The influx of people heading to the swimming hole and resulting problems spilling into neighborhood yards has hit an all-time peak this year, Durand and fellow neighbors said. The last time a count was done by Friends of the Wissahickon, in 2011, upwards of 400 people would visit the pool on a summer weekend. McCarthy said unofficial anecdotal car and foot traffic estimates now suggest weekend turnout can be as many as 600. Residents say cars, many with out-of-state license plates, line their streets. And, for the first time, discarded needles are being found among the garbage people leave behind, police and neighbors say.