For the second time in less than 24 hours, families living along the Tittabawassee River and connected lakes in Midland County were ordered to leave home.

The National Weather Service on Tuesday evening urged anyone near the river to seek higher ground following “castastrophic dam failures” at the Edenville Dam, about 140 miles (225.31 kilometers) north of Detroit, and the Sanford Dam, about seven miles (11.26 kilometers) downriver.

Michigan Gov. Gretchen said downtown Midland, a city of 42,000 about 8 miles (12.87 kilometers) downstream from the Sanford Dam, faced an especially serious flooding threat. Dow Chemical Co.'s main plant sits on the city's riverbank.

“In the next 12 to 15 hours, downtown Midland could be under approximately 9 feet of water," the governor said. "We are anticipating an historic high water level.”

Whitmer declared a state of emergency for Midland County and urged residents threatened by the flooding to find a place to stay with friends or relatives or to seek out one of several shelters that opened across the county. She encouraged people to do their best to take precautions to prevent the spread of coronavirus, such as wearing a face covering and observing social distancing “to the best of your ability.”

“This is unlike anything we’ve seen in Midland County,” she said. ”If you have a family member or loved one who lives in another part of the state, go there now."

Emergency responders went door-to-door early Tuesday morning warning residents living near the Edenville Dam of the rising water. Some residents were able to return home, only to be told to leave again following the dam's breach several hours later. The evacuations include the towns of Edenville, Sanford and parts of Midland, according to Selina Tisdale, spokeswoman for Midland County.

Dow Chemical has activated its emergency operations center and will be adjusting operations as a result of current flood stage conditions, spokeswoman Rachelle Schikorra said in an email.

“Dow Michigan Operations is working with its tenants and Midland County officials and will continue to closely monitor the water levels on the Tittabawassee River,” Schikorra said.

In 2018, the Federal Energy Regulatory Commission revoked the license of the company that operated the Edenville Dam due to non-compliance issues that included spillway capacity and the inability to pass the most severe flood reasonably possible in the area.

The Edenville Dam, which was built in 1924, was rated in unsatisfactory condition in 2018 by the state. The Sanford Dam, which was built in 1925, received a fair condition rating.

Both dams are in the process of being sold.

There were 19 high hazard dams in unsatisfactory or poor condition in Michigan in 2018, ranking 20th among the 45 states and Puerto Rico for which The Associated Press obtained condition assessments.

Flood warnings in Michigan were issued following widespread rainfall of 4 to 7 inches (10.2 to 17.8 centimeters) since Sunday, according to the National Weather Service. Heavy runoff pushed rivers higher.

The Tittabawassee River was at 30.5 feet (9.3 meters) and rising Tuesday night - flood stage is 24 feet (7.3 meters). It was expected to crest Wednesday morning at a record of about 38 feet (11.6 meters).

The heavy rains early in the week also caused flooding elsewhere in the region. In Chicago, water that flooded some areas downtown was receding Tuesday, but Larry Langford, a fire department spokesman, said that he did not expect power to be restored at the iconic Willis Tower for days because the rains caused the building’s subbasements to fill with as much as 25 feet (7.6 meters) of water. The building was closed to tenants and visitors.