How the Midwest Floods Nearly Took Out a Century-Old Dam

The warning from the county government was grim. The Rapidan Dam, a feature of the southern Minnesota landscape for more than a century, was “in imminent failure condition.”

“We do not know if it will totally fail or if it will remain in place,” officials said on Monday as dead trees and other debris piled up at the dam and floods overwhelmed the Upper Midwest.

At one point, a support structure alongside the dam partly failed and gushing waters carved out a nearby cliff. Video footage showed a nearby building collapsing on itself and being sucked into the river. But by Tuesday, the main part of the dam was intact, and water flows were beginning to slow. A worst-case scenario, it seemed, might have been averted.

“The Rapidan Dam, we think, is going to continue to hold up,” Bob Jacobson, the commissioner of the Minnesota Department of Public Safety, said late Tuesday afternoon after state officials flew over the dam to survey the damage. “But there are going to be more assessments in the future.”

Experts said the damage and continuing risk in Minnesota underscored the decaying state of the country’s dams and the dangers they could pose when things went wrong. Many catastrophic floods begin with dam failures, and breaches in recent years in states like Michigan and Nebraska have led to widespread destruction.

With climate change making dangerous weather more common, and the average age of an American dam approaching 60, the problems are only expected to get worse.