MINNEAPOLIS — The visuals were stunning: Water from the Blue Earth River surged around a southern Minnesota dam, carrying a shipping container with it as it toppled utility poles, wrecked a substation and washed away part of a riverbank. A home on the edge of the eroded slope collapsed into the river.
Earlier this week, authorities said the Rapidan Dam near Mankato faced an ''imminent threat'' of collapse but later said an abutment had partially failed. The river swelled after an onslaught of rain pummeled the Midwest for days.
On Wednesday, the dam was still intact and there were no mass evacuations. Authorities said the partial failure of the abutment was caused by the recent bout of heavy rain, but a past assessment of the dam revealed it was already at risk. Here are some things to know.
What happened?
Early Monday morning, emergency management workers gave notice that water was surging over the dam. As water flows peaked, debris plugged parts of the structure and the west abutment of the dam partially failed. Conditions around the dam spun a current that was too vicious for workers to cross safely to clear the detritus.
The rush of water destroyed a power station and caused outages for about 600 households, Minnesota Gov. Tim Walz said. Water levels peaked Monday at 34,800 cubic feet per second — the normal flow is 500 cubic feet per second. Those figures make this flood the second largest in the dam's history and the equivalent of once-a-century flooding.
The levels had begun to lower by Tuesday, county officials said.
Water continued flowing around and eroding the west side of the dam Tuesday, officials said. But as overall water levels decreased, they said the prospect of a total collapse was unlikely.