The rodents dug holes in the middle and at the same time plugged the overflow ditch. It's really more than a ditch, being more of a gully.
It doesn't look like much of a beaver dam, but this is about 6 or 7 feet deep.
I wish I had some tnt. I have to clear the overflow enough so that the water gets down below the breach or the whole dam will be gone in a few days. Of course I don't have any heavy equipment like a back hoe on tracks. There used to be a backhoe for the antique 420 JD crawler, but for some reason Dad sold it for scrap rather than buy a few new hoses. We are going to see what we can do by hand tomorrow. The beavers will probably fix it the next night. If I can keep the water below the breach until the summer, I can fix the breach.