Shade balls are small plastic spheres floated on top of a

reservoir A reservoir (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation. Reservoirs can be created in a number of ways, including contro ...

for environmental reasons, including to slow

evaporation Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase. High concentration of the evaporating substance in the surrounding gas significantly slows down evaporation, such as when humidi ...

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 Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...

from landing on 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.Marco Chown Oved
"Shade Balls – Just Add Water"
''Toronto Star'', October 23, 2016
/ref> They have also been used by airports to prevent birds from being attracted to nearby drainage ponds thus reducing collisions with planes.

Usage by LADWP

Ivanhoe Reservoir view from north 2015-10-11

Starting in mid-2009, the

Los Angeles Department of Water and Power The Los Angeles Department of Water and Power (LADWP) is the largest municipal utility in the United States with 8,100 megawatts of electric generating capacity (2021-2022) and delivering an average of 435 million gallons of water per day to more ...

(LADWP) put about 400,000 balls in the Ivanhoe reservoir with the main objective of preventing the formation of a

carcinogen A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive substan ...

ic chemical,

bromate The bromate anion, BrO, is a bromine-based oxoanion. A bromate is a chemical compound that contains this ion. Examples of bromates include sodium bromate, (), and potassium bromate, (). Bromates are formed many different ways in municipal drinki ...

, which forms when sunlight interacts with naturally occurring

bromine Bromine is a chemical element with the symbol Br and atomic number 35. It is the third-lightest element in group 17 of the periodic table (halogens) and is a volatile red-brown liquid at room temperature that evaporates readily to form a simila ...

and the

chlorine Chlorine is a chemical element with the Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate betwee ...

added to prevent algae growth. In the original release by the LADWP, there is no mention of

water conservation Water conservation includes all the policies, strategies and activities to sustainably manage the natural resource of fresh water, to protect the hydrosphere, and to meet the current and future human demand (thus avoiding water scarcity). Populati ...

as an objective and the project was planned for a five-year life span, until a

Griffith Park Griffith Park is a large municipal park at the eastern end of the Santa Monica Mountains, in the Los Feliz neighborhood of Los Angeles, California. The park includes popular attractions such as the Los Angeles Zoo, the Autry Museum of the Ameri ...

project was completed. The reduction in evaporation led to an estimated savings of about of water in one year. In 2014 and 2015, the LADWP put 96 million shade balls onto its largest reservoir (Las Virgenes) in response to the

United States Environmental Protection Agency The Environmental Protection Agency (EPA) is an independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it be ...

's surface water treatment rule, which requires large reservoirs of treated water to be covered. The LADWP says that in addition to reducing evaporation, they also reduce UV radiation by-products and algae growth. 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.

Construction

The shade balls used in the Los Angeles project are made of

high-density polyethylene High-density polyethylene (HDPE) or polyethylene high-density (PEHD) is a thermoplastic polymer produced from the monomer ethylene. It is sometimes called "alkathene" or "polythene" when used for HDPE pipes. With a high strength-to-density ratio, ...

(HDPE) with

carbon black Carbon black (subtypes are acetylene black, channel black, furnace black, lamp black and thermal black) is a material produced by the incomplete combustion of coal and coal tar, vegetable matter, or petroleum products, including fuel oil, fluid ...

additive to protect the plastic from

ultraviolet Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nanometer, nm (with a corresponding frequency around 30 Hertz, PHz) to 400 nm (750 Hertz, THz), shorter than that of visible light, but longer than ...

radiation.Shade Balls: Sustainable Drought Prevention
, retrieved 3-31-2016, Precision Plastic Ball Adding carbon black also prevents the formation of

, a suspected human

. They are about 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.

References

External links

* * {{YouTube, uxPdPpi5W4o, Video "Why Are 96,000,000 Black Balls on This Reservoir?" Balls Water supply infrastructure Reservoirs