Construction and mussels study begin at Coralville Lake

Crews will begin fixing a structure that's more than 50 years old Tuesday morning.

After years of wear and tear, and the 2008 flood, the Army Corps of Engineers says the Coralville dam needs some repairs.

Over time, the concrete on the dam's stilling basin has eroded. That's the concrete structure that helps break up the force of the water flowing out of the dam. It prevents banks from washing away downstream.

Crews plan to place steel plates on the stilling basin to repair the concrete. Without the fixes, lake officials say there could be the potential for the dam's integrity to suffer.

For days, the Army Corps of Engineers has been slowly reducing the amount of water released through the dam.

"The gates in the control house will be almost closed. There will be some leakage around the gates, we have to get down to a flow of 300 cubic feet per second to allow the work to be done,” said Coralville Lake operations manager John Castle.

The Iowa River will temporarily be about three to five inches lower than usual because of the construction work on the dam. Some excited scientists are taking advantage of the lower Iowa River levels.

A group of about two dozen researchers and volunteers from all over the Midwest will conduct a mussel survey downstream of the dam.

The DNR says the Iowa River is one of the best places in the state for the mussels.

"When you drop the water, they tend to slowly move," Castle said. "If they're left high and dry in the mud, they'll move down into the water again if they're there when we make the change, they hope to find some as the water recedes."

The group will feel around in the water to find the mussels. Some divers will also take part in the search.

The survey and the construction project are expected to take a little more than a week to complete.

[nggallery id=618]