This sounds like the same problem with the Lackawanna River and the Scranton area sewage system. That is not counting the coal mining legacy Bore Hole in Old Forge.
"Harrisburg’s sewer system is largely combined, meaning both sanitary sewage — the stuff that’s flushed down toilets and washed down sinks and bathtubs — and stormwater pass through the same pipes and treatment facility. The system can handle only so much water and waste, so during periods of heavy rainfall the pipes become filled to capacity. That’s when a process called “combined sewer overflow” kicks in, activating outfalls from which the full pipes can spew sewage-contaminated runoff directly into the Susquehanna River."