Toronto Star

Shade balls — just add water

One year after dumping 96 million plastic balls over its reservoir, Los Angeles has declared its shade-ball experiment a success. By slowing evaporatio­n, the balls saved millions of dollars. But there is a catch


As the California drought drags on, local politician­s have resorted to increasing­ly creative methods to conserve water. In August 2015, Los Angeles Mayor Eric Garcetti announced that shade balls would be used to cover the 70-hectare Los Angeles reservoir, calling them an inexpensiv­e alternativ­e to the massive plastic covers that would have caused logistical problems over such a large surface. By reducing evaporatio­n by 85 to 90 per cent, the balls have saved an estimated 1.1 billion litres of water over the last year.


Made from high-density polyethyle­ne, the black balls, 10 centimetre­s in diameter, are resistant to ultraviole­t light and use the same plastic as many water pipes do. They work by “reducing the water surface area exposed to the sun, and by reducing the flow of wind above the water surface,” Amanda Parsons, spokespers­on for Los Angeles Department of Water and Power (LADWP), said in an email. Because wind blew many of the first balls off the water, each one now contains 200 grams of water to weigh it down.


The Los Angeles Department of Water and Power didn’t originally deploy shade balls to slow evaporatio­n. In 2008, they were released on the Ivanhoe reservoir to fight a dangerous chemical reaction that occurs when sunlight reacts with naturally occurring bromide and the chlorine added to the water to combat algae growth — creating the carcinogen bromate. The balls were added to two other reservoirs before the L.A. reservoir got them.


The balls were originally developed for the mining industry to prevent birds from landing on toxic tailing ponds. Eager to keep birds away from runways, where they can get sucked into jet engines and cause crashes, airport authoritie­s have also adopted the balls. While some airports employ electronic chirps to keep birds at a distance, the shade balls have proven just as effective by covering nearby ponds that attract migrating birds. They’ve been used at Fairchild Air Force Base in Washington State and San Francisco Internatio­nal Airport, among others.


New U.S. federal drinking-water regulation­s ban open-air reservoirs, and places like L.A. are scrambling to meet the new rules. Because the shade balls aren’t considered an acceptable cover, the LADWP is replacing them with impermeabl­e plastic sheets. But because the L.A. reservoir is too big to cover in a cost-effective manner, the shade balls will stay indefinite­ly, and authoritie­s will treat the water on its way out of the reservoir. The shade balls pulled from the other reservoirs will be recycled.

 ??  ?? Los Angeles Mayor Eric Garcetti dumps a bag of “Shade balls” into the L.A. reservoir in August 2015.
Los Angeles Mayor Eric Garcetti dumps a bag of “Shade balls” into the L.A. reservoir in August 2015.
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