RAPIDAN, Minn. — A dangerous combination came rushing down the Blue Earth River this week; dead tree debris and a lot of water. Storms at the start of summer elevated the Blue Earth River to very high levels, and when the debris accumulating at the top of the Rapidan Dam slowed the flow down, the water found somewhere else to go. On Monday, the west bank of the dam capsized into the river, taking with it an energy substation.
“It's a call that nobody wants to get,” Blue Earth County Engineer, Ryan Thilges said.
However, it’s a call that Thilges was anticipating with the aging infrastructure of the dam that’s been beaten up by weather in the last five years. The 87-foot tall and 475-foot-wide dam future has stood on shaky land for some time. Following the destructive floods of 2019, and damaging ice dams in 2020, Blue Earth County invested time into studies of the clear two solutions to their dam problem: repair or remove the dam.
“Obviously with what's happened today, that’s changed the conversation,” Thilges said.
The county took over the Rapidan Dam from NSP, known as Xcel Energy now, after the floods of 1965.
“It was the only road that went over the river at that time,” Thilges said.
Since then, it’s needed four different repairs to a critical piece of the dam; the apron.
"The importance of the apron is so that we can protect the underlying sandstone bedrock that the dam was constructed on top of. The sandstone the dam was built on is highly erodible," Thilges said.
The studies released in 2021 found it would cost $82 million to remove the dam and $15 million to repair it. Part of the struggle removing the dam is also taking care of the sediment build-up that Thilges says poses an environmental concern. The sediment has accumulated over the century and has filled in the river base up to 60-65 ft, according to county public works employees. It's something that the engineers keep a close eye on.
Meanwhile, in the office, Thilges and the county began the Federal Energy Regulation Commission (FERC) exemption surrender process in April 2023. Federal employees told them it would take roughly 6 months to a year to complete the process that would then shift the overseeing of the dam to the Minnesota Department of Natural Resources.
That process still isn’t complete. FERC officials told Blue Earth County officials that they’re inundated with local governments around the country trying to do the same thing as there are more efficient ways to produce clean energy now.
“We have equated the power that the dam is capable of producing over the course of a year or to is equal to three windmills,” Thilges said.
As people across the country have seen videos of the destruction, it raises the question once again: what will the future hold for the 114-year-old infrastructure?