Fremont Rescue
Low-Head Dams
Low Head Dams - The Drowning Machine
Low Head Dams may look peaceful but most recreationalists are not aware of the serious risks associated with low-head dams.
An obvious danger is encountered when a boat is carried downstream over a dam, yet the most serious danger occurs immediately below the dam, where hydraulic effects can submerge a person or a vessel and keep it submerged within a few feet of the dam. Also, the person can become entangled in underwater debris, and not be able to free themselves.
Boats that approach a dam too closely from downstream may actually be carried toward the dam by the reverse current. Once caught in the rotating current below the dam, it is very difficult to escape.
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A cautionary statement to anyone floating Idaho rivers and streams:
Know the river area you are going to float BEFORE you float! Fremont County alone has thirteen hazardous low-head dams, five on the Snake River, four on Fall River, and four on Teton River. These low-head dams are unforgiving and dangerous, and under no conditions should individuals attempt to go over them during any time of the year. Water recreationists must learn all the dangers of the streams, rivers, and low-head dams. Anyone who uses these water sources should determine beforehand where these dams are and avoid them.
An additional note to individuals attempting dam sliding: This is also very dangerous and should be avoided. Parents, please caution your children of these dangers.
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Unseen DANGER lurks above & below
all Low-head Dams
Beware ! ! !
Unlike rapids, the moving water below the dam flows back upstream trapping and carrying objects back toward the dam. Boat motors or paddling efforts are powerless against the river due to the amount of air being created in the churning water.
Why the Danger?
Dams are difficult to spot from upstream and often are not marked by signs or buoys
Dam hydraulics are unpredictable
Dams can deceive even experienced boaters
Areas immediately downstream also present risk as the water is flowing upstream
Rescuing trapped individuals is dangerous and often unsuccessful
Safety Tips:
* Scout the river and know the location of hazards
* Boat with experienced, responsible boaters and learn from them
* Watch for a smooth horizon line where the stream meets the sky
* Look for concrete retaining walls which are part of the dam structure and easier to spot
* Portage around all dams
* When portaging, re-enter the river at a point well downstream of the backwash
