The best way to deal with them is not going Elmer Fudd on them. That is probably illegal anyway, at least most of the year. The best duck deterrent is one that encourages them to find other waters peacefully. It turns out there are quite a few products on the market for just this type of problem. Duck deterrents can be divided as follows:
Scare Tactic – These include things like flare guns or cap guns which just make noise. Basically, you see ducks running amuck in your pond, you go outside and fire off a few rounds of something loud in their generally direction and consider the ducks repelled. A less expensive alternative, if you have a real gun, may be to shoot in their direction with blanks. The drawback to this is that ducks almost certainly have short memories and will most likely be back.
Electronics - This is like a scarecrow method which relies on electronic sensors to detect movement and then emit sounds which scare the ducks away. The problem with many of the devices is that it emits the same sound over and over and the ducks get used to it. If purchasing one of these devices, consider getting one that has multiple sounds or multiple variations of those sounds.
Physical Control – This would include fences or other barriers which prevent your duck population from reaching the water, or your yard from the water. The problem here, as you may have guessed, is that ducks fly which makes it almost impossible to block them from anywhere on your property. There are some manufacturers of devices which claim better success rates with carefully designed mechanisms. Roosting
Deterrents - Roosting deterrents are devices that prevent your ducks from sleeping. This is not the most common duck deterrent but if they are nesting in the same place each night, it may work.
Dogs - There is a good reason why dogs always chase ducks in movies, they love it. A good dog can really help weed out the local duck population. The problem here is that you are replacing one animal with another or several animals with one that is at least more manageable.
How do you get rid of ducks? We would love to know.