I've got a couple...used to be fairly aggressive about getting them out. Less so in the last few years. Based on what I've read they aren't much of a hazard to healthy fish. They certainly do a nice job keeping the ponds clean of carcasses though.
During the spring migration you'll see them crossing the roads out in the country...picked one up last spring with a shell about as big around as my arms would go. Moved her (likely a 'her' but not positive) across the direction she was going after showing the kids. Gotta love nature.