What is Cobbs Creek?
A creek that runs through Haverford (in Delaware County, Pennsylvania) past the historic Grange estate, then becomes the border between Upper Darby Township and the City of Philadelphia. It then passes between the borough of Millbourne and philly before turning south past Fernwood Cemetery, again serving as the border between Upper Darby and Philadelphia. It then becomes the border between Yeadon borough and Philadelphia and continues south to border Colwyn and Philly. It flows into Darby creek at the Colwyn, Sharon Hill, and Darby township border lines. SEPTA's route 100 high speed trolly line (old P&W) runs next to it in Haverford and part of Upper Darby. The Cobbs creek parkway borders it for a while in Philadelpia as well as Cobbs creek park. SEPTA's Market-Frankford line borders the creek in the borough of Millborne.
I wouldn't want to take a dip in Cobbs creek, I think it's a super fund site!