Flooding at Rapidan Dam changed a river, lives and recreational area

MANKATO – Every few weeks, David Hruska and his family return to their old home beside the Blue Earth River. They walk along the riverbank near the Rapidan Dam, take pictures, and relive the memories of a life abruptly upended when flooding last year destroyed their house and their cherished Dam Store Café.

“It’s home. It always will be home,” Hruska, 45, said.

But the home he knew is gone, as is the river where he and his father fished their entire lives. The area near the 115-year-old Rapidan Dam, once lauded as one of southern Minnesota’s prettiest stretches of river, drew kayakers and canoers who capped their trips with pie at his family’s café. Now the river is choked with sediment, fishing holes are filled with silt, and the water is so shallow that even the way it sounds has changed.

“I don’t think in my lifetime I’ll ever see it back to the way it used to be,” Hruska said.

Nearly a year ago, the nation watched dramatic images of the Blue Earth River, swollen by rain, outflanking the west edge of the Rapidan Dam, chewing through soft sandstone bluffs and sending the Hruska family’s house tumbling into the raging water.

Lessons from the flood are still settling in for the people whose lives were upended, for the county officials left to manage a damaged dam and bridge, and for the scientists studying a river still in flux.

For Phillip Larson, an earth science professor at Minnesota State University, Mankato, the year since the flood has provided a rare, if sobering, chance to witness the river change through a process that usually unfolds over centuries.

“This is a very unique situation for us as geoscientists,” Larson said, “to be able to study a river that’s experiencing this dramatic change and being able to monitor that change in real time.”

Data from drone flights over the dam provides numbers on how much last year’s flooding changed the river. The river has carved a new path, its west bank shifting about 275 feet in the initial days of the flood.

The 87-foot-tall dam was built on erodible sandstone bedrock in a flood-prone area, bedrock the floodwaters scoured away last year. This eroded an estimated 217,377 cubic meters of earth — 87 Olympic swimming pools’ worth. By March 2025, erosion increased by another 20 Olympic pools’ worth.

And the reservoir, once held back by the dam, unleashed an estimated 1.5 million cubic meters of sediment.

The riverbanks are still eroding, dumping more sediment into the river and changing its ecosystem, Larson said. The water is not as deep anymore, and his team has found trapped fish in shallow pools, some visibly damaged from rubbing against the riverbed.

Larson has lived in Mankato for 12 years, and in years past he said he’s often biked to the Dam Store for a piece of pie. He said seeing the river now is “shocking … like you’re on a moon landscape or something.”

For Blue Earth County officials, the lessons began with a 1:30 a.m. phone call on June 24, 2024: The Rapidan Dam was in trouble. Eric Weller, county emergency management director, said that as the sun rose that morning, it revealed the sheer extent of the crisis.

“This was catastrophic,” Weller said. “There was no doubt about that, and this is gonna be a long, long-term recovery.”

Logs and debris plugged five steel gates at the dam. Without debris, the dam should have been able to clear the water, but instead the river, seeking a path, carved a channel around the dam’s edge.

The initial days were spent in crisis mode, Weller said, battling not just the river but also a deluge of misinformation and rumors of an impending “wall of water.”

A Federal Energy Regulatory Commission report on what happened at the dam and what could have been done better is expected to come out soon.

Nearly a year after the flooding, the county is mired in what Weller calls a “likely decadelong process.”

The County Road 9 bridge, its foundations fatally scoured, was demolished in February. Design for a new bridge is underway, with construction hoped for late 2026 or 2027.

The County Board voted to remove the dam last year, but the path toward receiving funding for that is a bureaucratic labyrinth involving an alphabet soup of federal and state agencies.

“We’d love to be taking the dam out and putting the river back already,” said county engineer Ryan Thilges. “But unfortunately due to federal environmental permitting and all the processes that are in place, we can’t just go in and do that.”

While the county is aware of ongoing erosion, stabilizing the riverbanks will be complicated until the dam is removed, Thilges said.

The possibility of more intense floods keeps Thilges up at night. Floods have been getting more frequent and more intense — 2024’s was the second largest on record, 2019’s the third largest. “That’s very concerning,” he said, especially if the dam site is vulnerable during the lengthy repair and removal process.

But for now, success is measured in increments: “First and foremost it’s a success that nobody got hurt,” Thilges said. “Secondly, the bridge didn’t collapse.”

For Hruska, flood lessons are deeply personal. Hruska said he thought he and his family would live near the dam forever. He and his sister Jenny Barnes grew up there after their father, Jim Hruska, bought the Rapidan Dam Store café in 1972, and their mother is buried in a cemetery nearby.

The house where he grew up fell into the river on June 25. But that didn’t bother him as much as losing the café.

“The Dam Store was so unique,” Hruska said. “I took that the hardest when we lost that.”

The family was heartbreakingly close to saving the café. They found a contractor willing to move the building to higher ground. But then it rained, and the ground beneath the café became even more unstable. On June 28, the county bought the building and demolished it.

Hruska and his family moved in with his sister, and they reopened the café in a downtown Mankato location in November.

On a recent morning, the familiar clatter of dishes and the sizzle of burgers on the griddle filled the new location. Photos of the old store, the dam and the flood adorn the walls. “We don’t want people to forget about it,” Hruska said.

Hruska still hopes to return the Dam Store to its old location, perhaps in three to five years. But he says he now accepts that the future can change as rapidly as the Blue Earth River did.

“We realize now more than anything that you never know what’s going to happen,” Hruska said. “You just gotta be positive, and … look for a better day ahead.”