LAX regulations and chronic short staffing made the devastating collapse of a dam in south-eastern Brazil all but destined to happen, experts and legislators say.

The failure of the dam holding back iron ore mining waste unleashed an avalanche of mud that buried buildings and contaminated water downstream.

At least 115 people died in the collapse on January 25, and another 248 people remain missing.

One of the cruellest aspects of the tragedy in Brumadinho is that it has happened before: in 2015, mining dams burst in nearby Mariana in what is considered Brazil’s worst environmental disaster.

In the three years since the Mariana rupture killed 19 people, the regulation of the industry has reduced, not increased, in Minas Gerais state.

“It felt like it was just a matter of time before something bigger would happen,” said Josiele Rosa Silva Tomas, the president of the Brumadinho residents’ association.

Problems that existed when the dams in Mariana burst have persisted, like dramatic short-staffing, while a new law has reduced the say of environmental groups in the project licensing process.

Environmental groups accused the previous Congress and president of rolling back significant protections, and many expect further weakening under president Jair Bolsonaro, who has said environmental regulation hamstrings several industries, including mining.

But the politics that contributed to the collapses in Minas Gerais are much more local. For centuries, the mineral-rich state has revolved around the mining industry – its name, given by Portuguese colonisers, translates to “General Mines”.

“Minas Gerais has a centuries-long history of being lenient with the mining sector. It’s cultural,” Joao Vitor Xavier, a state deputy, said.

“The industry creates a discourse where they dangle jobs and economic growth in front of people, but they put profit over safety.”

The CEO of Vale SA, which owned and operated the Brumadinho mining complex, acknowledges their regulatory measures fell short.

“Apparently to work under the (current) rules has not worked,” Flavio Schvartsman said during a press conference several hours after the dam breach.

Officials have said they don’t yet know why the dam collapsed.

Arrest warrants have been issued for five people responsible for safety assessments of the dam, including three Vale employees.

The Mariana collapse unleashed nearly 60 million cubic metres of mining waste into rivers and eventually the Atlantic Ocean.

While its environmental impact is considered the worst in Brazilian history, Brumadinho has already far surpassed its death toll.

In the wake of the Mariana tragedy, Minas Gerais was already struggling to implement what regulation it had: a 2016 audit found the state had only 20% of the staff needed at the agency charged with regulating mines.

In 2015, the state approved a new process for licensing mining projects. It shifted responsibility from a board that included several environmental organisations to the state environmental secretary, who created a new board with a majority of participants favourable to mining industry interests.