- Mongabay Latam flew over the basins of the Nanay and Napo rivers, in Peru’s Loreto region, and confirmed mining activity in this part of the Peruvian Amazon.
- Environmental prosecutors say that there may be even more boats and mining machinery hidden in the ravines of both rivers.
- During the flyover, authorities confirmed the use of not only dredges, but also of mining explosives, which they say destroy the riverbanks.
- Almost 15,140 liters (4,000 gallons) of fuel have been confiscated from illegal mining networks around the Nanay River in the last two years, but authorities’ efforts seem insufficient.
On a small airplane, José Manuyama, a professor, frowns and shakes his head with anguish while thousands of feet below, five dredges operated by illegal miners excavate the Nanay River Basin, in the Loreto region in the Peruvian Amazon. “They are like enormous leeches in the water,” said Manuyama. The plane has begun its second hour of the flyover above the Nanay River and, so far, the people on board have seen about 40 dredges. The Nanay is surrounded by shiny riverbanks with an ochre hue, a result of the mercury used by the illegal miners to separate gold particles from other sediments. River mining is prohibited by Peruvian law.
For Manuyama, the president of the Committee for the Defense of the Water of Iquitos, the situation is very disheartening. He says that seven years ago, the Nanay was a clear river, but the beginning of the COVID-19 pandemic brought an increase in the mining rafts that have now given the river a milky appearance. Manuyama, a member of the Kukama community, is a social studies professor and is one of the 15 people on the plane, which is now flying over the Napo River. From the air, the orange pipes coming out of four dredges resemble the tentacles of a gigantic animal drilling into the river basin and disturbing the edge of the forest.
Along with Manuyama are the prosecutor from the Specialized Prosecutor’s Office in Environmental Matters of Loreto (FEMA Loreto), Bratzon Saboya, and the coordinator of the Specialized Prosecutor’s Office in Environmental Matters of Peru, Frank Almanza. Both are convinced that, after the last monitoring operation, conducted two months ago, the crisis in the Nanay River has worsened.
“In the first week of August, we destroyed 20 dredges and, days later, seven more within two sections of the river. We see that now the miners have returned to those same places,” said Saboya. A team from Mongabay Latam was also part of the flyover, in addition to Herman Ruiz (the director of the Allpahuayo-Mishana National Reserve), representatives from the Norwegian and German embassies, and members of the Foundation for Conservation and Sustainable Development (FCDS), which managed and led the aerial inspection.
The greatest concentration of mining dredges in the Nanay River Basin is between the communities of Puca Urco and Alvarenga. Video by FCDS Peru.
Although the contamination from mining is evident along the entire Nanay River Basin, the presence of machinery for gold mining begins at the Indigenous community of San Juan Ungurahual. The most tumultuous stretch is between the Indigenous communities of Puca Urco and Alvarenga (the last community in the river basin), which are five hours apart by boat or 25 minutes apart by flying. In some areas, the dredges are few and far between, but there are places on the river where there are up to five of them. These are the points in the river basin that have accumulated the most metal, and they are exploited daily until that metal is completely gone.
According to investigations by FEMA Loreto, Puca Urco is currently seeing a continuous increase in bars used by illegal miners, where undercover prostitution is often practiced. This means that Puca Urco is experiencing a social crisis and safety concerns similar to those in the past few years in some Indigenous communities in the basins of the Cenepa and Santiago rivers, in the Amazonas region. These issues even extend to Huaman Urco, on the banks of the Napo River. The three-hour flyover showed that this community is surrounded by mining rafts that have been operating in the Nanay River.
Advancing and ascending
The FCDS has documented that, between 2021 and 2025, 939 dredges have operated in various places in Loreto. Of this total, 688 were recorded in 2025 alone. The report by the FCDS indicates that illegal mining is present in 24 rivers and ravines in Loreto and that it has affected 29 Indigenous communities in this region. A total of 362.25 hectares (about 895 acres) have been affected by illegal mining. Saboya views the situation as increasingly dismal. Each additional inspection reveals yet another mining method that intensifies the devastation and crime.
