Downsides of Dam Removal

States have been removing old dams from rivers for safety and environmental reasons. But researchers say water managers should be sure to take a close look when considering dam removal as an option because, in some cases, it might be bad for the environment. The Great Lakes Radio Consortium’s Mark Brush has more:

Transcript

States have been removing old dams from rivers for safety and
environmental reasons. But researchers say water managers should be
sure to take a close look when considering dam removal as an option
because, in some cases, it might be bad for the environment. The Great
Lakes Radio Consortium’s Mark Brush has more:


This year, 45 dams are slated for removal across the country. Half of
those dams are in this region.


Emily Stanley is a river ecologist at the University of Wisconsin.
She’s been studying rivers after a dam has been removed and recently
published her findings in the journal “BioScience.” She
says in farm country, dams can help trap fertilizers that have been
over-applied on nearby fields.


“Small reservoirs can act like wetlands, and can be effective filters
for removing the nitrogen that has come in off of farm fields through
groundwater into the system, and can be actually some valuable points
of improving water quality.”


Stanley says, in many cases, sediments have been collecting behind the
dams for decades. When the dam is removed, the sediments are suddenly
released downstream and can lead to harmful algae blooms. In some
cases, the sediments can contain more dangerous substances, such heavy
metals and PCB’s. Stanley says communities should be sure to weigh the
environmental consequences before removing a dam.


For the Great Lakes Radio Consortium, I’m Mark Brush.