Comment by vidarh

Looking at a few of them, a few obvious problems are apparent.

Firstly, it takes a rather liberal idea of how close the basins need to be to each other to be viable.

Secondly, most of the ones I looked at would require extensive relocation of existing populations and/or large-scale infrastructure changes, such as re-routing important roads.

The first few I looked at also do not have a sufficient water supply nearby - you'd face either covering them or you'd quickly run into problems of evaporation that you have little ability to replenish/replace.

A lot of the ones I quickly looked at would also face "fun" issues such as no nearby infrastructure such as roads to bring in construction materials.

I have no idea how many suitable locations there are on that map, but it seems pretty apparent it is a small fraction of the ones marked before you even consider how many would be politically unviable because of public resistance to the environmental destruction.

To be clear, I'm not at all opposed to investigating pumped storage, but it's also not nearly that simple.