“With this flyover, we have also managed to confirm the use of mining explosives, which are distinct from dredges. They have a set of pulleys, suction pumps and metal tubes, which replace the usual hoses. These tubes enter the basin and are slowly destroying the riverbanks,” said Saboya as he got off the small airplane.
Saboya described the constant activity of the groups of miners operating along the banks of the Nanay River, already affecting the area’s vegetation. Sections of the forest appear to have been eaten away in several places in the river basin, but the amount of deforestation has not been quantified yet. The FCDS says that, for now, this is an initial effect, since the mining activity is mainly concentrated within the river.
The counting and recording the coordinates of the mining sites is exposing a critical environmental situation in this part of the Peruvian Amazon. However, the current scenario may actually be even worse. These may not be a complete picture of the damage in the Nanay and Napo river basins. According to prosecutors, in response to increased controls, the illegal miners may have hidden several dredges and explosives in the ravines and streams.
Last February, FEMA Loreto found during an aerial survey 65 machines for alluvial mining in the same areas analyzed during this flyover. “We’ve now found more than 45, but it is very likely that there are more hidden,” said Bratzon Saboya.
Relentless mining activity has covered the Nanay River with an ocher hue, believed to be a product of mercury contamination. Video by FCDS Peru.
The growth of the illegal mining industry in Loreto is not only evident in the increase of dredges or explosives in the region’s rivers. Almanza said that the motors brought to the river are increasingly large and, as a result, the devastation they cause is greater. Almanza emphasized that another factor is the migration towards mining by some gangs that were previously dedicated exclusively to drug trafficking.
While walking through the Francisco Secada Vignetta International Airport in Iquitos, Peru, Almanza explained that, currently, the production and sale of cocaine is generating high costs for drug networks, which means it is less profitable than before. “Also, cocaine has to compete with other types of drugs, and their sale is a more prosecuted crime. Criminal organizations have seen that illegal mining is an activity where one earns much more at lower costs; it is less punished and there are fewer institutions that pursue it,” said Almanza.
Almanza said that illegal mining offers the most favorable scenario for criminal groups. This destructive industry’s mechanisms are driven by sophisticated technology and equipment. In addition to large machinery for alluvial mining, prosecutors’ investigations have detected that the groups of illegal miners along the Nanay River also use drones to determine whether an operation is in progress and even use satellite Internet service. “The conditions are there for everything to worsen; the government has to make it a priority to combat this scourge,” said Almanza.
According to information from FEMA Loreto, each gram of gold extracted from the Nanay and Napo rivers is worth about $87.50 if sold in the communities in either of the two river basins. A gram of gold sold in Iquitos, the capital of the Loreto region, is worth up to $97. The record-breaking price of gold is another reason why Almanza also believes that illegal mining is absorbing members of several criminal groups. Before leaving the airport terminal, Almanza told Mongabay Latam: “There are fears that an ounce [of gold] could reach a value of $5,000 this year.”
In August 2025, FEMA Loreto destroyed 20 dredges operating in the Nanay River. The miners have since returned to those same sites. Video by FEMA Loreto.
Latent risk
In June 2025, the Center for Amazonian Scientific Innovation (CINCIA) and the Peruvian branch of the Frankfurt Zoological Society (FZS Peru) conducted a hair analysis on 273 participating residents from seven communities located in the Nanay and Pintuyacu river basins. They found that 79 percent of participants had mercury levels that exceeded 2.2mg/kg, which is the limit recommended by the World Health Organization. The results, which indicate that there is a medium- to high risk among the participants, are associated with the consumption of fish containing this heavy metal. The Pintuyacu is a tributary of the Nanay, which is the main source of drinking water for the city of Iquitos.
That percentage is another indicator of very high pollution in the Nanay River.
The contamination does not only affect the Indigenous communities in the river basin, according to Manuyama. “The [fish] black prochilodus, dorado [and] tiger shovelnose catfish, which contain mercury, are also eaten in Iquitos. We still cannot identify exactly where the heavy metal contamination is in the city,” said the activist, who has been recognized as one of 17 defenders of the world’s rivers by the Lewis Pugh Foundation.
