Just south of the Bay Area, you can see such a facility on the road between the 101 and the 5, at Pacheco Pass.
http://en.wikipedia.org/wiki/San_Luis_Reservoir
See also : http://en.wikipedia.org/wiki/Pumped_storage
Just south of the Bay Area, you can see such a facility on the road between the 101 and the 5, at Pacheco Pass.
http://en.wikipedia.org/wiki/San_Luis_Reservoir
See also : http://en.wikipedia.org/wiki/Pumped_storage