Low-Head Dams

Low-head dams, sometimes called weirs or run-of-the-river dams, are impounding structures built to control water flow, supply water or support historic mills. While the water upstream of the dam may appear tranquil and harmless, these dams create powerful recirculating currents known as a “spin cycle” that can trap even the strongest swimmers wearing a floatation device. Once caught in a spin cycle, it is almost impossible to escape.

Low-head dam in Richmond, VA

Nearly 800 fatalities have been recorded at low-head dams in the U.S., according to the Low Head Dam Fatalities Database.

Virginia is home to 154 low-head dams, according to the National Inventory of Dams Low-Head Dam Inventory. Launched in October 2025 by the U.S. Army Corps of Engineers, the inventory features an interactive map with information on low-head dams in the U.S., including their location, the size of the dam and if there was previously a fatality. The inventory also features educational information about low-head dams.

If you think you spot a low-head dam, it is crucial that you do these 3 things:

Get out of the water.
Carry your boat, canoe or kayak around the dam.
Re-enter the river at a point well downstream.

You can take the following steps to protect yourself:

Know before you go: Check your route, read maps, talk to locals and obey signage.
Watch for a smooth horizon line where the stream meets the sky and look for concrete retaining walls on either side of the water. These could be signs of a low-head dam.  
Never try to dive in to help someone caught in a spin cycle. Exit the river and call 911. Use a rope or throw bag to pull them to safety.

In cooperation with Virginia Department of Wildlife Resources, we urge everyone to stay safe by avoiding low-head dams while enjoying rivers and streams.

Low-head dam safety awareness poster

Find more safety tips at https://dwr.virginia.gov/boating/education/lowhead-dams/