In 2002 the X Games were in Philadelphia and I saw the pros wakeboard in the SchuylkillRiver. The water looked shallow, scummy and nasty, just like you'd expect an inner-city river to be in a 200+ year old city. I've read some postings here about people who wakeboard way up the Schuylkill River somewhere where the water is supposed to be cleaner, but good luck. I know Jeff Barton has a wakeboard operation happening just outside of Philadelphia.
www.rideecs.com Be sure to tell Jeff I sent you. Finally, Liquid Sports Authority is in Pensauken, NJ and you can call them at 856-488-9443.