Residents in Derry Borough evacuated over concerns of ‘seepage’ from dam

Westmoreland County emergency officials have issued a precautionary evacuation order for residents near the Lower Ridge Dam in Derry.

“We have some seepage in the dam, we have heavy rain, so we’re issuing an evacuation order to approximately 90 people until the water drops,” said Amy Forsha, manager of the Derry Borough Municipal Authority, which manages the dam.

Ms. Forsha could not give an estimate of when the evacuation warning would expire.

The Lower Ridge Dam impounds water for Ethel Springs Lake.

Derry Borough is about 50 miles east of Pittsburgh.

The evacuation comes just a week after concerns of another dam leak in southwestern Pennsylvania.

On Sept. 3, Somerset County officials and the state’s Fish and Boat Commission warned residents downstream of the High Point Lake dam in Addison Township. The commission later found that interior pipes and valves — rather than the earthen structure — were leaking.

The cause is still under investigation, but the dam is structurally sound, said Michael Park, communications director of the Fish and Boat Commission.

Heavy rain since Saturday has stalled the investigation, which involved lowering the water level of the lake to find the source of the problem.

“While we had made progress, this heavy rain [is] going to replenish the water level,” he said. “So it is slowing the process for us. But this is a long-term event and it’s going to take some time for us to locate the issue and fix the problem.”

Any flooding experienced by residents downstream of High Point Lake is a result “of Mother Nature,” not the dam, Mr. Parker said.