Black balls — dealing with drought

Evaporation is a major cause of water loss from dams — as much as 40%¹. As of Monday, the Los Angeles Reservoir is protected from evaporation by 96 million black plastic balls. By this measure, evaporation is expected to be reduced by nearly 300 million gallons annually.

How does this work? Hollow black balls floating on the surface shade the water from the Sun, & reduce exposure to the air.

Other benefits include suppression of algal growth & under certain circumstances, sunlight driven reactions involving bromine & chlorine, to form carcinogens.
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¹ National Program for Sustainable Irrigation: “Controlling evaporation losses from farm dams“, http://lwa.gov.au/products/pf050873 / Los Angeles LA Angeleno black plastic balls floating LA Reservoir dam massive water source ball pit drought-stricken water clean protect it from evaporation LA mayor Eric Garcetti shade balls Los Angeles Reservoir final stage city city’s water quality protection plan costing $US34.5 million shade ball water-cleaning device reduces evaporation protects against animals dirt costs 36 cents 96 million 175-acre reservoir 3.3 billion gallons of water water quality control shade balls staving off algae growth preventing harmful chemical reactions sunlight chlorine shade balls cost-effective reduce evaporation nearly 300 million gallons per year provide drinking water 8,100 people onyx-coloured buoyant ball pit anti-drought measures Los Angeles Department of Water and Power $US100 million ultraviolet water treatment facility keep LA water safe help cut losses drought /