Well my father worked for a water company. A very small part of the business was energy production, obviously they are managing resources like lakes anyway. Peak power capacity sells at a premium, thats why you can be sure it is used where its easy to do so. To just flick a switch and sell 1mw of energy for an hour could earn alot I imagine and justify upkeep for all the times it sits collecting rain?
Im pretty sure power companies do it but only in minority nationally, nuclear is incredibly cheap when done right. They could use tidal power, I live a few miles from one of the largest tidal ranges in the world; if Brunel was still alive he'd do it
On a smaller scale, I dont know. I think a watermill setup is small scale already, this device above is remarkable
do you live next to a river ?
Is does require a gradient though, alot of places I know the river/stream is flat. However they could dig it out but then you got the green brigade objecting to your interference