LOS ANGELES (AP) – The city of Los Angeles has completed a program of covering open-air reservoirs with floating “shade balls” to protect water quality.
City officials this week dumped the last 20,000 of 96 million black balls into the Los Angeles Reservoir in Sylmar, 25 miles northwest of downtown.
The 4-inch-diameter plastic balls block sunlight from penetrating the 175-acre surface of the reservoir.
That prevents chemical reactions that can cause algae blooms and other problems, allowing the Department of Water and Power to meet U.S. Environmental Protection Agency water-quality requirements.
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The utility says the 36-cent balls also will help prevent evaporation of 300 million gallons of water annually from the 3.3 billion-gallon reservoir.
The city began using shade balls in 2008 and they now also cover the Upper Stone, Elysian and Ivanhoe reservoirs.