Get a larger animal and release it nearby. One that hunts beavers. Like maybe a wolf. Or a Jaguar. Or maybe something that makes wolf/jaguar noises will drive it away. Or wolf piss, I've seen that at some stores. Or maybe something that generates the calls made by large predatory birds. No wait, get a large snake that will hunt in the water, like an Anaconda. Then, later get a mongoose to hunt/kill the Anaconda to get rid of it.