Millions of ‘Shade Balls’ to Prevent Evaporation in California Reservoirs

posted: 08/12/15
by: Danny Clemens
Shade ball deployment
Los Angeles Department of Water and Power

Los Angeles officials have come up with a surprisingly low-tech way to fight the region's water crisis: millions of floating plastic balls.

As part of a $34.5 million project, the city's Department of Water and Power has released nearly 100 million of so-called "shade balls" into three local reservoirs in recent months. The layer of balls protects water from algae formation, dust, rain and wildlife.

Perhaps more importantly, the black balls also help to prevent evaporation. According to Los Angeles Mayor Eric Garcetti, the balls could conserve 300 million gallons of reservoir water each year -- water that California desperately needs.

On a chemical level, the balls prevent the production of bromate, a suspected carcinogen. Bromate forms when naturally occurring bromite reacts with added chlorine and sunlight.

Shade balls will likely become a permanent fixture atop reservoirs. This particular batch will be deployed for decade, after which time they will be removed, recycled and replaced.

"LADWP's innovative use of shade balls will protect our water supply and ensure that residents have access to clean, safe, and ready-to-drink water. As we work to ensure a more sustainable and resilient future for L.A., I look forward to more creative, trailblazing and cost-effective solutions," Los Angeles Councilmember Felipe Fuentes, chair of the city's Energy and Environment Committee, said in a news release.


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