The Story of a Watershed Park

News // February 14, 2024

by Lisa Stout, FOW Crew Leader

On a few occasions, I’ve taken people who are new to the Wissahickon for a hike, and eventually, the same question has come up. We run into a concrete structure sticking out of the ground with a manhole cover on top of it. My guests ask warily, “Is that a…sewer pipe?” There’s a look as if their cat has dropped a mouse at their door.  

My response to this is to enthusiastically say, “Yes! It’s a sewer pipe! It’s a great reminder of how the Wissahickon was created as and still is a Watershed Park!” I might have to explain what I mean by a watershed, which is all of the land that drains into a particular water body, such as the Wissahickon. Then I tell the story that goes something like this: 

As European settlers moved into the Wissahickon Valley in the 1700s and 1800s, more settlements and mills began popping up around the creek. Downstream in the city of Philadelphia, the population was expanding. People were getting their drinking water from local springs or wells, and discharging their waste into the streets and streams near them, where it would be carried further downstream. This worked out ok until it didn’t…and by 1793, a massive yellow fever outbreak killed about 5,000 people (out of a population of about 50,000). At the time, it was thought that the disease, which had been occurring for years even before this massive outbreak, was the result of the odors from waste in the streets and streams, the “exhalations of the city.” While yellow fever, in particular, was later discovered to be caused by a virus transmitted from person to person via mosquitoes, it served as a motivation to clean up the city and provide clean water to its residents, eventually leading to the construction of the Fairmount Water Works. 

In the meantime, back in the Wissahickon, more mills and more houses were being built, as elsewhere in the city. By the 1830s, flush toilets were being made, but they were flushing into the ground, and eventually, that waste ended up in streams. Diseases such as typhoid fever, a bacterial infection transmitted through contact with human waste, were on the rise, and by the later part of the 1800s, city officials realized something had to be done.  

In the 1860s, the land around Wissahickon Creek was incorporated into Fairmount Park, created by purchasing land along the Schuylkill River and Wissahickon Creek to protect the water supply (hence, a ‘Watershed Park’). City planners started taking steps to hook houses and their flush toilets into the already existing storm sewer pipes to ‘intercept’ this waste before it ran into the streams and rivers that were used for drinking water. By the 1880s, massive ‘interceptor sewers’ were being built along the Wissahickon, which are still in use today. The large sewer pipe that is part of the White Trail and the iconic Cresheim Aqueduct, built in 1892, are examples of these interceptor sewers. 

While sewage from homes ends up in sanitary sewers and makes its way to the city’s Water Pollution Control Plants, stormwater that does not end up in storm sewers can run off from yards and roads into the creek. This stormwater can cause erosion, and it can add sediment and pollutants from yards and roads to the Wissahickon. What can you do if you live around the Wissahickon? If you have a yard, consider planting native plants adapted to this environment that can slow down the runoff of stormwater and filter the water before it enters the creek. Think about what you are adding to your lawn, such as chemical fertilizers. Keep trash out of the creek by participating in litter clean ups to keep trash from entering the creek!  

So, next time you’re in the Wissahickon and you see those sewer pipes, think about how they’re part of a bigger system that was created to protect the waterway, and you might feel a little bit different about them! 

Philadelphia’s Watershed History – Philadelphia Water Department 

Philly H2O: Home Page ( 

Philly H2O ( 

How Philadelphia’s Water Pollution Problems Shaped the City | Science History Institute 

History | 

Photo courtesy of Chuck Uniatowski