MIDLAND • Rising floodwaters unleashed by two dam failures submerged parts of the central Michigan town of Midland on Wednesday, displacing thousands of residents and spreading into a Dow chemical plant in the riverfront city.

By late morning, the company said, floodwaters were confirmed to be "co-mingling with on-site containment ponds" at the sprawling Dow plant, located just upstream from a Superfund hazardous waste clean-up site on the rain-swollen Tittabawassee River.

The National Weather Service warned of "life-threatening" flooding as the Tittabawassee rose to historic levels.

Parts of Midland, a city of some 42,000 residents about 193km north-west of Detroit, were submerged under 1.5m of water before the river crested a few feet lower than expected.

Midland County Board of Commissioners chairman Mark Bone said no injuries had been reported. But the flood posed a major logistical challenge to the authorities already coping with the coronavirus pandemic, and Michigan Governor Gretchen Whitmer called for federal assistance.

Some 10,000 people were evacuated throughout Midland County, Ms Whitmer said, after days of heavy rain caused the Tittabawassee to overflow its banks and breach the Edenville and Sanford dams on Tuesday.

"Experts are describing this as a 500-year event," Ms Whitmer told a news conference after a tour of the flood zone. She urged residents in low-lying areas to seek higher ground.

National Guard troops assisted in moving some evacuees out of harm's way.

At an evacuation shelter inside Midland High School, volunteers and evacuees wore face coverings to maintain social distancing.

REUTERS