One year later, the shade balls dumped in the Los Angeles Reservoir have proven to be successful in saving water, according to the L.A. Department of Water and Power. In August of last year, L.A. officials released an additional 20,000 balls into the Los Angeles Reservoir, bringing the total number of balls in use to 96 million. The 36-cent plastic balls were designed to block sunlight, preventing chemical reactions that can cause harmful algae blooms.