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

I took a boat through 96 million black plastic balls on the Los Angeles reservoir to find out why they're there. The first time I heard about shade balls the claim was they reduce evaporation. But it turns out this isn't the reason they were introduced.

Huge thanks to LADWP for arranging this special tour for me. Next time let's put the GoPro on the submersible!

The balls are made of high density polyethylene (HDPE) which is less dense than water so they float on the surface of the reservoir even if they break apart. They are 10cm (4 inches) in diameter and contain about 210ml of water. So the main reason they are on the reservoir is to block sunlight from entering the water and triggering a chemical reaction that turns harmless bromide into carcinogenic bromate.

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Imagine the hundreds, if not thousands, of birds who unsuspectingly land on what appears to be a solid black surface, or through instinct and smell seek water, only to get caught among the balls, unable to lift themselves off, eventually losing all strength and drowning.

And, isn't this stuff in bread?

Bad move California.