[This story was originally published by Delaware Public Media.]
A series of dams along the Brandywine that date back some 200 years are targeted for removal or modification starting this year.
It’s part of an effort to allow shad, eels and other fish to return to their ancestral spawning grounds again for the first time in two centuries.
Contributor Jon Hurdle reports in this effort and its potential impact.
Alongside the historic Hagley Museum property in northern Delaware, the Brandywine Creek tumbles over four dams which once generated the water power that drove the creek’s many grist mills some two centuries ago.
The dams played an important role in the state’s economy and industry starting in the early 19th century, but they also prevented the upstream passage of migratory fish such as the American shad to their spawning grounds in the Pennsylvania section of the creek to the north.
Now, the Hagley dams, and six others that survive along the scenic creek are targeted for removal or modification to allow shad, eels and other fish to reach their ancestral spawning grounds for the first time in some 200 years.
Brandywine Shad 2020, a nonprofit led by the Brandywine Conservancy, the Hagley Museum & Library, and the University of Delaware, is hoping after three years of preparation to begin removing dams this year, or to modify them in ways that allow the fish to swim upstream through about 23 miles of the creek.
The program, the largest on the East Coast, and one of the biggest of its kind in the country, aims to replicate and build on the success of smaller dam-removal projects such as one in White Clay Creek, and on the Musconetcong River in New Jersey, both of which have shown that fish quickly return to their upstream spawning grounds as soon as the physical barriers are removed.
“The project target is to remove or modify the remaining 10 dams, enabling the fish to swim free to their historic spawning grounds in Pennsylvania,” said Hunter Lott III, co-founder of the group, at a recent meeting of officials from UD, Hagley and Kleinschmidt, an engineering firm that is designing the dam work.
Removal or modification of all 10 dams, plus one at Wilmington that was demolished last fall, has the potential to produce more than 26,000 additional shad, according to a UD study in 2015.
Removing the dams will not only lure fish back into the creek, but will improve water quality by improving dissolved oxygen; lower water temperatures, attract birds and other wildlife, improve opportunities for anglers and boaters, and restore an ancient natural rhythm that hasn’t been seen in the Brandywine since the early years of the republic, the advocates say.
But they face challenges including the demands of different dam owners, the need to preserve some dams because of their historic value – and the consequent need for federal permits — and the demand for funding.
Dr. Jerry Kauffman, director of UD’s Water Resources Center, said he believes it’s “feasible” to remove four of the dams this year but acknowledged that the funding is not yet in place to do so.
Brandywine Shad 2020 received $241,000 from the National Fish & Wildlife Foundation as a result of the Delaware River Basin Conservation Act, a law that began providing federal funding for conservation projects in the watershed starting in fiscal 2018. That sum was matched by the State of Delaware – which owns three of the dams – but more is needed.
Three dams on the Hagley property cannot be removed because they are National Historic Landmarks, and help Hagley tell its story to visitors.
Dam No. 2, at Brandywine Park and Broom Street in Wilmington must also be preserved because it is part of the city’s drinking water intake from the creek, Lott said. Therefore, fish passage must be engineered in a project that’s estimated to cost $1.4 million, Lott said.
Dam No. 1, at West Street in Wilmington, was removed by the City in the fall of 2019, and is seen a good start to the overall project, officials said.
Kauffman of UD predicted that the return of shad to the Brandywine will create excitement among anglers in Wilmington. “It’s going to wake up downtown Wilmington in the spring because there are some big shad in the Brandywine that were never able to move past Market Street,” he said.
Because they must be preserved, the Hagley dams will have to be modified to allow fish to pass on their way upstream. Techniques for doing so include building a gradual slope called a “rock ramp” across the full width of the creek on the downstream side of a dam, allowing the fish to crest the dam and continue on the other side.
Contractors could also build a 10-foot-wide concrete channel known as a fish ladder, although that is not as effective as a rock ramp, said Todd Kreider, an ecological engineer with Kleinschmidt, at the Hagley meeting. Or they can create a “bypass” that allows the fish to swim around the side of the dam.
Despite an array of technical, financial, and regulatory challenges, the program has the ability to overcome them this year, Lott predicted.
“We’ve got competent people who know the ropes here and I think that by mid-summer we will have everything set up so that if we do raise some money we can get some equipment in the river and start,” he told the meeting.
Advocates are hoping to obtain more federal money from a new round of funding via NFWF, and are targeting about half a dozen other sources, officials said.
Dam removal is a proven technique for restoring fish migration, as shown by UD’s White Clay Creek project in 2014, which demolished the remains of one Revolutionary War-era dam, and has resulted in shad now moving 4-5 miles upstream toward Newark, albeit in small numbers, Kauffman said.
In northwestern New Jersey, the Musconetcong River Watershed Association has led the removal of five dams since 2008, at a total cost of about $2 million, and has been rewarded with the immediate return of shad and other migratory fish to some six miles of the waterway above its mouth where it joins the Delaware River.
“They came back immediately,” said Alan Hunt, executive director of the association. “Some people used to think this was a like a generational outcome, that the fish were going to have to relearn how to go back,” but the results were a lot quicker.
Hunt attributed his group’s success to the building of a partnership between dam owners, engineers, and the regulators that oversee the structures. The group meets three times a year to discuss priorities and identify possible sources of funding, he said.
In Delaware, dam-removal advocates can point to a range of environmental, historical or educational justifications for bringing back the fish migration, but fundamentally, it’s about restoring a natural balance, said Jim Shanahan, co-founder of Brandywide Shad 2020.
“To me, it’s very simple,” he said. “It’s about restoring one of the most beautiful and historic rivers in the United States to its natural state. I like to think of it as God’s work.”