A US federal judge on Wednesday awarded a $626 million settlement against the state of Michigan to residents of the city of Flint, whose drinking water was poisoned by lead.

The payment, one of the largest civil settlements in Michigan's history, will mainly go to people who were children at the time of the water crisis in the former industrial city, but will also benefit adults who can prove their illnesses were caused by lead poisoning. 

"The settlement reached here is a remarkable achievement for many reasons, not the least of which is that it sets forth a comprehensive compensation program and timeline that is consistent for every qualifying participant," said US District Judge Judith Levy in her ruling finalizing the amount.

The agreement was first reached in August 2020, after 18 months of tough negotiations. The bulk of the payment will come from Michigan, though a small portion will also be paid by the city of Flint and by an engineering company. 

The tragedy began in Flint -- which became a symbol of social injustice in the United States -- when Michigan's then-governor, a Republican, decided to change the source of the city's water supply from Lake Huron to the Flint River in order to save money. 

Acidic, polluted water from the river corroded the system's pipes, exposing residents to lead poisoning. 

Some 18,000 to 20,000 children lived in Flint at the time. The lead poisoning of thousands of the city's children threatens to have catastrophic health consequences lasting for decades. 

At least 12 people also died from Legionnaires' disease, an infection caused by the initial contamination of the water. 

Many residents of the city continue to drink bottled water to this day, even though the water system is once again fed from the lake and the lead pipes have been mostly replaced. 

For many, the Flint water scandal came to symbolize the country's "environmental racism," a term that refers to the disproportionate exposure of African Americans to pollutants in the air, water or soil.

Some 57 percent of Flint's 100,000 residents are Black, and more than a third live below the poverty line.