‘Shade Balls’ Roll their Way into the Spotlight

by Samantha Englert

This past summer you may have noted that social media has been flooded with pictures and videos of black balls blanketing several California reservoirs, somewhat reminiscent of a massive playground pit filled with black plastic balls. You were probably wondering, what exactly am I looking at? These floating objects have been referred to in the news as bird balls, conservation balls, reservoir balls and floating ball blankets, yet the biologist from the Los Angeles Department of Water and Power who developed this technology named them “Shade Balls.” So what are these Shade Balls?

Shade Balls are hermetically sealed four-inch floating balls made with carbon high-density polyethylene and partially filled with water; each costing 36 cents to manufacture. The carbon provides the ball with its black color. The sphere shape of the ball helps adapt it to any water body, including tanks. Polyethylene, though a plastic, is safe contact with potable water, the same plastic used to purchase most supermarket drinks, without BPA or other toxic materials leaching into these balls.

Shade Balls are commonly employed on local reservoirs during droughts to reduce water evaporation by nearly 75 percent, and to save water replenishment costs. The carbon in the balls absorbs sunlight to prevent algae growth. They also decrease the solar carcinogen bromide, a natural element typically in groundwater, into the carcinogen bromate. Shade Balls have a life expectancy of about ten years.

Shade Balls also reduce fuel costs in heated tanks, acting as a floating insulation blanket. Perhaps the only negative concern with Shade Balls is that birds and other wildlife may be deterred from using the ponds, reservoirs and lagoons that are shielded with the balls. What if all reservoirs or ponds in dry climates were to use Shade Balls? What would become of our wildlife in these regions?


Howard, Brian. Why Did L.A. Drop 96 Million ‘Shade Balls’ Into Its Water? National Geographic. Aug 12, 2015. [http://news.nationalgeographic.com/2015/08/150812-shade-balls-los-angeles-California-drought-water-environment/]

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