Manuyama describes the Nanay as a beautiful river: its unique basin spans 600 kilometers (about 373 miles) of diverse endemic rainforest. It is considered fundamental for more than 500,000 people in the Peruvian Amazon. But he also warns that this natural beauty, which is a hosts “extraordinary ecosystems,” may soon become a dumping ground. According to the professor, that is directly related to the government’s role. “The Nanay is easy to navigate; it has an entrance with control posts. But [illegal mining] happens with complete impunity. The authorities do not fulfill their role,” said Manuyama.
Manuyama said that the illegal miners cannot move machinery or supplies to the gold mining sites without being seen by authorities and other people: “What this crime does is deepen the corruption in the government. Illegal mining does not just mean the plundering of nature, but also of institutions.”
Still-insufficient efforts
From the Nina Rumi port, in Iquitos, it takes at least two hours by boat along the Nanay River to reach the Yarana surveillance and control post. A speedboat goes through the lush vegetation surrounding the intense brown river basin. That distant trace, seen from the small plane, meanders through the rainforest. A team of park rangers from Peru’s National Service of Natural Areas Protected by the State (SERNANP in Spanish) and nine police officers, who rotate shifts every 20 days, conduct surveillance from a two-story wooden structure. From there, they must be able to see the passage of any boats filled with mining supplies. If they spot one, they begin operations to confiscate items and make arrests.
Approximately 50 large drums and cylinders hold almost 4,000 gallons of fuel seized from several groups of miners who had left Iquitos, headed for Puca Urco and Alvarenga. There are also rolls of carpeting, which illegal miners use to process and extract gold particles from the mud and rocks in the Nanay River. There are tubes and hoses for suction, motors for small boats and other engines to provide energy, boats, rafts and other elements used for mining. These are some of the items that authorities have confiscated from along this section of the river in the past two years.
“But we also know that there are alternate routes that illegal miners use to transport machinery and chemical supplies: sacaritas [narrow, small channels], where they slip past surveillance,” said Saboya while looking over the devices and tools confiscated from the illegal miners.
Prosecutor Saboya said that during the raid in early August, with members of the Peruvian Navy’s Special Operations Force (FOES), in the Nanay and Putumayo rivers, he found military attire very similar to the clothing worn by Colombia’s Residual Organized Armed Groups (GAOR) and Brazil’s Comando Vermelho.
They were tied to two criminal organizations (the first being GAOR, a dissident group from the Revolutionary Armed Forces of Colombia [FARC in Spanish]), which operate on the Peruvian-Colombian border and the Peruvian-Brazilian border. Branches of either of these large criminal networks, which are present along these borders to direct drug trafficking and illegal mining, may have extended into this section of Loreto.
“The threat is ongoing here. We’ve suffered two attacks at the surveillance posts when the police were not present. In Yarana, in 2023, and this year at the post in Aguas Negras. The park rangers were attacked by alleged miners. They come to dismantle the post,” said biologist Herman Ruiz Abecasis, the director of the Allpahuayo-Mishana National Reserve, to Mongabay Latam.
What SERNANP and the Peruvian National Police are attempting to do is to cut the flow of supplies for mining activity and, as part of that work, they aim to keep risks away from the natural area, which spans 59,000 hectares (about 145,792 acres, or 228 square miles). This area extends from the estuary of the Aguas Negras ravine to the estuary of the Kuraka ravine. According to Ruiz, 89 percent of the land in the Allpahuayo-Mishana National Reserve is protected.
That situation is very different from that of the Alto Nanay-Pintuyacu-Chambira Regional Conservation Area, which is nine hours by boat from the Yarana post. There, according to park rangers, the dredges have almost reached the riverbanks. These are the mining rafts that, according to their coordinates, corresponded to the community of Alvarenga.
In the dim light emerging from the forest on this night, José Félix Olazábal, a Peruvian National Police officer in charge of the surveillance post, pointed to the opposite bank of the river and said that not long ago, he and his staff had identified signs left by the miners to mark a route. “Right now, they are hiding in the ravines, but maybe later they’ll try to pass through the route that they’ve marked,” said Olazábal. “That’s how this is here,” he added, without looking away from the Nanay.
Banner image: The mining dredges installed along the Nanay River have begun to consume sections of forest. Image courtesy of FCDS Peru.
This article was first published in Spanish here on Oct. 2, 2025.
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