Small Dams Among Most Dangerous

A recent drowning at Great Crossings Dam on North Elkhorn Creek in Scott County underscores the dangers of smaller dams with water flowing over them – what are known as low-head dams. The flow over these dams creates dangerous currents that can trap swimmers underwater or sink a boat.

Low-head dams make an artificial waterfall in the stream. They look innocuous and the beauty of water flowing over them draws people. Old postcards featured low-head dams and the great central Kentucky artist, Paul Sawyier, painted images of the ones on the Elkhorn Creek system. The fishing below low-head dams is usually productive as well.

“Low-head dams draw people like moths to light,” said Sgt. John Anderson, boating education coordinator for the Kentucky Department of Fish and Wildlife Resources’ law enforcement division. “It is so easy to be misled by their calm appearance. From the upper side, they look so innocent and non-threatening. There is no current, they are pretty, calm and seem safe.”

However, they may be the single most dangerous place on any water body. They are often referred to as “drowning machines.”

“There are over 13,000 miles of streams in Kentucky,” Anderson explained, “with lots of low-head dams. They are leftovers from the past and serve no purpose in most cases. Low-head dams are not built as commonly now.”

Their semblance of innocence is what makes them so dangerous. “A drop of a few feet creates a heavy downward thrust just below the dam,” Anderson explained. “It creates a hydraulic that holds a person underwater. You have tremendous downward pressure on your body. You may be a strong swimmer and able to lift several hundred pounds, but the human body is not designed for that situation.”

A hundred gallons of water striking the body creates 835 pounds of force. “The more water, the more force,” Anderson said. “Even with a life jacket on, if you fall below a low-head dam, you will be dragged down and held down. If you get extremely lucky, the life jacket may help you pop out of the current.”

If you ever study a low-head dam, you’ll notice that logs, basketballs, pop bottles or other junk gets hung below them. The debris spins and goes under, but doesn’t float downstream. That can happen to you if you fall below or accidentally go over a low-head dam.

Canoeists, kayakers and others must know if any low-head dams exist on the section they plan to float. Your eyes can fail to detect a low-head dam as you float towards it. “If you are close enough to cast to the dam from the upstream side, the current probably already has you,” Anderson said.

If you hear the roar of water as you near the end of a slack water pool, get over to the bank immediately. Look for a smooth line against the horizon that signals a low-head dam. Also, look for any concrete, stone or brick abutments along both sides of the bank.

Carry your boat around a low-head dam and launch it well downstream to avoid the reverse current caused by water falling over the dam. The reverse current is difficult to see on the surface, but you’ll detect it quickly if your boat is stuck in it. It is scary. You can paddle as hard as you want, yet it is all for naught as your boat creeps closer and closer to the dam face.

“That hydraulic that pulls you toward the dam is a machine that doesn’t stop,” Anderson said.

Wading anglers should realize another danger of low-head dams. “In high water situations, the tremendous force scours a deep hole beneath the dam,” Anderson said. “You can be several feet away from the dam in low water and go from knee deep water to over your head with one step.”

Be careful around low-head dams. Don’t let anyone try to walk or float over one and don’t wade near them. They may be pretty, but are incredibly dangerous.