"oh and dams (at least small onces) arent necessarily all that bad, the beaver actually enhances the environment by building dams"

Whoa there Guest Petr. You sure don't work for the Department of Natural Resources in our state. One of their favorite pastimes is removing those little dams you're so fond of,whether man-made or beaver made. Their reasons for doing so are legion and include the dams causing alteration of natural flow patterns,fragmentation of habitat,blockage of migration corridors, degradation of water quality, alteration of temperatures and oxygen levels, fluctuation of water levels causing either stranding or flooding of fish and wildlife, and the list goes on and on.

Environmental enhancement? They sure don't think so.