Mike
I have
Western Painted turtles, they are native to my area and, obviously adapted to our winter climate. I leave my turtles in the pond all year, even in the winter when they go dormant and sleep it out under the ice.
I had a look at
http://www.exotic-pe...es-for-sale.php and I can't say I'm familiar with any of those turtles they have listed for sale there, but I'll tell you what you probably should be looking for in a turtle for your pond.
* Look for a turtle who's native habitat and climate is similar to your pond and climate is like.
* Look for a small breed of turtle, and start out with as young a turtle as you can find. A big turtle in a small pond won't work out very well. You never did say how big your pond is???
* Try and find a turtle that is mostly vegetarian, at least as an adult, unless you don't mind buying more fish every once in a while.
* Find a breed of turtle that likes to bask in the sun. Some turtles spend almost all there time hiding under water,,, you might as well get a clam for a pet.
Monkeypie mentioned red eared sliders, I think they might be meet all the points I have listed.
Again I can't emphasize it enough, that turtles will wander, so you really need some sort of fence or barrier to keep them in and around your pond, especially since no turtle you get will be native to your area.