Canals were a place to play, fish, swim, picnic, even water-ski behind a car on the bank.For the few stands of trees remaining today, though, many more miles of canal sit mostly forgotten.They are pathways for some who commute by foot or bicycle, a workplace for a few water-wranglers, and ignored by most others.Amid the gnarled roots of history and the weedy present, some in Phoenix see the canals