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 penetrating¹ the 175-acre surface of the reservoir.

 

That prevents chemical reactions that can cause algae² blooms and other problems, allowing the Department of Water and Power (DWP) to meet U.S. Environmental Protection Agency water-quality requirements.

 

They have the added perk³ of aiding with the ravages⁴ of the drought, and are expected to keep about 300 million gallons annually⁵ from evaporating.

 

"In the midst of California's historic drought, it takes bold ingenuity⁶ to maximize my goals for water conservation," Mayor Eric Garcetti said in a statement, noting that the effort is "emblematic⁷ of the kind of the creative thinking we need to meet those challenges."

 

The 36-cent balls also will help prevent evaporation⁸ of 300 million gallons of water annually from the 3.3 billion-gallon reservoir, the DWP said.

 

The city began using shade balls in 2008.

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