It was the fourth such environmental disaster in a year, following floods in July, September, and November that killed 75 people in total.

The flooding statewide has surpassed that seen during a historic 1941 deluge, according to the Brazilian Geological Service. In some cities, water levels were at their highest since records began nearly 150 years ago, the agency said.

On Thursday, a dam at a hydroelectric plant between the cities of Bento Goncalves and Cotipora partially collapsed and entire cities in the Taquari River valley, such as Lajeado and Estrela, were completely overtaken by water. In the town of Feliz, 50 miles (80km) from the state capital, Porto Alegre, a massively swollen river swept away a bridge that connected it with the neighboring city of Linha Nova.

Operators reported electricity, communications and water cuts across the state. More than 23,000 people had to leave their homes, according to the civil defense agency.