Just about any retention pond in the area will have them. The one by the old Circuit City HQ used to have a big snapper that liked to sun itself on the road, there were a few occasions where I had to pick that big thing up and move it so it wouldn't end up a speed bump. It's been years, but I hope it's still doing OK...

...side note, if you don't know how to handle snapping turtles, don't pick them up, they have an incredibly long range and will bite you...