Turtles!

It's an introduced species (or technically, subspecies) in a lot of places in part because it used to be widely sold as a pet. They're sold when they're like an inch or so long (carapace length) but then when they grow too big people get rid of them in various ways, including just putting them in nearby waterways.

The species is also pretty capable in the wild, which is why breeding populations of them are everywhere.

I'm down in Florida and the state banned the sale of them in the pet trade years ago. Yet they're still the herping equivalent of trash-tier commons in suburban lakes and canals.

Edit: Actually, it's a subspecies. Pond sliders are Trachemys scripta, and red-eared sliders specifically are Trachemys scripta elegans.