Animation: Dangers of Low-Head Dams
Animation Transcript
Transcript for Dangers Posed by Low-Head Dams
The low-head dam is the most dangerous type of dam and has been named the “drowning machine.”
They may not be easily spotted because the top of a low-head dam can be several feet below the water’s surface.
Because of their small size and drop, low-head dams do not appear to be dangerous.
However, low-head dams pose a serious danger to vessel operators, both above and below the dams.
Surface currents below low-head dams can suck vessels toward the face of the dam.
Currents above low-head dams can sweep vessels over the dam.
The recirculating currents and turbulent waters below can swamp vessels and drown boaters. Low-head dams vary in height from one to several feet below the water’s surface. Though their drop may be small, you must never assume you can go over without danger. And remember that water going over a low-head dam creates a large recirculating current or backroller (sometimes referred to as the “boil”) at the base of the dam.
Even on small rivers, the force of the backroller can trap your vessel against the face of the dam, and pull you under the water—even while wearing your personal flotation device (life jacket).
Be aware that on large rivers or during high water the backroller or boil may be located more than 100 feet downstream of the dam. Avoid low-head dams.
