Low-Head Dams
Because of its small size and drop, a low-head dam does not appear dangerous. In fact, it is the most dangerous type of dam. It is called the “drowning machine.”
Water going over the dam creates a strong circular current, called the backroller or the boil, at the base of the dam. The backroller can trap your boat or board and pull you under the water. Avoid low-head dams, and always carry your paddlecraft around them.
Low-head dams pose a serious danger to vessel operators. 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 these dams can swamp vessels and drown boaters.