People are as natural as the other things. We're just smarter.Dams and the reservoirs they create are just another way humankind goes about fucking things up. Beavers build dams but they build them in the right places and create habitats for themselves and other animals. They manage what they create and they play a part in creating the diversity nature wants and it is all sustainable.
Humans, on the other hand, build stuff that breaks nature and went it breaks we end up doing even more damage , and our contribution to diversity, on this planet, is bullshit like men in dresses.