If the duck has been there for years, as the woman claims, someone is feeding it out of a container. I know of ducks and a goose in a city park that lived for many years, with bills like that, because they were fed daily out of a container. Ducks with bad legs can also do okay in parks where they are in the water most of the time. The fact she wouldn't even take $100 for the duck must mean it does mean a lot to her and her daughter. It's obviously not all about selfishness. Have you ever taken care of ducks in a park every day, including crippled ones? If not, you might want to get off your high horse.
This is not to discourage your mission to rescue ducks, but just a warning that ducks with injuries, both domestic and wild, can often end up euthanized, regardless if someone is offering to give them a home or not. Wild ones that cannot be fully rehabilitated in so many days will definitely be destroyed. Also, someone might decide no domestic ducks should be in any state park and have them all killed. No ducks should be running around with hooks in their mouths, however. Someone needs to catch those and get the hooks out.
So, you can risk going above her head or not. Just don't expect the results you want will be the results you get. There's also the local newspaper, if you still have one, but once again, the press attention may not have the results you want. Ducks can survive in all sorts or locations, some far from perfect. Even in perfect type homes, though, they can be killed one way or another long before they reach old age, as many can testify here.
