Environmental News

Blue Earth County up against the clock — and the unknown — in flood repair projects

Water flows in a river
Water in the Blue Earth River flows around the the Rapidan Dam southwest of Mankato, Minn., on June 24 threatening the integrity of the dam, the County Road 9 Bridge as well as a house on the west side of the dam.
Ken Klotzbach for MPR News

Blue Earth County is busy trying to get ahead of the warming weather on several key infrastructure projects — especially the County Road 9 Bridge.

Floodwaters breached round the Rapidan Dam in June last year, also damaging the nearby bridge. Blue Earth County voted to remove the historic Rapidan Dam in August. Work is already underway on replacing the bridge.

County Engineer Ryan Thilges said a temporary causeway and makeshift diversion channel is built. He added officials are watching weather forecasts to make sure needed bridge work is out of the way before the thaw.

“We’re really under the gun to try to get as much of the old bridge out before any possible spring flood conditions,” Thilges added. 

A pillar of a highway bridge
A pillar on the Highway 9 bridge remains exposed, showing the damage that was done to it by flooding in June 2024. Photographed on Oct. 27.
Jackson Forderer for MPR News

The bridge deck is being removed, and the county is in process of finalizing a plan to schedule severing and felling the bridge’s beams. Last summer’s severe flooding on the Blue Earth River breached around the Rapidan Dam and damaged the structure. 

Status of Rapidan Dam removal

Blue Earth County is working with the Federal Emergency Management Agency (FEMA), to continue detailing the damages and developing a cost estimate it would take to return the Rapidan Dam site to its pre-flood condition. 

The exact timeline for the historic Rapidan Dam removal is still highly uncertain, according to Thilges. He’s reluctant to commit to a timeline, even if it’s an estimate. He said there’s too many factors outside of county control including getting the necessary environmental permits and funding.

“There’s such a high variability of probability of things not going exactly how we would anticipate,” Thilges said. “This is somewhat unchartered waters.”

Floodwaters breached round the dam in June last year, also damaging the nearby County Road 9 Bridge. Blue Earth County voted to remove the historic Rapidan Dam in August. Work is already underway on replacing the bridge.