A leak in Deep Creek Dam in Garrett County prompted an alert to area residents, Maryland Department of the Environment officials reported.
There was no immediate threat of the dam failing, according to state officials.
"MDE has sent staff from our compliance program to investigate the leak," MDE Secretary Shari T. Wilson said in a statement. "We will continue to monitor the situation as long as necessary to ensure the safety of Maryland residents living in the vicinity."
The leak is in the penstock, which takes water from Deep Creek Lake to the dam's powerhouse. The plant will remain closed until repairs are done and reviewed, said Robert Ballinger, an MDE spokesman.
"This is really just a notification," he said. "There is no fear of damage to the dam itself or of overflow. It is a precaution of our emergency plan to notify people what is going on."