Rick Smith took drone footage of this lovely beaver dam and pond in northern Minnesota. Beavers worked on this dam for seven years. Then it collapsed.
The water from the pond drained in about four hours. Smith said,
We own the property that this dam is built on and were totally heartbroken when this dam gave way. The beauty of this natural setting is why we bought the property in the first place. We had no part in the destruction of this dam. It merely could not take the pressure of two week of heavy rain draining into beaver pond flood plain. Also, the beavers built it too high, 9 Ft. It was an engineering marvel. Double decker beaver dams are not that common.
But the beavers didn't give up. Within six weeks of the collapse, they had rebuilt the dam to about four feet. Smith has another drone video showing their progress from May of this year. -via reddit