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

To find out why they are there, I navigated a boat through 96,000,000 black plastic balls on the Los Angeles reservoir. The initial claim made concerning shade balls was that they lessen evaporation. It transpires nevertheless that this was not the motivation behind their introduction.

Thank you so much to LADWP for organizing this unique tour for me. Let's mount the GoPro on the submersible the next time!

The balls float on the surface of the reservoir even if they break apart because they are constructed of high density polyethylene (HDPE), which is less dense than water. They have a diameter of 10cm (4 inches) and 210ml of water are inside. They are there primarily to prevent sunlight from penetrating the water,
So their primary purpose is to prevent sunlight from penetrating the water and starting a chemical reaction that would otherwise transform innocuous bromide into hazardous bromate. Regulators demand that bromate levels be maintained below 10 micrograms per liter on average over a 12-month period because this effect develops with sustained exposure to bromate.

Special thanks to Donal Botkin, Michael Krugman, Ron Neal, Stan Presolski, Terrance Shepherd, Penward Rhyme, and everyone who offered suggestions on an early version of this film for Patreon supporters.

The Las Virgenes Reservoir provided the video of the first shade ball dump.
Euro-Matic for film of a bird in a jet engine

Produced and researched by Casey Rentz

Maria Raykova's animated shorts

music available at epidemicsound.com "Seaweed" from "Colorful Animation 4"

"Marty Got a Plan" by Kevin MacLeod is also cited.

This video explains the science behind water quality.