Occoquan Dam Siren Testing on Nov. 18

A test of the Occoquan River Dam siren will be held on Tuesday, November 18, 2025, at 10:00 am.

To further ensure the safety of the residents, visitors and businesses along the Occoquan River shoreline, Fairfax Water installed sirens to warn people in the highly unlikely event that there is ever a massive failure of the Occoquan River Dam.

Who's impacted?

The impact zone includes areas in Prince William County & Fairfax County located immediately adjacent to the Occoquan River from the Town of Occoquan to Belmont Bay. This includes the town, marinas, Occoquan Regional Park, and other residences and businesses adjacent to the river.

 

What does the siren sound like?

The siren is a loud whooping noise. You can hear what it sounds like by clicking here.

How do I know if I'm in the impact zone?

Just because you hear the siren does not mean you are in the impact zone. Find out whether or not you are in the impact zone or the noise zone by typing in your address in the search bar below. If you are located within the red boundary then you are within the impact zone.

What should I do?

During the siren test, there is no need to seek higher ground. Any other time, if you hear the siren and are in the impact zone, seek higher ground immediately! If you are not in the impact zone, no action is

necessary.

Learn more at fairfaxwater.org!