Totally remember that pond from when I was a kid! It might even still be there. As for the alligator/crocodile, I think that might have been our bigger than life imaginations. Now that park's creepy for other reasons...
Does anyone remember - would be back in the early '60s - the little park on Mission behind the Museum... waaay in the back, kind of up a hill, there was a cement pond with (maybe it was my imagination?) a crocodile or alligator in it? I remember being creeped out by it but also felt sorry for it stuck way back there.
We also used to go to Gerstle Park for family picnics and roll down the hill and hike up to the ruins of the old house behind the tennis courts. And on hot days to the park in Larkspur on Magnolia (we called it "Dark Park" because it was cool & shady).
Favorite parks from childhood? We had seven kids and not much money, so parks were a big part of family entertainment. We had so many kids we could play baseball just with the family.