Historic dam faces changes

The engineers art to the right shows one proposal for removing the current dam. This would affect water levels.

Removal will lower upstream water, cause faster flow downstream

The history of the Flandreau dam dates back to 1881 when a grist mill needed the power of water to operate.
That first dam was wooden and in 1946 was replaced with a new concrete dam that still controls the Big Sioux River today.
But the lifespan of the bridge may be coming to an end, as city officials look at ways to eliminate the dam in an effort to make it safer and open up additional recreation on the river, they say.
But first, the city needs buy-in from other government agencies, the Flandreau Santee Sioux Tribe and local residents on an estimated $1.5 million plan to remove the historic structure. A low estimate is $1.28 million, while a high estimate is $1.96 million.
“This conversation is going to continue, and we hope to have public engagement with us as we move forward with a decision,” Mayor Dan Sutton said at a March 15 online city council meeting with Barr Engineering. The public meeting was attended by several residents, the county council and engineers through a Zoom call.
“The over goal is to try to create safer recreational opportunities for the general public to utilize that area,” Sutton said. “No decisions are near being made on that.”
Barr’s design as presented to the council is a starting point.
“It’s a much broader conversation yet, but we have to start somewhere,” Sutton said.
The firm’s plan calls for complete removal of the dam, which has been called a death trap for anyone who falls in the water and gets caught in its hydraulic roll. Instead of the dam, the river would have four J-hooks, constructed out of filter rock, riprap and boulders, between the dam site and the Crescent Street bridge, which also is planned for removal.
The fate of the dam is a discussion that has been going on for at least six years, but the plans are finally being designed by engineers, who had to wait until water levels were low enough to survey the area.
The plan, one of five the city chose to see as a 30-percent design, will not only imprve safety but will create more fish habitat and an exciting area for paddlers, said Ron Koth with Bar Engineering.
The removal of the dam under the proposed plan would not only lower the water level at the dam site dramatically but would lower water levels in the city park and at the golf course by several feet, at times, the proposal showed. Water at the dam would be about 9 feet lower.
“The lowering will be noticeable,” Tom MacDonald, with Barr, said.
Anglers are attracted to that area now because fish congregate below the dam. Paddlers use the area too and portage around the dam.
“When the dam is removed, the river will be flowing a little bit faster,” he said. “We feel it would be prudent to protect the lower parts of the riverbank. The upper banks that are well covered with trees, we would leave them alone.”
The drop in water levels at the park and golf course concern Alderman Brad Bjerke. While it might make it less likely to flood, it could take away from recreation by compromising the flow of the river there.
“There’s extreme angst on what fishing will be compared to what it is now,” he said. “There are a lot of children with the campers down there that fish that. That’s part of the fishing that probably shouldn’t be overlooked.”
The city council has the restoration of the area around the dam on its priority list of Capital Improvement Projects. The tribe also is working on what could be put in place once the Crescent Street Bridge is removed.
The biggest questions at the dam are how to make it safe while preserving recreation, how much the project will cost and whether the city and any partnering agencies can afford it, Sutton said.

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