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 (DWP) to meet U.S. Environmental Protection Agency water-quality requirements.
They have the added perk of aiding with the ravages of the drought, and are expected to keep about 300 million gallons annually from evaporating.
"In the midst of California's historic drought, it takes bold ingenuity to maximize my goals for water conservation," Mayor Eric Garcetti said in a statement, noting that the effort is "emblematic of the kind of the creative thinking we need to meet those challenges."
The 36-cent balls also will help prevent evaporation of 300 million gallons of water annually from the 3.3 billion-gallon reservoir, the DWP said.
