{{short description|Plastic balls used in reservoirs for environmental protection and evaporation reduction}} [[File:Schwimmbad-Abdeckung.jpg|300px|thumb|Shade balls covering a swimming pool at a hotel]]
A '''shade ball''' is a small plastic sphere floated on top of a reservoir for environmental reasons, including to slow evaporation and prevent sunlight from causing reactions among chemical compounds present in the water. Also known as '''bird balls''', they were developed initially to prevent birds from landing in bodies of water.
==History== Shade balls were originally known as ''bird balls'', as they were developed initially to prevent birds from landing on toxic tailing ponds produced by mining operations.<ref name="oved">{{cite news |first=Marco Chown |last=Oved |url=https://www.pressreader.com/canada/toronto-star/20161112/282952449774508 |title=Shade Balls – Just Add Water |work=Toronto Star |date=November 12, 2016 |access-date=August 22, 2025 |via=PressReader}}</ref><ref name="birdballs">{{cite news |url=https://www.governing.com/archive/gov-shade-balls-water-quality.html |title=L.A. Says Goodbye to 'Shade Balls' |work=Governing |date=November 23, 2015 |first=Elizabeth |last=Daigneau |access-date=August 22, 2025}}</ref>
They have also been used by airports to prevent birds from being attracted to nearby drainage ponds, thus reducing collisions with planes.<ref name="npr">{{cite episode |first1=Robert |last1=Siegel |first2=Richard |last2=Harasick |url=https://www.npr.org/2015/08/12/431959386/los-angeles-unleashes-shade-balls-to-protect-reservoir-water-quality |title=Los Angeles Unleashes 'Shade Balls' To Protect Reservoir Water Quality |date=August 12, 2015 |series=All Things Considered |station=NPR}}</ref>
===Usage by LADWP=== [[File:Ivanhoe Reservoir view from north 2015-10-11.jpg|thumb|Shade balls in the Ivanhoe Reservoir, 2015]]
Starting in mid-2009, the Los Angeles Department of Water and Power (LADWP) put about 400,000 balls in the Ivanhoe reservoir with the main objective of preventing the formation of a carcinogenic chemical, bromate, which forms when sunlight interacts with naturally occurring bromine and the chlorine added to prevent algae growth.<ref name="oved"/><ref>{{cite web|last=Vara-Orta|first=Francisco |title=A reservoir goes undercover|url=https://www.latimes.com/archives/la-xpm-2008-jun-10-me-balls10-story.html |website=Los Angeles Times|date=10 June 2008 |access-date=27 December 2015}}</ref> In the original release by the LADWP, there is no mention of water conservation as an objective and the project was planned for a five-year life span, until a Griffith Park project was completed. The reduction in evaporation led to an estimated savings of about {{Convert|1.1|e9l|e6gal|abbr=unit}} of water in one year.<ref name=oved/>
In 2014 and 2015, the LADWP put 96 million shade balls onto its largest reservoir (Las Virgenes)<ref>{{cite news |last=Poon |first=Linda |title=How a Giant Ball Pit Is Saving L.A.'s Water Supply |url=https://www.citylab.com/life/2015/08/la-covers-its-reservoirs-with-millions-of-shade-balls/401066/ |newspaper=Bloomberg |language=en |date=August 12, 2015}}</ref> in response to the United States Environmental Protection Agency's surface water treatment rule,<ref name="epa">{{cite web |date=2013-02-11 |title=Water: Long Term 2 Enhanced Surface Water Treatment Rule |url=https://www.epa.gov/dwreginfo/long-term-2-enhanced-surface-water-treatment-rule-documents |access-date=2015-08-13 |publisher=United States Environmental Protection Agency}}</ref> which requires large reservoirs of treated water to be covered.<ref name="npr"/><ref name="LA Times 2015-08-12">{{cite news |last1=Walton |first1=Alice |last2=Grad |first2=Shelby |url=http://www.latimes.com/local/lanow/la-me-ln-shade-ball-water-20150812-htmlstory.html |title=The 36-cent 'shade ball' that could save $250 million and keep L.A. water clean |work=Los Angeles Times |date=2015-08-12 |access-date=2015-08-12 |quote=Shade balls are used to protect water quality, prevent algae growth and slow evaporation from the city’s reservoirs.