I wouldn't....
I walk my 2 big ducks around our community pond, but its small, we have the same 'pond ducks' that live there all the time, its a controlled enviroment and there is no risk of a stray dog attacking from the bushes. Even then I lost control of the duckling a couple months ago and had to wade out there to catch the "hairy beast" before she got in trouble with a large turtle or one of the dom drakes...
My big ducks are big enough to deal with the other ducks, so I don;t worry much there. They love the water and I enjoy watching. BUT, if it were a pond that was open to the public or had other wild animals hanging around I would'nt allow my ducks in there just because they could get a wild hair and run off briefly as they DO like to explore, and they DO get distracted easily, and that could lead to trouble if they were too far away from me and something happened.
Your ducks will be just as happy playing with you in your yard with a water hose. When we can;t go to our pond I'll put the big ducks in the bathtub for an hour just so they can float around and relax a little...as long as they can scoot under and splash around a little bit they're tickled pink.