Why Are 96,000,000 Black Balls on This Reservoir?
Starting in mid-2008, the Los Angeles Department of Water and Power (LADWP) put about 400,000 balls in the Ivanhoe reservoir with the main objective of preventing the formation of a carcinogenic chemical, bromate, which forms when naturally occurring bromine reacts with chlorine in sunlight.[1][3] In the original release by the LADWP, there is no mention of water conservation as an objective and the project was planned for a five year life span, until a Griffith Park project was completed. The reduction in evaporation led to an estimated savings of about 1.1 billion liters (290 million gallons) of water in one year.[1]
In 2014 and 2015, the LADWP put 96 million shade balls onto its largest reservoir (Las Virgenes)[4] in response to the United States Environmental Protection Agency's surface water treatment rule,[5] which requires large reservoirs of treated water to be covered.[6][7] The LADWP says that in addition to reducing evaporation, they also reduce UV radiation by-products and algae growth.[8] The balls saved 1.7 million cubic metres of water from evaporating during their deployment from August 2015 to March 2017. However they required 2.9 million cubic metres of water in their manufacture. Nevertheless, the balls have a lifespan of ten years, and the plastic may be reused after that.[9]
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