LEONARDTOWN — St. Mary’s County’s Department of Emergency Services is advising residents of additional testing of the Calvert Cliffs Nuclear Power Plant emergency warning sirens from Wednesday, June 3, through Friday, June 5, at various intervals throughout each day.
The extended testing follows the previously scheduled semi-annual full-volume test set for Monday, June 1, at noon. Officials said the additional tests are needed to verify the intended sound output of individual sirens across the system.
Residents in St. Mary’s, Calvert and Dorchester counties may hear the sirens during the testing periods. In St. Mary’s County, the additional testing will specifically involve two sirens located near the MD 235 and MD 245 intersection and near Shady Mile Drive in California.
The warning system consists of sirens placed within the 10-mile emergency planning zone surrounding the Calvert Cliffs Clean Energy Center in Lusby. The sirens are tested regularly as part of normal maintenance to ensure they operate properly and to increase public awareness of the alert and notification system.
This is one of two semi-annual full-volume tests conducted each year, typically on the first Monday in June and December. The June 1 test will include a three-minute activation of all sirens in the 10-mile radius. The June 3-5 tests will be shorter and targeted at individual units.
The sirens are not a signal to evacuate. In an actual emergency, they would sound a steady tone for three to five minutes to alert the public to tune to a local Emergency Alert System radio or television station for official instructions from county emergency management.
If sirens sound outside scheduled tests and no message is heard on radio or television within about 30 minutes, residents should report a possible malfunction to their county emergency management office: St. Mary’s County at 301-475-8016, Calvert County at 410-535-3491 or Dorchester County at 410-228-2222.
Constellation Energy operates the Calvert Cliffs Clean Energy Center, which includes two nuclear reactors capable of producing enough carbon-free electricity to power the equivalent of more than 1.3 million homes. The plant remains fully operational.
County officials encourage residents to share the testing schedule with family, friends and neighbors. Knowing what to do before, during and after an emergency remains a key part of preparedness.
St. Mary’s County residents can learn more about emergency planning and download preparedness resources at www.stmaryscountymd.gov/em. Similar information is available on Calvert County’s alert notification page.
The siren system is part of the broader Emergency Alert System required by federal regulations for nuclear facilities. Monthly short tests, lasting less than one minute, are also conducted throughout the year.
No public action is required during the scheduled tests. The announcements from St. Mary’s County and Constellation aim to reduce unnecessary concern while reinforcing the system’s role in community safety.
