A confluence of public safety, recreation and natural heritage concerns is powering an impetus to remove low-head dams across Indiana.
The state has more than 140 low-head dams. Most often made of concrete, they were built on Indiana’s rivers and streams to serve a variety of purposes, such as raising the water level upstream for ease of boat navigation, creating shallow waterfalls for the generation of hydro power, and pooling of water for supply or irrigation intake.
Many Hoosier low-head dams no longer serve a purpose but have been left in place because they’re costly to remove. A University of Rhode Island study published in 2017 reported that it costs from $381,000 to $456,000 to remove an average-sized dam of 8 feet in height and 100 feet in length.
Ecological benefits of removing the dams include reestablishing natural flow, improved water quality, natural release and transport of sediment and connectivity of species living in the water, according to Indiana Department of Natural Resources fisheries biologist Matt Linn.
Once a dam is removed, flow and water temperature quickly return to their natural state.
“The stream or river typically just reverts back to where it wants to go almost immediately,” Linn said.
EVEN FLOW
Stagnant water can stratify, meaning that warmer water collects at the surface above a cooler layer. But flowing water stays a consistent temperature, which improves water quality.
Flowing water also carries more dissolved oxygen.
Conversely, stagnant water releases more sediment that can accumulate in front of the dam, changing the habitat. Removing the dam can reverse the sedimentation and improve the stream bed.
Dams also limit the movement of animals during spawning, leading to genetically isolated populations.
“Native species adapt back to that system the way it should naturally be very quickly,” Linn said.
According to a map maintained by American Rivers, 11 dams have been removed in Indiana, 10 of those since 2012 and four just last year.
Two of those were in the town of Corydon on Big Indian Creek.
“The dams were built as a water supply for the town in the ‘50s,” said Cassie Hauswald, a freshwater ecologist with The Nature Conservancy. “The use was obsolete, because now the town gets their water from wells and the aquifer of the Ohio River.”
The Nature Conservancy approached the town about removing the dams, and after determining that doing so would not lead to flooding, the town agreed.
The project was funded by the U.S. Fish and Wildlife Service’s National Fish Passage Program, DNR’s Lake and River Enhancement Program and The Nature Conservancy.
ENDANGERED SPECIES
Restoring waterways can help restore species endangered in the state of Indiana.
“It’s hard to say how much of an impact dams are having on a specific endangered species, but certainly restoring streams back to their natural habitat by removing those will not hurt,” Linn said.
For example, freshwater mussels are a parasite that depend on fish to reproduce.
“Some mussels have many fish they can use and other mussels have one species,” Hauswald explained.
Dams obstructing the movement of fish can keep them from encountering mussels.
The city of Muncie also removed two dams last year, The Indiana Steel and Wire Co. Dam and the George R. Dale Dam in McCulloch Park.
Avid fisherman Stephan Jones was fishing the stretch of river between the two former dams recently.
“It has really added to the fishable water,” said Jones, who considers the White River “one of the best smallmouth bass habitats there is.”
TRANQUIL DANGER
As people recreate more on rivers and streams, removing low-head dams can improve public safety.
“Low-head dams can look calm and tranquil, but the reality is if you get too close or become stuck in that hydraulic of that dam it potentially can be a fatal incident,” DNR Conservation Officer Capt. Jet Quillen said.
DNR’s website includes a map of low-head dams to check before getting on the water, enabling water enthusiasts to plan portages around the dams.
“You can be going downstream and not know one is there, and that’s when a lot of accidents do happen,” Quillen noted.
The most recent fatalities at low-head dams in Indiana were in 2017 when three people died in three separate incidents on the Eel River in Whitley County, Big Walnut Creek in Putnam County and the White River in Marion County.
Hauswald is optimistic that the movement to remove low-head dams in the state is picking up steam.
“We have a great diversity of freshwater fish and mussels, and we can improve the habitat for all those things and improve recreation opportunities for Hoosiers,” she said. “Lots of miles of habitat reconnected is definitely why I’m in this game.”