Sure he dug a ditch etc. But he also built a house; that's more disruption than this whole process surely? And by reducing the water velocity, he reduces erosion potential. I think this might be very eco-friendly depending on the site.
Not saying it's really bad, just saying it's not good.
Think of it as, what if his 40 neighbours did it?
It's like using wood to power you house in the forest. If it's juts you the harm is hard to see and not huge in the scheme of things, but it is harm and if everyone did it that's really bad.
> And by reducing the water velocity
This is a bad thing that's part of the issue, your removing energy from the stream which changes it's dynamics.
But compared to the house, yep perhaps not to bad.
