Indiana Freshwater Fishing
Low-head stream structures have a dark side
Everyone enjoys the peaceful sights and sounds of water cascading over a dam. Anglers congregate downstream of dams because fish concentrate in the deep pool below. Some swimmers and paddlers find excitement in recreating in the turbulent water associated with dams.
While they offer an allure, the low-head dams that span many Indiana streams have a dark side.
The reason anglers flock to them is one of the main reasons low-head dams are bad for the aquatic community … they block fish that normally are highly mobile from reaching upper portions of a stream.
This blocking effect also harms freshwater mussels. The reproductive strategy of mussels relies on fish to move the young. Dams restrict how far the mussels can be distributed. Freshwater mussels are highly endangered and one reason is the presence of dams.
The pool area on the upstream side of a dam creates unnatural habitat for stream fish, causing them to avoid the area. Typically, pooled areas become dominated by undesirable species, so each dam creates an overall reduction in gamefish species.
Low-head dams also create dangerous currents that are notoriously hazardous to individuals who fish, boat or swim near them. While many low-head dams pose less of a recreational risk during low-flow conditions, they become wickedly dangerous during moderate and high flows.
High flows over a low-head dam push victims under the water surface in a recirculating current that pulls them back to the face of the dam. The repeating cycle traps and drowns the victim, which led to the moniker “drowning machines.”
Approximately 10 percent of drownings in Indiana occur at low-head dams. Of those drownings, 75 percent of the victims were recreating; the other 25 percent were attempting a rescue. See vimeo.com/192003847?ref=em-share for more on the hazards of low-head dams.
Many low-head dams no longer serve a purpose and most are in disrepair. The Division of Fish & Wildlife is looking for opportunities to partner in removing obsolete dams so that the aquatic community of streams can be improved and the streams can be made safer for recreational users.