Earlier this year, digital equipment at the Black Rock dam in Phoenixville recorded a momentous occurrence: three American shad adults swimming by, presumably headed up the Schuylkill to spawn.
They had made it past five dams - one that had been breached and four with fish ladders installed in recent years.
"It's been almost 200 years since an adult American shad has been that far up," said Philadelphia Water Department biologist Joe Perillo.
The find was a bright spot in what has turned out to be a stubbornly elusive goal in the Delaware River basin - the restoration of American shad.
Some hopeful signs abound, but the once-legendary fish still awaits a comeback.
Their runs had been so amazing that river towns held celebratory festivals. (Lambertville still does.) Community dinners featured the icons of spring - lilacs on the tables, shad in the pans, and roe smothered in butter on platters.
It's the muscular, give-'em-hell shad, lauded as the fightingest freshwater fish of all, that brings anglers to the river come spring, their boats once crowding so thickly that it was said you could walk across the river atop them and never get your feet wet.
It's the shad that may have saved George Washington's troops that brutal winter at Valley Forge. John McPhee titled his book about shad The Founding Fish.
And it was the eventual plight of the shad that led to the formation of the Pennsylvania Fish and Boat Commission in 1866.
Their attempted salvation has not been for lack of effort or money.
A state hatchery operation that costs $250,000 a year has produced millions of young shad that are released into rivers - more than six million into the Schuylkill alone.
Millions of public and private dollars have been spent to alter or remove dams in Southeastern Pennsylvania, giving shad access to their historic spawning grounds.
The pollution that once killed fish trying to spawn upstream through the urban stretches is long gone as well.
But where are the fish?
Shad numbers in the Delaware rose briefly in the 1980s. "Everyone thought of it as one of the big success stories," said Rich Horwitz, a fisheries expert at the Academy of Natural Sciences of Drexel University.
Then, the numbers fell.
Over the last few years, fishery scientists think they're seeing hopeful signs on the Delaware - more shad moving upriver, and more being caught by the recreational and few small commercial fisheries.
"Starting in 2009, all our adult indices and some juvenile indices are making an upturn," said Jerre Mohler, the Delaware River coordinator for the U.S. Fish and Wildlife Service's Northeast Fisheries Office. But it's too early to say if that's a blip or the beginning of a trend, he added.
"Good things are happening," said John Berry, a Bethlehem retiree and one of 600 members of the Delaware River Shad Fishermen's Association. "It's just that, quite honestly, not enough good things are happening."
As a whole, the East Coast population of American shad is considered "depleted."
Scientists working to restore the shad are finding that everything is connected. Among the reams of charts and data sets is one showing that as striped bass numbers have increased, the population of shad shad - their juveniles often prey of striped bass - has fallen. The lines on the chart look like a big X.
In recent years, attention widened to what was happening offshore, where shad spend four to six years growing to maturity.
It turned out that they school with Atlantic mackerel, then wind up snared in the nets of fishing trawlers.
The mackerel fishery is one reason Cape May consistently ranks second on the East Coast for the annual value of seafood landed. In 2010, the last year for which data are available, it was $81 million.
But the bycatch of shad in East Coast offshore waters has been estimated at more than 115,000 pounds a year.
"In some cases, they were catching more . . . shad than would be returning to entire states," said Kristen Cevoli, an associate in the Pew Charitable Trust's Northeast Fisheries Program.
So recently, the Mid-Atlantic Fishery Management Council, which oversees fishing in federal waters, took the unusual step of proposing restrictions on one fishery, the mackerel, to help another, the shad. (In truth, the measure was also to protect river herring, shad cousins that are in even worse shape.)
Officials proposed that ships have observers continually on board to assess the bycatch. And they want a cap on the mackerel catch.
Jeff Kaelin, government relations coordinator for the biggest finfish company in Cape May, Lund's Fisheries Inc., doesn't object to the new regulations. He thinks they are unlikely to have much effect, because the company has already instituted its own plan to reduce the bycatch. And warming ocean temperatures have pushed the mackerel farther north anyway.
Stocking the Schuylkill
A bright spot is the Schuylkill, although that, too, has been a long time coming.
Tiny shad "fry" - grown at a Juniata County hatchery from eggs and sperm gathered from shad netted on the Upper Delaware - have been stocked regularly since 1999, nearly half a million a year.
Four fish ladders and three dam breachings have opened 100 miles of Schuylkill to fish passage, although not always to the shad's liking.
At the circa-1979 fish ladder on the Fairmount Dam - the first one they encounter - an underwater camera caught a cameo appearance by a river otter, which was cause for great celebration because otters are a sign of clean water. But only 100 or so shad were coming through each year.
The dam was rehabbed in 2009 at a cost of $3.3 million, paid by the Philadelphia Water Department and the U.S. Army Corps of Engineers.
Bingo. In 2009, about 1,500 shad came through. The year after that, 2,500. And last year, nearly 3,400 shad moved upstream through it.
Mike Hendricks, a fisheries biologist with the Pennsylvania Fish and Boat Commission, said "success" on the Schuylkill would be at least 250,000 shad going through the fish ladder at Fairmount. "That's a lot," he acknowledged. "I don't know if we'll ever get there. If we have just a self-sustaining population, that would be great."
Elsewhere in the Delaware River system, dam removals continue, including four total on the Brandywine and Darby Creeks. So many dams have been taken out in Pennsylvania - the state is interested because many present a drowning hazard - that the advocacy organization American Rivers has declared the state a national leader.
In July, workers in New Jersey began removing a Raritan River dam, using pollution settlement money.
The Lehigh River has two innovative programs that Berry thinks hold promise for other tributaries.
One is a voluntary shad co-op, where spawning shad are corralled into tanks. There, they produce more eggs than the hatchery can. And they provide an educational moment. People coming off a nearby canal boat can look at a video feed from the tank. "They are awe-stricken with the size of the fish and how fast they swim around that tank," Berry said. "It's been a real success."
Scientists involved in the Schuylkill efforts would like to see a similar co-op as part of the Interpretive Center at the Fairmount Dam.
Berry of the shad association thinks the Delaware still has world-class shad-fishery potential.
The tourist economy would benefit, sure, but more than that: "Picture, if you will, if you had two million fish coming back every year to spawn, and each was four pounds. It would eclipse all trout fishing. It would feed all the wildlife - otters, mink, raccoons, crawfish, bald eagles, ospreys, herons, kingfishers," Berry said. "My goodness, you'd have a tremendous contribution to the ecosystem."