Low-head dams are deadly traps of moving water. Most were constructed before people thought about using the waters for boating and other forms of recreation. Usually the dividing line that you either continue downstream or are pulled back to the dam by the "hydraulic" is the "boil." The "boil" is the area where the water continues to resurface from the "hydraulic" and isn't flowing upstream or downstream. A person caught in the recirculating "hydraulic" portion of the dam's waters becomes a drowning victim. To see how all this happens and the power of moving water, click on the button below or go back to one of the videos.