It must've been some other variety of alligators that I witnessed persistently hanging out in retention ponds, urban creeks, and marshes at the urban/ex-urban interface back when I lived in Florida, then. As dumb as promotional merch for an incarceration facility is (and I am with you 100% on that), it would be just as foolish to believe a) the gator population will materially suffer and leave due to the facility being there and b) they won't be present throughout the year...they may not be floating out in the middle of the water/chilling out on the bank in full view, but they'll be present. Besides...all that needs to exist for it to be a deterrent is the possibility in the mind of the detained that the danger is there. Sort of along the same line of thinking as, "Is the electric fence on, or is it off?"