They certainly can be disastrous in ecological terms, and will disrupt all biotopes along the concerned water flows.

But it's extremely renewable none the less.

Reminds me of when Bjork was protesting the construction of a new hydropower plant in Iceland, when the Director of Iceland's National power company (behind the project) was actually her uncle. I used to be romantically involved with someone in his side of the family and noticed Bjork was conspicuously absent from any family gatherings he hosted, of which there were many.