LOWHEAD DAMS

Low-head dams (manmade concrete structures or natural rock structures) that can be only a few feet wide to as large as the entire width of a river. They should be avoided in most cases. With strong current flowing over lowhead dams, they are potential drowning machines. Once caught in the downstream-side hydraulic, it is nearly impossible to get out even if wearing a life jacket..

The best way to maneuver around lowhead dams when using a canoe or kayak is to portage. Portage means to remove your craft from the water well away from the dam, and carry it around the dam to a new launching point.

• The downstream side of a dam is the most dangerous as this is where the hydraulic is created.
• Boats trapped against the downstream side quickly fill with water and capsize, throwing occupants into the dangerous waters.
• When caught in the hydraulics of a low-head dam, you are carried to the face of the dam, where the water pouring over it will wash down under to a point downstream called the boil.
• The boil is a position where the water below surfaces and moves either downstream or back toward the dam. A person caught in a boil dam may surface, only to be caught in the backwash again and carried to the face of the dam, continuing the cycle. Even with a life jacket on, the hydraulic may continue to pull a person under. The tremendous force of the hydraulic may pull off a poor fitting life jacket from a struggling person.
• Dams do not need to have a deep drop to create a dangerous backwash.
• During periods of high water, the backwash current problems get worse, and the length of the backwash current is extended downstream.

Although low-head dams do not always look dangerous, they can create a life-threatening situation. You should always know the local area, follow warning signs, markers or buoys, and keep well clear of low-head dams.