Blue Earth County votes to remove Rapidan Dam; remove and replace County Road 9 bridge

The Blue Earth County Board voted Tuesday to remove the Rapidan Dam and to also remove and replace the nearby bridge.

The project to remove and replace the County Road 9 bridge could take a couple years. Detours have been in place since last month because of safety concerns caused by severe flooding damage. County officials are also working with the U.S. Army Corps of Engineers to restore the Blue Earth River while seeking federal and state dollars for the restoration. 

The bridge had been closed since June. While this specific bridge doesn’t have high-volume traffic, Commissioner Kip Bruender said during the session that it was still important to consider its importance to the region — including the farm-to-market trips and also adding longer commute times for those living in the area while the bridge is shut down.

“My understanding is it’s a road that gets used a lot for crops and getting in and out of the fields and getting grain to the market,” Bruender said. “So, I think that’s probably the bigger weigh-in here.”

In late June, the Blue Earth River overtopped the Rapidan Dam and eroded and cut a new river channel around the west abutment of the dam. More than a century’s worth of sediment pollution build-up was unleashed downstream from the partial failure of the Rapidan Dam. 

Blue Earth County evaluated options to make interim repairs to try to reopen the bridge, but with the damages inflicted to the pilings on the piers and the river channel scouring that continued to erode the riverbanks, the upkeep for repairs was considered financially unfeasible. 

The county has access to about $19.5 million for bridge removal and replacement in County State Aid Disaster Account Funds. Then, the rest can be put back into the fund when federal dollars come through. 

Rapidan Dam’s future

During the flooding, a century’s worth of sediment build-up behind the Rapidan Dam unleashed downstream into the Blue Earth River, which concerned water quality experts and researchers about the environmental impacts the pollution could have on the various ecosystems and wildlife. 

The U.S. Army Corps of Engineers discussed its ecosystem restoration program and possible dam removal and river restoration along with attempting to restore and protect the Blue Earth River in its current condition. As of now, the dam’s structure was still considered to be stable. 

However, the safety and liability of the dam structure worries them. County engineer and public works director Ryan Thilges said it would only be a matter of time before someone is injured or possibly killed if the dam is kept, and it would be difficult to keep people off the dam.

The dam structure also could create an awkward river flow that would require armoring to reduce or prevent the riverbanks from deteriorating further. But, even then, Thilges said he wasn’t confident in those efforts being effective.

“I would anticipate that that’s going to be a continual problem child on that west embankment,” he said. “Trying to protect it and a little bit of a money pit in the long term.”

Commissioners unanimously approved removing the dam, which also included river restoration. They’ll work with the U.S. Army Corps of Engineers to restore the channel post-dam removal. They mentioned gathering stakeholders in the future to talk about the future of the Blue Earth River about creating recreational opportunities, including kayaking and biking around the Rapidan Dam site. 

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