When naturally occurring bromite and disinfecting chlorine combine chemically under the sun in Los Angeles reservoirs to form cancer-causing compounds and foster algae, there is only one economical way to combat the menace—unleash the shade balls.

The media hasn’t had this much sport saying suggestive things about balls since, well, they haven’t really stopped chortling about them at all since someone let the air out of New England Patriot quarterback Tom Brady’s pigskins in Deflategate.

On Tuesday, the Los Angeles Department of Water and Power (DWP) capped off dumping the last of 96 million black plastic balls partially-filled with water into the Los Angeles Reservoir. The two-year, $34.5-million program is a way to preserve the 175-acre reservoir, cut cleaning costs and even save a little water (300 million gallons a year) by preventing evaporation. The shade balls, which can last 25 years, are chemically coated to block ultraviolet light.

Shade balls are not exactly new. They have been used to control odors at wastewater treatment plants and vapors in industrial ammonia tanks. They’ve slowed evaporation at petroleum facilities, and kept birds away from toxic tailing ponds near mines and out of water near airport runways.

The U.S. Environmental Protection Agency (EPA) got tough on storing drinking water in open air reservoirs in 2006 and ordered them phased out for health reasons. The LADWP responded by dumping 400,000 shade balls in the Ivanhoe Reservoir in 2008 and capped three others.

It was said to be the first time a major utility had deployed shade balls to solve a water-quality problem. Ivanhoe eventually got 3 million balls, but is expected to be phased out as a drinking-water reservoir soon.

Tuesday’s final dump of 20,000 shade balls in the Los Angeles Reservoir was graced with the presence of L.A. Mayor Eric Garcetti, who said, “In the midst of California’s historic drought, it takes bold ingenuity to maximize my goals for water conservation. This effort by LADWP is emblematic of the kind of the creative thinking we need to meet those challenges.”

Three hundred million gallons of water supplies 8,100 people with water for one year.

–Ken Broder

To Learn More:

Who’s Behind the 96 Million “Shade Balls” That Just Rolled into L.A.’s Reservoirs? (by Eric Roston, Bloomberg)

Garcetti, Officials Release 20,000 Shade Balls Into L.A. Reservoir (City News Service)

Shade Balls Are California's Most Mesmerizing Water-Saving Trick (by Brad Plumer, Vox)

Plastic Balls Protect California Reservoirs (by Catherine Kavanaugh, Plastics News)

A Reservoir Goes Undercover (by Francisco Vara-Orta, Los Angeles Times)