In a story for The Citizen last month, I looked at what it would take to make Philadelphia’s rivers clean enough for swimming. The answer I heard over and over: Stop the sewage overflows.

When it storms, rain water overwhelms our combined sewer system, sending stormwater runoff and waste water from our homes directly into our rivers. Annually, the combined sewage overflows dump an average of 12.7 billion gallons of polluted water into the rivers. Sixty percent of the city has combined sewer systems.

Now, a new report from PennEnvironment quantifies just how dirty these sewage overflows are making our rivers. It looks at state and federal data on E. coli, a bacteria associated with severe gastrointestinal illness, from 653 monitoring locations across the state. Philadelphia’s stretch of the Delaware had potentially dangerous levels of E. coli on at least one day in 2024 or 2025 at 37 out of 43 testing sites. Twelve of those sites had dangerous levels of the bacteria on every single testing day.

“I want to say this plainly: That means poop,” Lucia Osborne, Delaware Bayshore program director for the American Littoral Society, says. “Sewage pollution has real consequences. It makes our rivers unsafe for swimming and paddling. It can cause serious gastrointestinal illness, and it reduces oxygen levels in the water, which harms fish and aquatic life.”

This is not just a concern for those using the river for recreation, either. Anyone whose basement floods in one of our many, many rainstorms this summer would probably like some assurance that they don’t have to worry about sewage in their homes.

Between 2016 and 2024, combined sewer overflows (CSO) dumped an average of 12.7 billion gallons of sewage in the rivers annually. It can be difficult to track whether people actually got sick from swimming, however, because E. coli and other waterborne illnesses tend to go underreported. Researchers estimate 87 million Americans get sick each year from swimming, boating, or fishing in public waters.

PennEnvironment mapped the testing sites so people can see where the river is safe and where it’s struggling. Osborne compared the PennEnvironment map against one from the Delaware River Basin Commission that found humans are the dominant source of bacteria from the Northeast’s Pennypack Creek to New Jersey’s Cooper river. (Though geese poop, agricultural runoff from further up the river and other factors can also contribute to E. coli in the water.)

Philadelphia’s stretch of the Delaware had potentially dangerous levels of E. coli on at least one day in 2024 or 2025 at 37 out of 43 testing sites. Twelve of those sites had dangerous levels of the bacteria on every single testing day.

And how’s our other river, the Schuylkill, faring? PennEnvironment used 2024 data from the National Water Quality Monitoring Council’s Water Quality Portal, and the state gave them its testing data for 2025. It only included data points for the Schuylkill near Philadelphia at its confluence with the Delaware. For those points, the Schuylkill had potentially unsafe levels of E. coli on 55 percent of the days tested. There was no data for the Wissahickon, though it’s a popular recreational site.

Philadelphia has officially banned swimming in its natural waters, though that doesn’t stop people from jumping into Devil’s Pool or wading into the Wiss on a hot day. Plus, swimming isn’t the only form of recreation. On August 12, when PennEnvironment revealed the results of their analysis at the Fairmount Waterworks gazebo, anglers were casting lines into the Schuylkill near an algae bloom. Groups of rowers launched their shells from Boathouse Row. High levels of E. coli put them at risk, too.

“I was at Pennypack Creek two weeks ago and counted over 100 people at various locations swimming,” Osborne says. (That same creek had unsafe levels of E. coli 73 percent of the time … gross.) “People are doing it anyway. They should have access to safe, clean water.”

Further up the river in Bucks County, the Delaware frequently met water quality standards for safe swimming. Its Neshaminy Creek was only unsafe on 26 percent of the days tested. It’s likely cleaner there, in part, because they don’t have combined sewer overflow outlets there.

“There are more people in the city and they should have access to water that is safe for them to touch,” Osborne says.

What can the City do?

Right now, the City uses green infrastructure, like rain gardens and stormwater planters, to soak up rain water, part of the Green City, Clean Waters plan, diverting more than 3 billion gallons of polluted water from the rivers annually. The Manayunk Canal and several other waterways are much cleaner because of these efforts. But the experts don’t think the plan is enough to keep up with Philadelphia’s aging infrastructure paired with the strain of climate change.

New projects cost a lot of money. But other cities have made clean water a priority. Baltimore spent $2 billion upgrading its sewers — with more projects to come. Deep Tunnel, Chicago’s massive, underground polluted stormwater holding tank, cost $1.223 billion when the City built it … in the 70s. Federal cuts to infrastructure funding make it more difficult for cities to pull off these kinds of projects, too.

Osborne says 10 sewage outlets are responsible for 56 percent of sewage overflows in our rivers. Fixing those would go a long way toward reducing pollution in our water. She thinks the City could look at financing options, like century bonds or asking the largest dischargers to pay higher stormwater fees, to help make the costs of projects more manageable.

We could also tackle a few, lower cost projects. New Jersey requires combined sewage outlets to have nets to capture larger pieces of debris before it hits the waterways, says Stephanie Wein, clean water and conservation advocate with PennEnvironment,. She’d love to see something similar here.

“That’s cheaper. That’s easier than some of the bigger, long-term projects,” she says. “There’s not one silver bullet. There’s a lot of pieces we could be working on.”

It might take the City a while to find the money and time to implement these solutions. Until then, local leaders can help residents recreate safely by being more transparent. Wein, who grew up near Second Beach in Middletown, Rhode Island, remembers her local government issuing alerts when sewage overflows left the ocean too polluted for swimming. New York State does something similar, issuing “wet weather” and combined sewer overflow (CSO) advisories when pollution levels might be high due to recent storms. Philadelphia could do the same.

“The citizens of Philadelphia should have access to what the current water quality is, just like coastal residents do, so they can make those decisions for themselves to safely enjoy our waterways,” Wein says.

“If people want to go wade in the Tacony Creek or put a boat out at Bartram’s Garden — which often has to cancel kayaking because of a recent CSO — then they should be able to have that [water quality] information publicly available … We have a right to enjoy our waterways. That’s why our nation came together over 50 years ago to pass the Clean Water Act.”

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