Can you borrow a dog from a friend for a few days? It's worth a try.

We have a beach at a local lake that our town uses for swimming. We have had a Canadian Goose problem there for years, and they use dog patrols as well as some sort of goose repellent that they spray on the sand...not sure what it's called.

Call your local environmental protection/wildlife management agency...they may have some sort of solution for you too.