Photos: Reservoir shade balls
Four-inch-diameter plastic "shade balls" are dumped into reservoirs and block sunlight from penetrating the surface of the reservoirs. That prevents chemical reactions that can cause algae blooms and other problems, allowing the Department of Water and Power to meet U.S. Environmental Protection Agency water-quality requirements.
Reservoir Shade Balls
The Los Angeles Reservoir is seen covered with 96 million black plastic balls in the Sylmar area of Los Angeles 25 miles northwest of downtown Wednesday, Aug. 12, 2015. The city has completed a program of covering its open-air reservoirs with floating, 4-inch diameter "shade balls" to protect water quality by blocking sunlight from penetrating the 175-acre surface of the reservoir, preventing chemical reactions that can cause algae blooms and other problems, (AP Photo/Damian Dovarganes)
APTOPIX Reservoir Shade Balls
The Los Angeles Reservoir is covered with over 90 million black plastic balls in the Sylmar area of Los Angeles Wednesday, Aug. 12, 2015. The city has completed a program of covering its open-air reservoirs with floating, 4-inch diameter "shade balls" to protect water quality by blocking sunlight from penetrating the 175-acre surface of the reservoir, preventing chemical reactions that can cause algae blooms and other problems. (AP Photo/Damian Dovarganes)
Reservoir Shade Balls
The Los Angeles Reservoir is covered with over 90 million black plastic balls in the Sylmar area of Los Angeles Wednesday, Aug. 12, 2015. The city has completed a program of covering its open-air reservoirs with floating, 4-inch diameter "shade balls" to protect water quality by blocking sunlight from penetrating the 175-acre surface of the reservoir, preventing chemical reactions that can cause algae blooms and other problems. (AP Photo/Damian Dovarganes)
Reservoir Shade Balls
Water flows into the Los Angeles Reservoir, which has been covered with 96 million black plastic balls in the Sylmar area of Los Angeles 25 miles northwest of downtown Wednesday, Aug. 12, 2015. The city has completed a program of covering its open-air reservoirs with floating, 4-inch diameter "shade balls" to protect water quality by blocking sunlight from penetrating the 175-acre surface of the reservoir, preventing chemical reactions that can cause algae blooms and other problems, (AP Photo/Damian Dovarganes)
Reservoir Shade Balls
Water flows into the Los Angeles Reservoir, which has been covered with 96 million black plastic balls in the Sylmar area of Los Angeles 25 miles northwest of downtown Wednesday, Aug. 12, 2015. The city has completed a program of covering its open-air reservoirs with floating, 4-inch diameter "shade balls" to protect water quality by blocking sunlight from penetrating the 175-acre surface of the reservoir, preventing chemical reactions that can cause algae blooms and other problems, (AP Photo/Damian Dovarganes)
Reservoir Shade Balls
Water flows into the Los Angeles Reservoir, which has been covered with 96 million black plastic balls in the Sylmar area of Los Angeles 25 miles northwest of downtown Wednesday, Aug. 12, 2015. The city has completed a program of covering its open-air reservoirs with floating, 4-inch diameter "shade balls" to protect water quality by blocking sunlight from penetrating the 175-acre surface of the reservoir, preventing chemical reactions that can cause algae blooms and other problems, (AP Photo/Damian Dovarganes)
Reservoir Shade Balls
The Los Angeles Reservoir is covered with over 90 million black plastic balls in the Sylmar area of Los Angeles Wednesday, Aug. 12, 2015. The city has completed a program of covering its open-air reservoirs with floating, 4-inch diameter "shade balls" to protect water quality by blocking sunlight from penetrating the 175-acre surface of the reservoir, preventing chemical reactions that can cause algae blooms and other problems. (AP Photo/Damian Dovarganes)
Reservoir Shade Balls
The Los Angeles Reservoir is covered with over 90 million black plastic balls in the Sylmar area of Los Angeles Wednesday, Aug. 12, 2015. The city has completed a program of covering its open-air reservoirs with floating, 4-inch diameter "shade balls" to protect water quality by blocking sunlight from penetrating the 175-acre surface of the reservoir, preventing chemical reactions that can cause algae blooms and other problems. (AP Photo/Damian Dovarganes)
Reservoir Shade Balls
The Los Angeles Reservoir is covered with over 90 million black plastic balls in the Sylmar area of Los Angeles Wednesday, Aug. 12, 2015. The city has completed a program of covering its open-air reservoirs with floating, 4-inch diameter "shade balls" to protect water quality by blocking sunlight from penetrating the 175-acre surface of the reservoir, preventing chemical reactions that can cause algae blooms and other problems. (AP Photo/Damian Dovarganes)
Reservoir Shade Balls
Water flows into the Los Angeles Reservoir, which has been covered with 96 million black plastic balls in the Sylmar area of Los Angeles 25 miles northwest of downtown Wednesday, Aug. 12, 2015. The city has completed a program of covering its open-air reservoirs with floating, 4-inch diameter "shade balls" to protect water quality by blocking sunlight from penetrating the 175-acre surface of the reservoir, preventing chemical reactions that can cause algae blooms and other problems, (AP Photo/Damian Dovarganes)
Reservoir Shade Balls
The Los Angeles Reservoir is seen covered with 96 million black plastic balls in the Sylmar area of Los Angeles 25 miles northwest of downtown Wednesday, Aug. 12, 2015. The city has completed a program of covering its open-air reservoirs with floating, 4-inch diameter "shade balls" to protect water quality by blocking sunlight from penetrating the 175-acre surface of the reservoir, preventing chemical reactions that can cause algae blooms and other problems, (AP Photo/Damian Dovarganes)
