An aerial view shows the Tapajos river in Itaituba, Para state, Brazil, January 22, 2022. (Reuters)

One of Brazil's largest clearwater rivers, the Tapajos - one called the "Blue River" - has turned brown.

According to federal prosecutors and environmental activists on Monday, the browning of the Tapajos is most certainly due to mixed mud and sediment as a result of increasing illegal gold mining activities.

Due to its initially pristine condition and clear waters, the Tapajos was called the "Blue River." However, upon a 2019 gold rush that attracted miners to pursue the illegal activity in its vicinities, in addition to Bolsonaro's loosening mining restrictions in the Amazon, the river is polluted.

Using mechanical shovels to destroy trees and dig pits, illegal miners dredged the river, vacuuming the river bed, and mud and water are sucked up in the search of gold.

Apesar de outros fatores contribuem para a turbidez na foz do Tapajós, é inequívoco o impacto da atividade garimpeira ao longo de toda bacia, desde Jacareacanga até #Santarém como mostram estas imagens de satélite analisadas pelo @MapBiomas https://t.co/LqBJmGjwZQ @obsclima pic.twitter.com/gM9cjKhn4K
— Tasso Azevedo (@tassoazevedo) January 24, 2022

The water, described as chocolate-colored, can be seen for hundreds of kilometers through aerial view photographs, flowing through the Tapajos where it meets the Amazon River.

The sediment polluting the water has kept bathers afar from the white sandbanks located in Alter do Chao, lower Tapajos. The sandbanks are a popular resort in the lower Tapajos, which is a tributary that flows 2,100 kilometers to the Amazon.

Nota técnica do @mapbiomas confirma alteração da cor da água em Alter do Chão (PA) pela lama do garimpo no rio Tapajós. As imagens de satélite revelam os afluentes do rio saturados de lama num período de seca. (Segue) pic.twitter.com/aHJNMSyHG8
— André Trigueiro (@andretrig) January 24, 2022

Gustavo Alcantara, a prosecutor, estimated that 7 million tonnes of sediment are dumped into the Tapajos annually by illegal miners, urging federal and state environmental agencies to look into the ways in which illegal gold mining has been polluting the river.

According to MapBiomas, an NGO which tracks land use and deforestation in Brazil, satellite data shows that the increasing change in color of the Tapajos is correlated with increasing illegal gold mining activities in the region.

🚩O aumento da turbidez no médio e alto Tapajós pode ter influência de garimpo e outras alterações de uso da terra que causam desmatamento e expõem o solo. Confira a análise com base em imagens de satélite de alta resolução🛰️ https://t.co/DmLnuDeZPn pic.twitter.com/aTQqRBMePu
— mapbiomas (@mapbiomas) January 24, 2022

"It is reasonable to assume that illegal mining has been one of the main causes of the murky waters because it is all done on tributaries of the river and the sediment flows into the Tapajos," said Cesar Diniz, a MapBiomas geographer. It's a fact: The mining has contributed to the muddying of the Tapajos in recent years," he said.

It's ore or gore

Read more: The Amazon's ongoing colonization is still relevant