Work set to begin to preserve historic dam in southeast Minnesota

Updated: March 14, 6 p.m.

After more than a decade of planning, and lobbying, and waiting, work will soon begin on rehabilitating and strengthening a landmark dam in southeast Minnesota.

The Lanesboro Dam, along the Root River in Lanesboro, was built in 1868 by craftsmen using massive, dry-stacked limestone blocks.

It's known as a gravity-arch dam — one of only a handful of its kind left in the U.S. — and it's a hydroelectric structure, producing enough power to serve about 10 percent of the city's homes.

And it's a scenic focal point for residents and visitors, especially walkers and bikers along the Root River State Trail.

But a routine check of the dam 12 years ago found some deficiencies in the structure. Rather than remove and replace the historic dam, city leaders opted to take the time to secure state funding to restore the dam.

"It is emblematic of our community," said Lanesboro Mayor Jason Resseman. "In a tourist season, there are tens of thousands of people that visit Lanesboro to enjoy the river as well as the bike path system. And I would say a large majority of those people go to the dam and appreciate its aesthetic and what it provides to this unique valley here."

City officials worked with the Department of Natural Resources and the State Historic Preservation Office, and with the Legislature through local Rep. Greg Davids and Sen. Jeremy Miller.

Now, with state funding in hand for the $4 million project, work is set to begin in the next few weeks.

Resseman said some of the blocks will be replaced — using limestone from quarries in southeast Minnesota — and the flood gates upgraded, but most of the improvements eventually will be hidden from view.

"Behind the structure, they're going to put in eight or nine large caissons that will be filled with a dolomite riprap material," he said. "The goal for that is to relieve the hydraulic pressures on the dam itself from the upriver side. No one will really notice a difference of the structure itself once it's done, because everything will be done behind it and under the water level."

The work will be done in stages, with the river remaining open through the summer. Icon Constructors is the contractor. The deadline to complete the project is the end of October.

Resseman said the repair effort has renewed appreciation of the work done by crews that built the dam back in the 1800s.

"I just look at the equipment that's there now, that they're going to use to fix it. And that stuff just towers over what would have possibly been available to the contractors 152 years ago," he said. "So frankly, it's quite impressive that the tradesmen that worked on it and their craftsmanship — that something of that nature was able to stay standing and functional for that amount of time."

A groundbreaking ceremony had been scheduled for Friday, March 13, but was postponed to a future date to be determined.

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