Rapidan Dam near Mankato should hold up

Rapidan Dam, south of Mankato, was still standing Tuesday morning, and county officials expect it to survive flooding that threatened the structure.

“We believe it's intact and will hold,” said Eric Weller, director of emergency management for Blue Earth County. “In the next few days we will have to bring in engineers to look at it.”

A house hollowed out by the river remains, Wellers said, and the water has partly receded. The Army Corps of Engineers was on scene Monday evening. Earlier Monday, officials described the dam, which has not produced electricity in years, as being in danger of “imminent failure.”

Weller said the dam held partly because it was sturdily built, but also because water entering the river bank and rushing around the dam relieved the pressure. The county still can't clear the debris clogging the dam because it's too dangerous, he said.

Officials are scheduled to hold a news conference at 9 a.m. Tuesday to provide an update on the dam, which is owned and maintained by Blue Earth County.

Xcel Energy said Monday evening that it expects power to be restored to hundreds of customers by midnight after flooding washed away an electrical substation. The company's outage map showed no one without power Tuesday morning.

The dam was severely damaged during floods in 2019 and 2020, leading county officials to question whether to repair the structure enough so it could generate electricity again or remove it altogether.

Both options were expensive, with a 2021 study estimating repairs at $15 million and removal at $81 million. The county had no plans to restart the dam because the small amount of potential electricity sales was not worth the cost. Instead, Blue Earth officials decided to relinquish its license to federal regulators and turn over oversight to state authorities before making a decision on whether to get rid of the dam.

In the meantime, Blue Earth said it has conducted routine maintenance and safety inspections, the latest in May being conducted by the Federal Energy Regulatory Commission. That inspection found no major issues requiring immediate action, although it did say there were issues such as concrete cracks and scours that Blue Earth should monitor.