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The Brandywine Conservancy wants the dam under Route 1 removed.
The Brandywine Conservancy is working to take down the Hoffman Mill dam on Brandywine Creek on Route 1. According to the conservancy’s Community Services Director Grant DeCosta, removing the dam is a matter of safety, flood reduction, and sustainability of the health of the stream itself.
DeCosta said the dam adds to the flooding issues because it creates what he calls “an impoundment behind it,” meaning water sits behind that area and doesn’t flow during heavy rains. . “Having an abnormal backup in the back [the dam] creates higher groundwater levels in the surrounding plains.” And that, he said, reduces the floodplain’s storage capacity to absorb excess water during heavy rains. “The floodplain can’t function as well if the dam isn’t there.”
This is called “the drowning zone.” Boaters can get caught in the reverse current in front of the dam if they fall overboard.
Working with DeCosta on the project is Rob Daniels, manager of community services. He likens the floodplain to a sponge and says the backup prevents the sponge from drying out, which causes flooding.
“When the dam is there,” Daniels said, “the sponge is artificially filled with water. When the floodwater comes down, it can’t fill the sponge because the sponge is full.”
The dam not only increases the amount of flooding, DeCosta said, but it can also increase the occurrence of flooding because the sponge is already at capacity.
The dam also creates a safety issue for people canoeing or kayaking down the Brandywine. There is an opening on the west side of the creek next to a culvert that runs under the railroad tracks. And there is a short drop in that breach area. While boaters are told not to go through that area, some do for the thrill of paddling through that part where the water runs faster and deeper. Daniels calls it “an attractive nuisance.”
But it can be dangerous. Boaters can fall from their boats and fall into the backwash of a recirculating current that they cannot escape. Some people have drowned in the Brandywine because they were caught in areas of those currents.
Another reason for wanting to remove the dam is ecological concerns. Removing the dam will improve the creek’s health, DeCosta said. Doing so will restore free-flowing sections and reduce sediment build-up behind the dam. Dams also increase water temperature which has a negative effect on some types of plants and aquatic life.
Daniels added that removing the dam will increase the number of ripples and pools that create a habitat for native mussels and other creatures that filter pollutants from the water. “You multiply the places for useful habitation.”
The idea for removing the dam came about when the conservancy was conducting a water trail feasibility study in 2019. That study focused on improving safety and providing a wider path for the water trail. Daniels said they realized the portage around the dam could be a problem because it’s a long hike under Route 1. Removing the dam improves the recreational aspect of the creek, he said.
The conservancy estimated the cost of the project at slightly more than $300,000, most of which has been secured. But that number is from a 2019 estimate, so it may need to be recalculated.
To date, nearly $268,00 has been raised from the National Fish and Wildlife Foundation, the Pennsylvania Department of Conservation and Natural resources, and the William Penn Foundation. Pennsbury Township pledged to pay $18,000 and Chadds Ford Township supervisors indicated last month that the township would consider doing so as part of the 2023 budget.
No timeline has been set for the project, but DeCosta said it should only take a few weeks once work begins.
Hoffman’s Mill was built in 1864 and DeCosta said the dam was likely built at the same time because its purpose was to channel water into the creek to power the mill. The mill ceased operations in 1941 and later became the Brandywine River Museum of Art.
About Rich Schwartzman
Rich Schwartzman has been reporting on events in the greater Chadds Ford area since September 2001 when he became the founding editor of The Chadds Ford Post. In April 2009 he became managing editor of ChaddsFordLive. He is also an award-winning photographer.
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