A week before what the Indigenous Krenak people now call “the death of the river,” they say they could feel it coming. The birds stopped singing, the air grew heavy, and an unusual silence settled over their village in Minas Gerais, a southeastern Brazilian state where forested hills give way to the winding Doce River.

Then, on Nov. 5, 2015, the mud came.

A mining dam owned by Samarco — a joint venture between Brazilian company Vale and Anglo-Australian giant BHP Billiton — burst upstream near the town of Mariana, unleashing a torrent of toxic iron ore waste.

It buried the nearby community of Bento Rodrigues and swept down the Doce River valley, killing 19 people and contaminating waterways for nearly 600 kilometers (370 miles) before reaching the Atlantic Ocean.

For the Krenak people, who once relied on the river for food, rituals, and daily life, the damage was not just environmental but spiritual.

"This date, was one of the worst moments for the Krenak people, one of the worst moments of my life," said Shirley Djukurnã Krenak, an Indigenous leader whose community has lived for generations along the Doce River. “We felt the death of the river before it arrived.”

The Mariana disaster poured an estimated 40 million tons of mining waste into the Doce basin, devastating one of Brazil’s most ancient river systems, whose valley has shaped the landscape of Minas Gerais for millions of years.

Ten years later, reconstruction and reparations have dragged on through legal disputes, and the river remains contaminated by heavy metals.

Local communities say little has changed, even as Brazil strives to define itself as a leader of global climate policy while hosting the United Nation’s COP30 climate summit — an event some are skeptical will bring change.

Brazilian President Luiz Inácio Lula da Silva now hopes to cement his reputation as a global environmental leader at COP30 in Belem, at the heart of the Amazon.

Yet the unresolved legacy of Mariana and other recent policy moves reveal the distance between Brazil’s climate discourse and reality, according to Maurício Guetta, legal policy director at the advocacy group Avaaz.

"It would be extremely negative for Brazil, a climate leader, to set an example by approving legislation that effectively abolishes the environmental licensing system, posing serious risks to the population, the environment, and the climate," he said, adding that Indigenous territories are among the world’s most effective barriers against deforestation.

Indigenous congresswoman Célia Xakriabá, who represents Minas Gerais, said the tragedy remains “a crime still in progress.”

She said the Doce River is "still sick."

"The Krenak people always say that this is an ongoing crime. Even as we understand the process of reparation, we recognize there is something you cannot bring back. You can’t bring back the 19 lives or the clean, healthy river."

Xakriabá said the lack of justice for Mariana victims undermines Brazil’s credibility ahead of the summit.

“It’s hard to talk about climate leadership when the state where this crime happened hasn’t even recovered,” she said. “True environmental policy starts with justice for those living the consequences.”

After the 2015 collapse, the state of Minas Gerais weakened its environmental licensing laws — a move Guetta said directly contributed to the Brumadinho dam disaster in 2019, which killed 270 people.

In October 2024, Brazil’s government and the states of Minas Gerais and Espirito Santo signed a 132 billion-reais ($23 billion) settlement with Samarco, the mine’s operator, and its owners, Vale and BHP, to fund social and environmental repairs.

The record deal which will bring the total payment to 170 billion-reais ($30 billion) includes aid for affected communities, but critics say deeper flaws in Brazil’s environmental governance remain.

Guetta said the Mariana disaster showed how fragile Brazil’s system of environmental control is, and instead of learning from it, communities are seeing a process of deregulation.

Brazil’s Congress approved a law in 2023, which restricts Indigenous land claims, and this year passed what activists call the “devastation bill,” which would relax environmental licensing nationwide.

Environmentalists warn both threaten to undermine the country’s own climate goals under the Paris Agreement, the 2015 global pact to curb greenhouse gas emissions and limit global warming.

Now, Brazil’s Congress is also considering a national bill that would further loosen oversight of mining and industrial projects and “practically dismantle Brazil’s environmental licensing system,” Guetta said.

He added that Brazil’s environmental agencies remain underfunded and understaffed, even as mining and agribusiness expand deeper into fragile ecosystems.

Brazil's environment ministry did not respond to a request for comment.

Krenak told The Associated Press that her community will not be attending COP30. She sees the climate summit as distant from the realities faced by Indigenous peoples and full of “greenwashing” and false promises.

Instead, she said, true climate action begins with protecting rivers and forests — and recognizing Indigenous territories.

As COP30 kicks off, many Indigenous leaders share that skepticism but also remain hopeful.

Krenak said she still believes in change is possible and that one day the area's children will able to "drink a glass of water without fear of dying.”

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Associated Press writer Melina Walling contributed to this report from Chicago.

Video produced by Rosa Ramirez and Steven Grattan.

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