Reservoir Shade Balls
The Los Angeles Reservoir is seen covered with 96 million black plastic balls in the Sylmar area of Los Angeles 25 miles northwest of downtown Wednesday, Aug. 12, 2015. The city has completed a program of covering its open-air reservoirs with floating, 4-inch diameter "shade balls" to protect water quality by blocking sunlight from penetrating the 175-acre surface of the reservoir, preventing chemical reactions that can cause algae blooms and other problems, (AP Photo/Damian Dovarganes)
Reservoir Shade Balls
Water flows into the Los Angeles Reservoir, which has been covered with 96 million black plastic balls in the Sylmar area of Los Angeles 25 miles northwest of downtown Wednesday, Aug. 12, 2015. The city has completed a program of covering its open-air reservoirs with floating, 4-inch diameter "shade balls" to protect water quality by blocking sunlight from penetrating the 175-acre surface of the reservoir, preventing chemical reactions that can cause algae blooms and other problems, (AP Photo/Damian Dovarganes)
Reservoir Shade Balls
Water flows into the Los Angeles Reservoir, which has been covered with 96 million black plastic balls in the Sylmar area of Los Angeles 25 miles northwest of downtown Wednesday, Aug. 12, 2015. The city has completed a program of covering its open-air reservoirs with floating, 4-inch diameter "shade balls" to protect water quality by blocking sunlight from penetrating the 175-acre surface of the reservoir, preventing chemical reactions that can cause algae blooms and other problems, (AP Photo/Damian Dovarganes)
Reservoir Shade Balls
Water flows into the Los Angeles Reservoir, which has been covered with over 90 million black plastic balls in the Sylmar area of Los Angeles Wednesday, Aug. 12, 2015. The city has completed a program of covering open-air reservoirs with floating "shade balls" to protect water quality. The 4-inch-diameter plastic balls block sunlight from penetrating the 175-acre surface of the reservoir, preventing chemical reactions that can cause algae blooms and other problems. (AP Photo/Damian Dovarganes)
Reservoir Shade Balls
The Los Angeles Reservoir is covered with over 90 million black plastic balls in the Sylmar area of Los Angeles Wednesday, Aug. 12, 2015. The city has completed a program of covering open-air reservoirs with floating "shade balls" to protect water quality. The 4-inch-diameter plastic balls block sunlight from penetrating the 175-acre surface of the reservoir, preventing chemical reactions that can cause algae blooms and other problems. (AP Photo/Damian Dovarganes)
Reservoir Shade Balls
The Los Angeles Reservoir is covered with over 90 million black plastic balls in the Sylmar area of Los Angeles Wednesday, Aug. 12, 2015. The city has completed a program of covering open-air reservoirs with floating "shade balls" to protect water quality. The 4-inch-diameter plastic balls block sunlight from penetrating the 175-acre surface of the reservoir, preventing chemical reactions that can cause algae blooms and other problems. (AP Photo/Damian Dovarganes)
Reservoir Shade Balls
The Los Angeles Reservoir is covered with over 90 million black plastic balls in the Sylmar area of Los Angeles Wednesday, Aug. 12, 2015. The city has completed a program of covering open-air reservoirs with floating "shade balls" to protect water quality. The 4-inch-diameter plastic balls block sunlight from penetrating the 175-acre surface of the reservoir, preventing chemical reactions that can cause algae blooms and other problems. (AP Photo/Damian Dovarganes)
Reservoir Shade Balls
Over 90 million plastic balls cover the Los Angeles Reservoir in the Sylmar area of Los Angeles Wednesday, Aug. 12, 2015. The city has completed a program of covering open-air reservoirs with floating "shade balls" to protect water quality. The 4-inch-diameter plastic balls block sunlight from penetrating the 175-acre surface of the reservoir, preventing chemical reactions that can cause algae blooms and other problems. (AP Photo/Damian Dovarganes)
Reservoir Shade Balls
A "shade ball" is displayed on the outer banks of the Los Angeles Reservoir, which is covered with over 90 million of the black plastic balls in the Sylmar area of Los Angeles Wednesday, Aug. 12, 2015. The city has completed a program of covering open-air reservoirs with the floating "shade balls" to protect water quality. The 4-inch-diameter plastic balls block sunlight from penetrating the 175-acre surface of the reservoir, preventing chemical reactions that can cause algae blooms and other problems. (AP Photo/Damian Dovarganes)
Eric Garcetti
In this Monday, Aug. 10, 2015 photo provided by the Los Angeles Department of Water and Power, Los Angeles Mayor Eric Garcetti, in suit at center rear, and LADWP workers deposit the final batch of over 90 million "shade balls" into the Los Angeles Reservoir in the Sylmar area of Los Angeles. The plastic balls were placed to protect water quality and to save 300 million gallons of water a year from evaporation. (Art Mochizuki/Los Angeles Department of Water and Power via AP)
Reservoir Shade Balls
The Los Angeles Reservoir is covered with over 90 million black plastic balls in the Sylmar area of Los Angeles Wednesday, Aug. 12, 2015. The city has completed a program of covering its open-air reservoirs with floating, 4-inch diameter "shade balls" to protect water quality by blocking sunlight from penetrating the 175-acre surface of the reservoir, preventing chemical reactions that can cause algae blooms and other problems. (AP Photo/Damian Dovarganes)