FRANKFORT – Fearing a dam break that could cause catastrophic flooding in Kentucky and Tennessee, the U.S. Army Corps of Engineers began lowering the water level on Lake Cumberland on Monday.

The measure was aimed at reducing pressure on the weakened 240-foot-high dam, said Lt. Col. Steven J. Roemhildt, commander of the Corps of Engineers’ Nashville office.

&#8220We must take this emergency action to reduce risk to the public and to the dam itself,” he said in a statement.

If the dam, which is nearly a mile long, were to break, flooding in communities downstream along the Cumberland River could kill people and cause an estimated $3.4 billion in damage, Roemhildt said. Cities along the Cumberland include Nashville, Tenn.

Corps spokesman Bill Peoples said failure of the dam was not imminent. But he said people should have evacuation plans ready in Nashville and other downstream communities, including Burkesville in Kentucky and Celina, Carthage, Clarksville, Gallatin and Hendersonville in Tennessee.

Steve Jones, director of the Montgomery County Emergency Management Agency in Clarksville, said he is helping to draft evacuation plans for local residents just in case. He said a dam break could have a devastating impact on people, livestock and crops in the heavily agricultural area around Clarksville.

&#8220Any time I get a heads-up on something like that, I plan for the worst and then hope for the best,” Jones said.

In Nashville, officials said they have an emergency plan that would be put into effect if a dam break caused flooding. City officials have reviewed that plan, said Amanda Sluss, a spokeswoman for the city’s Office of Emergency Management.

&#8220We have re-reviewed some of the plan and addressed specific things that may need to be included if there’s a breach in the dam,” Sluss said.

Scott Harris, the city’s acting deputy emergency management director, said the potential impact on Nashville, which includes a metro area of about 1.4 million people, would be minimized once the water level is lowered.

The dam was built near Jamestown in the early 1950s.

Two recent studies raised questions about the dam’s structural integrity, according to Roemhildt.

Roemhildt said water has been seeping under the dam and eroding the limestone on which the concrete rests. He said crews were pumping grout into the ground to counter the erosion.