Minnesota’s Rapidan Dam in ‘imminent failure condition’ after heavy flooding, residents warned

A dam in south-central Minnesota failed Monday morning, raising fears of flooding among area residents.

Citizens in low-lying areas of the Minnesota River Valley have now been told to evacuate — as officials continue to monitor whether the Rapidan Dam will fully yield.

The structure is located on the Blue Earth River, where it has stood for the past 114 years.

Debris began accumulating there on Sunday due to abnormally high rainfall, putting the more than a century-old barrier “in a state of imminent collapse.”

By 10:36 a.m., the river had eroded the earth around the west side of the dam near the south side of Mankato to the point where water was pouring over the concrete, now endangering the city of 45,140.

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Citizens in low-lying areas of the Minnesota River Valley have been told to evacuate — as officials continue to monitor whether the 114-year-old dam on the Blue Earth River will completely collapse

In an alert issued Monday as images showed parts of the dam in ruins, Blue Earth County Emergency Management stated: “We do not know if the dam will fail completely or if it will remain in place.

“However,” the agency added, “we determined that it was necessary to issue this notice to advise downstream residents and the appropriate regulatory authorities and other local agencies.”

Meanwhile, debris dislodged by the water flow continues to flow downstream as power outages have also been reported in surrounding areas.

The Blue Earth County Sheriff’s Office said Monday morning that they were aware of such outages and were working to resolve them, but did not provide details on the number of homes affected.

In their own statement, the National Weather Service described how the failure will cause the portion of the river that cuts through Mankato to fall just below major flood status Tuesday morning.

Twenty other cities – such as Fairmont – are also in the flash flood radius, as water has already washed away much of the dam, raising questions about its structural integrity for years.

Gov. Tim Walz and state emergency officials cited this type of investigation when issuing their own statement Monday morning, as nearby roads

“I know the structural integrity of the dam has been a question for a long time,” Governor Walz said of the longstanding structure, built in 1910 by the Ambersen Hydraulic Construction Company.

Officials are warning residents downstream about the risk of wayward debris and rising water levels, which have already washed away part of the dam and several buildings nearby

Residents of Le Sueur County – of which there are more than 28,000 – are being told to evacuate, especially those living in low-lying areas of the river valley

“Removing the dam is a question that has been discussed for a long time.”

He and other officials are warning residents downstream about the risk of wayward debris and rising water levels, which have already washed away part of the dam and several buildings nearby, photos show.

They are telling residents of Le Sueur County – of which there are more than 28,000 – to evacuate, although the warning was aimed more at those in low-lying areas of the river valley.

Parts of Mankato near the Blue Earth River meet this criterion and are expected to bear the brunt of the floods as they reach a predicted tipping point on Tuesday.

Until then, the NWS has issued a flash flood warning for thousands of people living downstream until 4:30 p.m., although no official evacuation order has been issued.

ric Weller, Blue Earth County’s emergency management director, told the Star Tribune by phone late Monday morning that the “dam could fail” and that anyone deemed at risk had been notified.

He added that despite the lack of an official order, several people have already left their homes after the dam was ‘breached’, and anyone in danger has already been urged to consider leaving.

Parts of Mankato near the Blue Earth River meet this criterion and are expected to bear the brunt of the flooding as it reaches a predicted tipping point on Tuesday.

Again he gave no details, but said those who were not warned were unlikely to be in danger, although things could change when the scale of the crisis is measured again on Tuesday.

Officials, meanwhile, are preparing for the worst as swelling water cut through the west side of the dam on Monday, causing debris to pile up in the river.

Authorities are monitoring the bridges for County Road 33 and County Road 90 to see if debris will continue to pass downstream and harass motorists, ready to close the roads if necessary.

Footage filmed overhead shows homes on the west side of the dam perilously close to the water flow, which at the time of writing is still sending more water than normal downstream toward cities like Mankato, to name just a few. silent from the rubble.

Pieces of provincial infrastructure are among the debris currently being sent downstream, officials said – as they continue to monitor events.

This is a development story; come back for more updates.