A shade ball is a small plastic sphere floated on top of a

reservoir A reservoir (; ) is an enlarged lake behind a dam, usually built to water storage, store fresh water, often doubling for hydroelectric power generation. Reservoirs are created by controlling a watercourse that drains an existing body of wa ...

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.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 Public utility, utility in the United States with 8,100 megawatts of electric generating capacity (2021–2022) and delivering an average of 435 million gallons of wat ...

(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 agent that promotes the development of cancer. Carcinogens can include synthetic chemicals, naturally occurring substances, physical agents such as ionizing and non-ionizing radiation, and biologic agents such as viruse ...

ic chemical,

bromate The bromate anion, , 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 drinking w ...

, which forms when sunlight interacts with naturally occurring

bromine Bromine is a chemical element; it has chemical symbol, symbol Br and atomic number 35. It is a volatile red-brown liquid at room temperature that evaporates readily to form a similarly coloured vapour. Its properties are intermediate between th ...

and the

chlorine Chlorine is a chemical element; it has 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 between ...

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

water conservation Water conservation aims to sustainably manage the natural resource of fresh water, protect the hydrosphere, and meet current and future human demand. Water conservation makes it possible to avoid water scarcity. It covers all the policies, strateg ...

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 Amer ...

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 agency of the United States government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it began operation on De ...

'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 rati ...

(HDPE) with

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

additive to protect the plastic from

ultraviolet Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of ...

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