Merton Millpond Dam failure potential after heavy rain; concern rises

Dam concerns in Merton

There are serious concerns about the structural integrity of the Millpond Dam in Merton.

MERTON, Wis. - Officials in Merton are monitoring the Millpond Dam after a sinkhole prompted a Level 2 emergency declaration, indicating a potential for dam failure. 

What they're saying:

The village says the dam structure is solid, but the ground and parking lot around it are a concern.

"They are saying our dam, the structure itself, is solid," Village President Ron Reinowski said. "We’re more concerned about the ground around it and the parking lot we’re standing on."

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The Wisconsin Department of Natural Resources said the sinkhole affects only the retaining wall, which is not integral to the dam. Leaders say a steel wall extends nine feet from the bottom of the dam into the ground and 20 feet in each direction.

But there’s a surge coming.

Rosie Meyer lives on Bark Lake. Six miles upstream, it’s still flooded.

"You drive out here, and it doesn’t look like there’s 10 inches of rain fell. Because it’s all sitting in Bark Lake," she said. "It’s just nuts."

Big picture view:

The lake feeds the Bark River, which comes to the Merton Millpond Dam. Village officials say the lake’s outlet to the Bark River is clogged, creating the risk of a surge downstream once it clears.

"We need to make sure that we can handle that rush that comes down, that’s going to fill this up, more," Merton Fire Chief Josh Paral said. "But, at the same time, we’re going to be letting a lot more out then."

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The dam has two sides; one side’s gate can let more water out of the dam.

From Merton, the Bark River also runs through Hartland, Delafield and Dousman before reaching Jefferson County. 

For now, Millpond is being kept lower than normal to prepare for a surge, while the DNR assesses where the excess water could end up.

Some will flow into possible pockets along the river. But some of that surge will make its way to Millpond Dam.

SKYFOX: Bark Lake flooding, Millpond Dam concerns in Waukesha County

SKYFOX captured the flooding as seen at Bark Lake in Waukesha County. There is also growing concern at the Millpond Dam in Merton.