Why Are 96,000,000 Black Balls on This Reservoir?

I took a boat through 96 million black plastic balls in the Los Angeles tank to find out why they are there. The first time I heard about the shadow spheres, the claim was that they reduce evaporation. But this is not the reason why they showed up. Many thanks to LADWP for organizing this special tour for me. Next time we put the GoPro on the submarine!