What was the point of the shade balls in California?

[Gaebryel Quintyne]

Desalinization is expensive, and take a long time to ramp up production. Efforts in that direction are being made, but it's not something that can happen quick enough.

Here's a decent write up. http://ww2.kqed.org/science/2015/03/...ater-problems/

That explains so much. Thank you .