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

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May 10, 2019


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


  • these are shade balls they're being dumped into this water reservoir in Los Angeles
  • and contrary to what you may have heard their main purpose is not to reduce evaporation
  • so what are they really for? To find out I am visiting the largest collection of these balls anywhere on Earth at L.A. reservoir
  • 96 million shade balls. That's correct. 96 million it's very rare for you to see 96 million of anything
  • This is your life vest which you are required to wear. Alright.
  • Throw your leg over and climb on in anyway you can
  • there you go. Thank you
  • looking at this I had so many questions. Like why are they black? Are they safe to have in drinking water?
  • How much do they cost? Do they actually reduce evaporation? And what is their real purpose?
  • is it hard to drive in shade balls. It is very hard. Why is that?
  • These are actually partially filled with water the reason they're filled with water is that in L.A reservoir we have some really high winds
  • and so if we didn't put water in these things there'd be balls bouncing on the 5 freeways people would drive down they'd be all over the place
  • so these keep the balls in the reservoir and if they do start to roll they kinda wobble because of water makes them uneven
  • but that makes them significantly difficult to push out of the way especially when they form close-packed crystal like structures
  • behind the boat the balls quickly come together in our wake
  • and some close to the motor are pulled along with boat
  • wow
  • did you what did you think the first time they suggested doing this or when it first came in
  • yeah it was a little out there. did you think they were nuts? No, not nuts
  • it just like. It looks absurd
  • It's like we're in the world's biggest ball pit
  • yeah right that's what it looks like you can't tell by standing here that we're actually floating over
  • I think it's probably 40 50 feet right here, 40 50 feet deep below us
  • and you can't even see any water
  • you'd think it was a joke. Right?
  • if you didn't know. You'd would be like no you're not that's like a green screen or something alright yeah it's fake
  • so like when i switch on my tap at home is the water coming from here?
  • Yes. Sometimes, or always. Most of the times
  • Most of the time the water is coming from here, absolutely nuts
  • so why is LA reservoir covered in shade balls?
  • the problem all started with Bromide
  • Bromide is a naturally occurring substance associated with salt water
  • and so normally places like the California aqueduct that comes down from the delta
  • you get some salt water intrusions we have some bromide in the water
  • bromide is harmless and it's almost impossible to remove
  • and when you disinfect the water with ozone, that bromide becomes bromate
  • and bromates are carcinogenic
  • and so around year 2000 they wrote regulations regulating bromate
  • and the regulations basically said if you have a treatment plant that uses ozone
  • then you have to watch bromate to be careful not to form to much
  • so the only place we ever measured bromate was in our filter plant
  • and the results were always within 10 micrograms per liter limit set by regulators
  • so they were confused when they got a call from one of their customers a beverage company in L.A
  • they said we have some really high levels of bromate showing up are you aware of this?
  • and we said well we don't show anything
  • but between the filtration plant and the customer was the reservoir
  • so they did some tests
  • almost immediatly upon coming into this open reservoir the bromate levels jumped
  • it turned that bromide with chlorine which is supposed to be safe in bright sunlight form bromate even more than ozone
  • and so we made this unfortunate scientific discovery that actually wasn't a part of any regulatory scheme
  • and so here we are at reservoir
  • we have water source that's got bromide in it harmless
  • we have chlorine, we have to have disinfected water, we have sunlight because it is open
  • the only choice we have is to remove sunlight
  • so we looked at all sorts of things
  • we looked at floating tarps across the water
  • and normally we put a floating cover on the water but that's a multi-year project
  • and so we said can't we manufacture kind of trampoline with poly like PVC pipe
  • they're just gonna become bird perches, it'll have a big water quality problem
  • and so we knew we had high density polyethylene pipe which is used in the water industry
  • and we know that it floats and we at one point thought about can we get to float a pile of pipe across the surface
  • well that's hard to do and very expensive because it's a lot of material
  • so maybe we could take some pipe and run it through a chipper and we can make a debris field across the surface
  • like the back corner of a lake somewhere
  • but in anyhow all this mushy warm water with plastic floating on the top that sounds like a petri dish
  • and so lo and behold Dr Brian White did some research and he found the shade ball
  • except they weren't called shade balls at the time
  • this product existed and they were called bird balls
  • and they'd use it on ponds that had mine tailings where they didn't want waterfowl to go in and get poisoned
  • and also around airports where there were ponds and they wanted to keep the waterfowl off so that they didn't take off and get into the jet engines

Download subtitle


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. This effect occurs with prolonged exposure to bromate so regulators insist that levels be kept below 10 microgram per liter on average over a 12 month period.

Special thanks to Patreon supporters:
Donal Botkin, Michael Krugman, Ron Neal, Stan Presolski, Terrance Shepherd, Penward Rhyme and everyone who provided feedback on an early draft of this video.

Thanks to:
Las Virgenes Reservoir for footage of initial shade ball dump
Euro-Matic for bird into jet-engine footage

Researched and Produced by Casey Rentz

Animations by Maria Raykova

Music from http://epidemicsound.com "Colorful Animation 4" "Seaweed"

And from Kevin MacLeod "Marty Gots a Plan"

This is an educational video about the science of water quality.

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