WCCO investigates the state of Minnesota's dams and what's being done to reduce the risk
MINNEAPOLIS — Images of the Rapidan Dam from last month show what a powerful force water can be. A partial failure pushed the Blue Earth River around the dam, taking land and a home with it.
That wasn't the only dam that failed during the historic rainfall and flooding — two others had issues as well. Minnesota is home to 1,162 dams. So how likely is it to happen again?
Across the metro and the state, dams control flooding on waterways, maintain lake levels for recreation and help fish and wildlife. Some are big structures. Others you might miss. Each has a hazard classification from little consequence to catastrophic.
"It's in the sense of a hypothetical breach of the dam, what would happen, what are the consequences of that breach?" Jason Boyle, state Dam Safety Engineer for the Department of Natural Resources, said.
Boyle says there are low, significant and high hazard dams, like Kings Mill in Faribault.
"With a high hazard dam the risk of dam failing would be potential loss of life," Boyle said.
There are 55 high hazard dams in Minnesota, from Elk River to Burnsville to Cannon. The DNR regulates about 30 of them, inspecting each high hazard dam each year.
"We're looking for things that might be different than the last time. We're there new areas of seepage, concrete that has deteriorated further, new cracks," Boyle said.
Every dam has a condition. Lake Bronson in Kittson County is the only high hazard dam in the state in a poor condition — the most vulnerable to failure.
"It does not have the capability to pass that extreme event," Boyle said.
The state secured $24 million in funding to replace the dam to protect the community downstream.
Historically, the state has seen dams fail when it's not expected.
There have been 112 failures since the turn of the 20th century, mainly on low hazard dams. Of those, 41 have happened since 2000.
Most notable, according to Boyle, is the Shady Lake failure in Oronoco in 2010. Floodwaters caused it to fail, which took out a section of the bridge.
"Those are unique circumstances. They do happen, and that's why we have to remain diligent all the time to monitor those things," Rice County Engineer Dennis Luebbe said.
Luebbe explains it's up to the owner of a dam to maintain it and make repairs. Kings Mill in Faribault is a high hazard dam in fair condition. It's owned by Rice County.
"Anytime I think a dam would fail partially or catastrophically would have negative downstream consequences," Luebbe said.
Luebbe says the county follows state requirements, having an Emergency Action Plan should something happen — because time is critcal.
David Kral's family owns the Hardware General Store and has lived next door and downstream for decades. He's considered what could happen if the dam were to fail.
"Well, we had concerns about it that you know if it did fail, you know, it would affect a lot of people," Kral said.
He says he grew more wary after seeing the partial failure at the Rapidan Dam last month, but say he won't make changes.
"I don't want to go anywhere. I've been here too long now," Kral said.
Boyle inspected the Kings Mill Dam while WCCO was there.
"They've got some debris that got caught up in the right gate. Looks like a large tree got wedged in on top of the gate," Boyle said.
Debris the county says it will remove so it doesn't create a bigger problem.
Boyle says he's comfortable with the current state of Minnesota dams.
"It's about health, safety and welfare of the public and that's our primary goal is to make sure that's maintained," Boyle said.
There are more than 70 dams on a priority list in need of some level of repair. The projects are currently unfunded.
Click here to see what dams are in your area.
