Some people (mostly the same that think global warming isn't happening, then that it's not our fault then that there's nothing we can do - anything to justify n

Some people (mostly the same that think global warming isn't happening, then that it's not our fault then that there's nothing we can do - anything to justify not changing our behavior basically) like to complain that beaver dams can't be good for the environment if human dams are bad for environment. The main difference is that human dams usually require the river to be regulated, whereas beaver dams make river move around, and after a few years the dams move as well, changing the riverbed again. This cycle repeats, and after a while beavers make the river change its bed dozens of times, creating a wide, green marsh, storing lots of water in shaded, green landscape, only small part of which is the current riverbed. It's also not a big obstacle for fish, because the dams leak, and change their positions every few years. So it does not stop fish migration and breeding significantly. We on the other hand create a narrow regulated riverbed and hard obstacles that stay in one place for decades. The bodies of water we create aren't shaded, so a lot of water is lost to evaporation. There's not much new plantlife (in fact it's usually a net loss when you account for the flooded area). The high water head creates a lot of pressure and accelerates the water downstream, contributing further to the desertification of the area.