In southern Germany, not far away from the Lake of Konstanz, in the forest beneath a road up to the Heiligenberg, you can find the remains of a little water power station from the early times of electricity. There is no space for a barrier lake in the small valley (if there had been one, the building would have been on its ground), so there must have been a row of generators in the running creek. I have no idea, at which time this little power station has gone out of service, but i estimate, it was before the World War 2.

View through the main room, behind me the rows of insulators.