}}</ref> The LADWP says that in addition to reducing evaporation, they also reduce UV radiation by-products and algae growth.<ref>{{cite news |last=Walton |first=Alice |date=August 23, 2015 |title=L.A.'s shade balls go viral – but the Internet has mixed opinion |url=https://www.latimes.com/local/cityhall/la-me-balls-first-and-spring-20150824-story.html |access-date=24 August 2025 |work=Los Angeles Times}}</ref> The balls saved 1.7 million cubic metres of water from evaporating during their deployment from August 2015 to March 2017. However, they required 2.9 million cubic metres of water in their manufacture. Nevertheless, the balls have a lifespan of ten years, and the plastic may be reused after that.<ref>{{cite web |last=Starr |first=Michelle |title=These Shade Balls Were Supposed to Save Water, But There's a Big Problem |url=https://www.sciencealert.com/la-reservoir-shade-balls-manufacture-use-more-water-than-they-saved |website=ScienceAlert |date=23 July 2018 |language=en-gb}}</ref>
====Construction==== thumb|A single shade ball The shade balls used in the Los Angeles project are made of high-density polyethylene (HDPE) with carbon black additive to make the balls opaque and protect the plastic from ultraviolet radiation.<ref name="shadeballs">[http://www.precisionplasticball.com/shade-balls "Shade Balls: Sustainable Drought Prevention"]. Precision Plastic Ball. {{Webarchive|url=https://web.archive.org/web/20180808104252/http://www.precisionplasticball.com/shade-balls |date=2018-08-08 }}. Retrieved March 31, 2016.</ref><ref>{{Cite web |title=Los Angeles Reservoir Covered With 96 Million Shade Balls to Conserve Water Amidst Drought |url=https://abcnews.go.com/US/los-angeles-reservoir-covered-96-million-shade-balls/story?id=33038319 |access-date=2025-08-25 |website=ABC News |language=en}}</ref><ref>{{Cite web |last=Ferris |first=Robert |date=2015-08-13 |title='Shade balls' protect LA water supply during drought |url=https://www.cnbc.com/2015/08/13/shade-balls-protect-la-water-supply-during-drought.html |access-date=2025-08-25 |website=CNBC |language=en}}</ref><ref>{{Cite news |last=Wagner |first=Laura |date=2015-08-11 |title=LA Rolls Out Water-Saving 'Shade Balls' |url=https://www.npr.org/sections/thetwo-way/2015/08/11/431670483/la-rolls-out-water-saving-shade-balls |access-date=2025-08-25 |work=NPR |language=en}}</ref> Adding carbon black also prevents the formation of bromate, a suspected human carcinogen.<ref>{{cite web |title=Potassium Bromate (Group 2B) |url=http://www.inchem.org/documents/iarc/vol73/73-17.html |access-date=2008-03-09 |work=International Agency for Research on Cancer: Summaries and Evaluations |publisher=Canadian Centre for Occupational Health and Safety}}</ref><ref>{{cite journal |last1=Kurokawa |first1=Y |last2=Maekawa |first2=A |last3=Takahashi |first3=M |last4=Hayashi |first4=Y |date=July 1990 |title=Toxicity and carcinogenicity of potassium bromate – a new renal carcinogen |journal=Environmental Health Perspectives |publisher=Environmental Health Perspectives |volume=87 |pages=309–35 |doi=10.1289/EHP.9087309 |jstor=3431039 |pmc=1567851 |pmid=2269236}}</ref>
They are about {{convert|4|in|cm}} in diameter, and are partially filled with water to avoid being blown by wind. HDPE plastic is commonly used for food and beverage containers as well as water distribution pipes.<ref name=shadeballs/>
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== References == {{reflist|30em}}
== External links == {{commons category|Shade balls}} * {{YouTube|yafDaT7PmVY|Video of 2014 Shade Ball Deployment}} * {{YouTube|uxPdPpi5W4o|Video "Why Are 96,000,000 Black Balls on This Reservoir?"}} Category:Balls Category:Water supply infrastructure Category:Reservoirs