You can't make electricity without water. I mean, you can, but you have to use things like "solar panels" or "wind turbines," and who's going to do that? (Lots of people, I guess, but that doesn't help my point.) A 2009 study suggested that half of the freshwater we use goes to energy production, boiled to create steam to turn turbines, or used to cool off reactors. When we run low on water -- or when the water gets too warm -- the ability to generate electricity declines or halts. (Except from wind turbines and solar panels; I'll just keep pointing that out.)
According to the International Energy Agency, the amount of water we use for energy is about to go up. A lot. From National Geographic:
The amount of fresh water consumed for world energy production is on track to double within the next 25 years, the International Energy Agency (IEA) projects. …
If today's policies remain in place, the IEA calculates that water consumed for energy production would increase from 66 billion cubic meters (bcm) today to 135 bcm annually by 2035.
That's an amount equal to the residential water use of every person in the United States over three years, or 90 days' discharge of the Mississippi River. It would be four times the volume of the largest U.S. reservoir, Hoover Dam's Lake Mead.