The Brandywine River Restoration Trust recently began removing part of the DuPont Experimental Station Dam in an effort to bring migrating fish further upstream.
The deconstruction of Dam 6, also known as the Lower Hagley Yard Mill Dam, will help allow shad to swim further up the Brandywine as they did 300 years ago before the dams were constructed.
The overall dam removal project is reconnecting 11 miles of river for migrating fish. The 11 dams along the Brandywine were previously used to power mills in the 19th century.
The Brandywine River Restoration Trust executive director Jim Shanahan said dam removal will also reduce flooding and increase the biodiversity of the area.
“It's sort of like if you live in a city and you can only go from 10th Street to 15th Street, and your whole life has to live between those five blocks,” Shanahan said. “When you open up a dam, you basically extend the space for the different wildlife, both flora, fauna, to exist in there.”
He added results will be visible fairly quickly – in a matter of years rather than decades. Within one year, shad traveled further up the river after Dam 1 was removed.
Shanahan said living things on both ends of the food chain are going to see benefits.
“Birds of prey, ospreys and eagles feed on shad,” Shanahan said. “Since we've removed the first dam in Downtown Wilmington, we've actually seen more Ospreys in this area, which is a little bit unusual. On the other side of the food chain, mussels, freshwater mussel larvae get attached to the gills of shad as they migrate up the streams and rivers.”
Larvae are then deposited upriver and grow into mussels, which act as filtration devices for the river.
Removing dams from the Brandywine is also an effort to mitigate flooding.
“There's a significant amount of flooding that occurs adjacent to Dam 6, which is a DuPont facility known as the Experimental Station,” Shanahan said.
While the dam is defunct, it contributes to occasional flooding in the watershed following heavy rains, according to the BRRT.
The project is made possible through funding from multiple sources, including the National Fish and Wildlife Foundation, the State of Delaware and the U.S. Fish and Wildlife Service.
