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A southern Minnesota dam and nearby bridge that almost collapsed last month after a bout of heavy rain and prompted a federal emergency declaration will be torn down, officials said Tuesday.
The Blue Earth County Board of Commissioners voted to remove the Rapidan Dam near the city of Mankato, about 80 miles (130 kilometers) south of Minneapolis, and replace the County Road 9 Bridge, both of which were at risk of crumbling. The officials jumpstarted what will likely be a yearslong rebuilding process as the structural integrity of the dam and bridge remain uncertain.
The Blue Earth River’s water levels rose dramatically in late June and early July after heavy rain pummeled the Midwest for days. While the structures held up in the end, floodwaters forged a new river channel around the dam and cut deeply into a steep riverbank, toppling utility poles, wrecking a substation, swallowing a home and forcing the removal of a beloved store.
With the specter of a future collapse still on the minds of a wary local community, officials said they had to act in the name of public safety. But they are concerned about the bridge closure's impact on local farmers, one of the rural area's primary economic drivers.
“We know that this is a rural community and they use (the bridge) for getting farm to market, and we know the fall harvest is coming up and it's going to be inconvenient," said Jessica Anderson, a spokesperson for Blue Earth County. "But safety has been our priority from day one. And we cannot afford to jeopardize that.”
Vance Stuehrenberg, a Blue Earth County commissioner, said farmers might have to travel upwards of 45 minutes around the bridge to reach their fields.
River waters washed away large amounts of sediment, causing instability to the bridge’s supporting piers, built atop sandstone bedrock. The timeline for rebuilding it is unclear, but Anderson said it would be a matter of “years, not months.”
It was also unclear Tuesday how much the rebuilding will cost. Studies commissioned by the county in 2021 found repairing the dam would cost $15 million and removing it would cost $82 million, but Anderson said environmental conditions have changed since then.
The next step will be securing funding to finance the repairs, which could come from a combination of state and federal sources. The county is working to develop a plan with federal agencies including the Federal Emergency Management Agency and the Federal Energy Regulatory Commission, Anderson said.
A federal disaster declaration was approved for Blue Earth County, and local officials said the additional resources will be critical for rebuilding efforts. But those projects could be complicated by a sensitive landscape where relief efforts can sometimes exacerbate decline, officials have also warned.
Stuehrenberg is also concerned about the impact the closure could have on recreation opportunities near the dam, which is a popular area for bike riding. Minnesota Gov. and Democratic Vice Presidential nominee Tim Walz, who visited the dam in July, is among those who used to ride his bike on a nearby trail.
The Rapidan Dam is over a century old, finished in 1910. While it was built to generate electricity, it has been damaged by several rounds of flooding in recent decades. The dam hasn’t been producing power, as previous floods knocked out that small source of revenue.
There are roughly 90,000 significant dams in the U.S. At least 4,000 are in poor or unsatisfactory condition and could kill people and harm the environment if they failed, according to data from the U.S. Army Corps of Engineers. They need inspections, upgrades and even emergency repairs.
