second-largest lake in the country, after the better-known Titicaca, which is the largest in South America. The area is home to a great diversity of flora and fauna, including endemic species found only in Lake Chinchaycocha, such as the giant frog of Junín (Telmatobius macrostomus) and the Junín grebe (Podiceps taczanowskii), both endangered in part due to pollution.

Decades of contamination from the Pasco mining district upstream, hydroelectric power operations, the discharge of urban wastewater, and the overexploitation of resources by local residents have placed a financial and emotional strain on the lives of campesino families who depend on the lake’s resources to survive, sources said.

Peruvian biologist Luis Castillo told Mongabay that although there are no studies directly linking the decline of giant frogs on mining or wastewater pollution, there’s proof that the problems have altered water quality, which can affect aquatic species, such as through bioaccumulation. “No records of frogs have been found in Lake Chinchaycocha recently,” he said. “They are very rare because this habitat is no longer suitable for the species due to the various threats it presents.”

“The issue of pollution isn’t just mining pollution, it’s also wastewater pollution,” Rover Yone Paucar Arzapalo, a prosecutor for the Communal Environmental Surveillance Committee of Lake Chinchaycocha, told Mongabay by phone. “The five districts in the area, all of them, their entire population, receive water contaminated by wastewater, which then enters Lake Chinchaycocha.”

Campesino residents also say the water crisis has impacted campesino customs and culture, as wild native animals such as llamas, alpacas and vicuñas have died from infections or moved away. Maca (Lepidium meyenii), a native plant cultivated in the central Andes for more than 2,000 years for food and as a traditional medicine, as well as native potato species, are also under threat due to pollution in the soils, Angelica Pérez from the Ondores campesino community in Junín, told Mongabay.

Companies with mining concessions in Cerro de Pasco, such as Volcan Compañía Mineria S.A.A., majority-owned by Glencore Perú, and Cerro de Pasco Resources Inc. (CDPR), didn’t respond to Mongabay’s requests for comments by the time of publication. Neither did Peru’s Ministry of Environment and Ministry of Energy and Mines

Causes of the damage

For campesino families around Lake Chinchaycocha, their problems began in 1932, when the Cerro de Pasco Copper Corporation started building the Upamayo Dam. This caused the San Juan River, which flows from the Cerro de Pasco mining district, to redirect water originally destined for the Mantaro River into Lake Chinchaycocha.

The Ragra River, another microbasin that feeds the San Juan River and has essentially become a tailings pond for the Cerro de Pasco’s mining waste, has been described as one of the world’s most contaminated places.

In September 2024, Servindi, an organization that promotes intercultural dialogue related to Indigenous and ecological affairs, identified 48 mining environmental liabilities in the districts of Vicco, Ninacaca, Carhuamayo, Junín and Ondores, 41 of which are located within 20 kilometers (12 miles) of Lake Chinchaycocha.

Citing reports by the Pasco Local Water Authority (ALA) and the National Water Authority published between 2018 and 2023, Servindi said these rivers contain heavy metals, such as lead, copper, zinc, arsenic and mercury, exceeding environmental quality standards.

“There are many mining plants that do not work as environmentally and socially responsible as they should,” Delcy Uscuchagua Carhuaricra, former president of the Communal Environmental Surveillance Committee of Lake Chinchaycocha, told Mongabay by phone. “More than anything environmental because the large and medium-sized mining companies I think have a little more budget in that aspect, but the small ones do not. So, the [large companies] are the most irresponsible because those waters that leach from those plants and go directly to natural bodies of water, they damage and contaminate the environment.”

Overgrazing and the lack of urban wastewater treatment plants in districts upstream have also contributed to the serious pollution issue in Lake Chinchaycocha.

Migration

Since January, the 500-hectare (1,235-acre) plot that Micaela Espinoza farms has been completely submerged by contaminated water. This has happened every year since the dam was built, she said, but the problem has intensified in recent years.

This year, the floods came unexpectedly fast. In a matter of minutes, Espinoza found herself trapped on a shrinking island of dry pasture, along with her parents and some livestock. They tried to rescue as many animals as they could, but the water’s immense power swept many away. They lost six calves and 26 sheep, she said.

“That scene was terrible, the helplessness of seeing your investment and your dreams go away,” she said.

Because of the floods, her family and many others have been forced to take the costly journey to higher ground where they remain until their pastures dry in June. Families travel to communal lands in Vicco where they can stay for an annual fee.

“Material goods, belongings, tents, fences, etc., are transported in carts hired for the transfer, while animals are herded,” Espinoza said. “We currently have to cross a long stretch on foot, and on the highway that connects Canta Huayllay to Vicco there is a lot of traffic, and [drivers] also run over animals.”

When they’re able to return to their lands in June, the pastures smell and are unsafe for the animals to graze in. “There are times when sheep begin to die, and when the [veterinarian] performs an autopsy, they come out with rotten livers, damaged lungs, and undiagnosable diseases,” said community leader Uscuchagua, who also raises livestock.

“That’s why this is practically genocide, because it doesn’t just affect the cattle ranchers,” she said. “All the meat from this area goes to the Lima market. What kind of meat are we sending?”

Cultural impacts

Angelica Pérez, the campesina from Ondores, said the contamination threatens the survival of campesino culture. Years of unclean water in Lake Chinchaycocha have led to the disappearance of native plant and animal species, leading to a decline in traditional foods and clothing.

Wild native animals, such as vicuñas, alpacas and llamas, have disappeared because of the contamination, she said. “Our people here in the area made their clothing with wool from vicuñas and alpacas, which are now generally displaced due to the quality of our soil.”

To preserve the ecosystems and the cultural richness of the area, local residents have reported the issue to local and national authorities. But the latter haven’t done anything yet to address the problem or meet with them, locals say. “There is no real intention to conserve or mitigate impacts in the case of contamination or effects that this reservoir is causing with contaminated water,” Uscuchagua said.

Some community members have focused on small actions, such as the conservation of the giant frog species. “Much of the cultural customs and clothing have been lost,” Pérez said. “But we’re working to recover and revalue that.”

Banner image: Chilean flamingos (Phoenicopterus chilensis) in Lake Chinchaycocha in Junín, Peru. Image by Roberto Elias. 

Citations:

Filiberto Cusiche Pérez, L., & Amparo Miranda Zambrano, G. (2019). Contaminación por aguas residuales e indicadores de calidad en la reserva nacional ‘Lago Junín’, Peru. Revista Mexicana de Ciencias Agrícolas, 10(6), 1433-1447. doi:10.29312/remexca.v10i6.1870

Rodbell, D. T., Delman, E. M. Abbott, M. B., Besonen, M. R., & Tapia, P. M. (2014). The heavy metal contamination of Lake Junín National Reserve, Peru: An unintended consequence of the juxtaposition of hydroelectricity and mining. GSA Today, 24(8), 4-10. Retrieved from https://rock.geosociety.org/gsatoday/archive/24/8/pdf/i1052-5173-24-8-4.pdf

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