If the bottom of the pond has leaves and stuff for the turtles to climb into they will hibernate in the pond. You must be sure that the pond does not total freeze, then your OK. They do go to the bottom of the pond to hibernate. You must also make sure your turtles come from an environment that is cold if they are older, larger turtles. You may have problems with turtles from the South getting them to live and hibernate in a cold climate in the North.