I remember reading an anecdote about beaver dam. A farmer found a beaver dam n his backyard one day. He brought over pick shovel, ax etc and broke up the dam. He forgot his tools in the back yard. Next day he came to the back yard, the beaver dam was fully rebuilt, it was like new, with one difference. The pick, shovel, ax, spade etc., the tools that the farmer forgot in the back yard, were now part of the beaver dam, they were built into the dam.
Incidentally there is a large beaver dam in McGregor Point Provincial Part in Ontario, it has formed a rather large lake and influenced the ecology of a large region surrounding it. They have built a tower from which the effects of the beaver dam may be viewed.