It's been 200 years since we began taming the Schuylkill, building 32 dams that made the shallow, rocky waterway passable for coal barges and that powered the mill towns springing up along the water's edge.

It's a mostly forgotten anniversary: Little remains of the system beyond a few miles of canals, four dams, and various crumbling ruins.

But one person marking this bicentenary is Sandy Sorlien, a photographer and urban-planning enthusiast on a quest to photograph all 32 dam sites before they're lost to history. An exhibition, "Falling Waters," of 17 of her photos, is on view at the Fairmount Water Works through Dec. 30.

It comes at the same time - exactly two centuries after it was first built - that one stretch of that 108-mile system is set for a renaissance. This entails the renovation of the Flat Rock Dam in Roxborough, preservation of a historic lock building, and restoration of water flow from that site into the Manayunk Canal, making the canal cleaner, deeper, faster, and, for the first time in decades, suitable for boating.

The Philadelphia Water Department aims to finalize designs for the project, an estimated $14 million to $16 million undertaking, by December. In a best-case scenario, it will bid out the work next summer or fall. (Worst case: It's a few years out.)

For Kay Sykora, who has been working for decades with the Manayunk Development Corp. to restore trails and waterfront access there, it will fulfill a long-held dream.

A view of the new dam intake unit above the Manayunk Canal in Roxborough. The brick structure in the middle distance is the old Lock 68. (Philadelphia Water Department)

The inlet to the Manayunk Canal was closed decades ago, leaving an algae-clogged bog fed by storm-water runoff. A fish kill 15 years ago galvanized neighborhood activists on the issue, she said.

"This canal system was pretty amazing in its heyday. It was one of the first. But there's not much left of it anymore," she said.

Yet, with its locks, canal, and dam, this stretch is the only complete section remaining of the Schuylkill Navigation system.

It was also the first section built, fueling the growth of Manayunk, a mill town, in the 1820s.

A view of Flat Rock Dam and Lock 68 from the 1890s.

Sorlien, who works part-time as a watershed educator and artist-in-residence at the Fairmount Water Works, often takes tour groups to the dam. When it's not too muddy, she walks visitors across the dry canal bed, and up into the graffiti-covered brick ruins of the old lock structure.

Recently, she stood amid the rusting gears, pointing out how it used to function and could again.

Lock 68 sluice house ruin at Flat Rock Dam. (Sandy Sorlien)

The navigation system carried coal and goods manufactured up and down river for nearly a century before the last boat went through the locks in 1917.

It supported the growth of the region but nearly killed the river. By the turn of the last century, the Schuylkill was the country's dirtiest, choked with silt, coal dust, and debris. So, in 1947, the state undertook a massive cleanup, dismantling dams to restore water flow.

Sorlien, 62, of Roxborough, lives less than two miles from this site. But like many others, she wasn't aware of its history.

Once she learned about it, while working at the Water Works, she had to photograph it.

She's been making images of the built environment for decades. In 2002, she published a book, Fifty Houses. "It was kind of an elegy to disappearing regional character in architecture and a protest against sprawl," she said. And for the last 15 years, she's been photographing American main streets, often in states of abandonment, for a series called "The Heart of Town."

Along the way, she became a planner herself. She helped develop the SmartCode, a model zoning code designed on urbanist principles, and consulted on planning around the country. Her latest project is the Neighborhood Conservation Kit, a template for residents to design protective zoning overlays. She helped write two for Roxborough, to preserve walkability there.

In the dam system, she recognized the same sense of abandonment she'd seen on those disinvested main streets.

"I was wondering whether anyone had photographed the remains of the system in its entirety in a contemporary way," she said. "These sites are so important to the Schuylkill Valley and to navigation systems in general. To allow them to just disappear is sad."

She began dam-hunting in 2013, and has so far photographed half of the sites, from water and from land.

Sometimes, trespassing is required. At others, the infrastructure was nearly eradicated, so Sorlien had to rely on local guides.

Recently, she found a New York Times article promising: "The artist in search of 'picturesque decay' will . . . [find it along] the Schuylkill Canal." It was dated 1897.

Today, that decay is even more advanced. Sorlien has documented it in all seasons, returning to see the ruins in the snow, and in the summer when they're engulfed in foliage.

"A lot of it is about loss: what we missed seeing and knowing about, the historic preservation issues," she said. "It's a sorrowful thing to see some of these sites. If they could be restored in some way, it would be a wonderful thing."

Now, to Sorlien's surprise, that restoration is in sight, at least on the Manayunk-Roxborough stretch of this system.

Lance Butler, administrative scientist at the Philadelphia Water Department's office of watersheds, said the design, which involves a new dam and channel into the canal, will make the water in the canal about 10 inches deeper and accelerate water flow.

"This project is killing five birds with one stone," he said. It will address structural integrity issues with the dam, improve water quality (and protect the city drinking water supply), beautify the canal, create potential for recreational boating in the canal, and enable historic preservation of the original lock infrastructure.

Sykora hopes it will do even more than that.

It could accelerate other canal-front projects she's working on: opening up the boardwalk there to public use, and clearing out the overgrown locks at the lower end of the canal to make them visible and accessible to tourists. She'd like to add historic markers as well, to remind Philadelphians of how this canal was once vital to the growth of the city.

"The story of the river," she said, "is the story of the history of this whole valley."

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