There was once a little farm with many animals. The farmer, Justin, discovered his man-made lake that had a drain was beginning to clog. Justin did all that he could do to unclog but somehow the drains would magically clog up again the next day. He set traps.. nothing.. hired pest control.. nothing. Nothing is did seemed to work until one day he saw the annoying drain-clogger up people in action. Turns out they were not people... THEY WERE BEAVERS.
The reason why Justin was so worried about his lake being clogged was because he had farm animals that drank from that lake and bathed in that lake. The animals would stand in the water since it wasn't too high but as long as the beavers continue to work, the lake would soon get higher and higher to the point of the animals wanting nothing to do with the water.