Shade balls?
They emerged from obscurity Tuesday morning on the Internet with all the markings of the buzzphrase of the year — the term for them is shady and enigmatic, and to stoke juvenile social media glee, it has the word "balls" in it. Yet they are dead serious.
The shade balls of Los Angeles are 4 inches (10 cm) in diameter, hollow, polyethylene orbs made by XavierC, of Glendora, California; Artisan Screen Process, of Azuza, California; and Orange Products, of Allentown, Pennsylvania. The Los Angeles Department of Water and Power has now dumped 96 million balls into local reservoirs to reduce evaporation and block sunlight from encouraging algae growth and toxic chemical reactions. The balls are coated with a chemical that blocks ultraviolet light and helps the spheres last as long as 25 years. Las Virgenes, north of LA, now uses shade balls, too.