By first fish, he means the first to clear the new fish ladder downstream of the Norristown Dam, west of the DeKalb Street Bridge.

Soon after Campbell filled the stepped passage with river water in January, the pale pioneer swam through. If all goes as planned, others, such as shad, will follow.

"As soon as we opened up the passageway, we saw this white sucker," Campbell said, identifying the native river dweller by its name. "It's a good sign that the fish ladder will work for migratory fish, too."

Campbell, an engineer hired by Exelon Generation, is seeing to it that one fish ladder is built by spring on the Schuylkill at Norristown Dam, and another by next spring at Black Rock Dam in Phoenixville.

The ladders are aimed at wooing back the American shad, a fish that hasn't been seen in the river since 1820, when the Fairmount Dam was built. Before then, the shad, which winter in the ocean, swam upstream each spring to spawn.

The state Fish and Boat Commission has a plan to restore the shad to its native habitat along the riverway.

So far, according to a state summary, Fairmount Dam has a ladder, but fish have trouble finding it. An upgrade is planned.

In Gladwyne, construction was completed in 2005 on a fishway at Flat Rock Dam.

Three smaller dams at various points in the river will be breached or removed, the summary said.

To help fish migrate, Exelon must provide them a way around the dams and must make the passages inviting. "It's the whooshing sound that's the attraction," Campbell, 58, said.

At Norristown, the river has been diverted for 25 feet by what looks like a concrete and metal bunker.

Inside, the fish ascend a series of wooden steps over which water flows toward them at the rate of six feet per second. It's fast enough to offer resistance but not overpower them.

There's a platform inside where the finny creatures can rest, Campbell said. As they clear the last rung and head into the river, a digital camera records their passage through a glass window.

When the Norristown project is dedicated sometime in May, the public will be able to see the fish swim by, but only via the Internet. What happens underwater remains hidden to visitors, although biologists likely will use the camera to collate the kinds of fish that pass.

Campbell views the project with scientific detachment, but others are fascinated.

"Cool," Jackie Amarose of King of Prussia said when told of the Norristown project. She and friends, out jogging, stopped to check whether fish were visible.

The Norristown Dam was built in 1828. It was owned by the Philadelphia Electric Co., and upgraded over the years by Exelon, the firm that absorbed Peco.

The fish ladder was designed in 2004. Construction began in February 2007. The dam has been deeded to Montgomery County, which will be responsible for its maintenance. Exelon is footing the $4 million bill per fish ladder, Campbell said.

Exelon has shouldered the cost of the fish ladders at Norristown and Phoenixville for different reasons.

In Norristown, Exelon is making good on a legal agreement that its predecessor, Peco, signed in the 1990s. When Peco donated the Norristown Dam to Montgomery County, it promised to build a fishway there if the state ever required one. When Exelon absorbed Peco, the company inherited that obligation, Campbell said.

In Phoenixville, Exelon, as owner of the Black Rock Dam, was subject to the state requirement that all dam owners on the Schuylkill provide a fish ladder.

The Black Rock Dam was also built in the early 1800s. The site, owned by Chester County, contains the remains of a canal lock, part of an old waterway for barges. The barges carried coal from upstate Pennsylvania to markets in Philadelphia.

Exelon has an easement to work at the site and will maintain it over time.

As work proceeds, a historian will be called in to document any significant findings. "These old stone [canal lock] walls have to be preserved, so that will be a challenge at this site," Campbell said.

The fishway will be shorter than the one in Norristown and jut out into the river slightly. When done, the site will be planted with 100 trees.

"I can't wait," said Paul Martino, project manager for Commerce Construction Corp., of Bridgeport, N.J., which is contracted to build at both sites. "It's not every day you get to build a fish ladder."