Andy Asberry wrote:
Water district pumps water from a lake 75 miles south to a local lake
405 feet higher. They propose to build a hydro generation plant on the
end of this pipeline before dumping it in the lake.

Am I missing something here?

What they are doing, is keeping power plants running at night when
demand is lower, to pump the water. During the day when they get peak
demands, they release water through turbines to generate electricty.
There are losses, but by using untapped capacity at night, they gain
capacity during high demand, for a lower overall cost than building
another power plant.

Jon