So sorry, Tink.
There are a lot of things you can do, but nothing works 100%. There are people who wind fishing line around upright posts along the banks, to make it hard for the bird to walk. You can suspend some of the fishing line, too, so the bird can't fly down because its wings get tangled in the line.
There are fake snakes, fake owls, fake things that move, water spitting things activated by the bird's motion, all sorts of stuff.
I think your dogs are your best bet.