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

Why does Reservoir have 100 million black balls?

Califronia Put 96,000,000 Black Balls Into Water, Result is Insane!

S.mouse - Black Balls

Can you swim in shade balls?

My Neighbor’s Big Black Balls

They Dumped 96 Million Black Balls Into LA's Reservoir — 10 Years Later, Nobody Expected This