Temporary dam partially fails at Lake Delhi construction site

Work on a new dam at Lake Delhi might be delayed after the failure Sunday of a temporary steel wall in place for construction purposes.

Heavy rains last week, which led to flash flooding in Cedar Rapids and other parts of Eastern Iowa, created what one official called a 'high water flow” on the Maquoketa River, causing the steel construction wall to break away from the concrete wall behind it.

'This is a construction failure while trying to build a dam,” said Pat Colgan, a retired civil engineer who volunteers at Lake Delhi. He called the incident bad luck.

The failure was about 10 feet wide in a 350-foot-long wall, said Steve Leonard, Lake Delhi Board president.

'It's too premature to know any major impact from this,” Leonard said, but he expected any delay in construction would be 'minor.” The next couple of days will reveal more as the site dries up, he said.

The temporary dam was in place to dry up the area behind it, which would allow for a permanent spillway to be built. The new dam will be able to handle much more rainfall, Leonard said.

Beyond construction and recreational use of the area, Leonard said he was not aware of anyone being affected by the incident.

'I doubt if (the water) rose even a foot downstream,” Colgan said.

The National Weather Service estimated the Maquoketa River would rise only 2 to 5 inches for a few hours.

In summer 2010, the dam at Lake Delhi failed, and the lake was drained.

Colgan said the floodwater that caused the dam to fail that year ran between 25,000 and 30,000 cubic feet per second. When the new dam and spillway are in place, they will be able to handle water at 69,000 cubic feet per second.

The failure Sunday at the temporary dam occurred at the farthest point downstream of the east side of the lake near Delhi.

'We're just looking to get the new … spillway built and keep things moving forward,” Leonard said.

The construction was set to be complete by Oct. 23.

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Max Walker contributed to this report.