The City of Los Angeles has released 96 million black plastic balls into its reservoirs in an effort to protect the remaining potable water during one of the worst droughts on record. The polyethylene balls, which are 4 inches in diameter, float on the surface of the water and cast shade below, reducing losses from evaporation. According to the Washington Post, the project is expected to reduce water loss by around 300 million gallons a year.
The shade balls were released at a time when California’s long drought had seen water supplies dwindle to dangerous lows. Governor Jerry Brown was even moved to declare a state of emergency in January 2015. Proponents of the shade ball program hoped to reduce the loss of the remaining water, as well as to comply with Environmental Protection Agency requirements that all reservoirs be protected with some kind of light barrier.
The floating balls are much more efficient and economical than tarps, especially when covering sites that range in size up to 175 acres. According to local news agency ABC7, using the balls cut the projected cost of covering the water down from $300 million to just under $35 million. The balls are recyclable, and they are expected to last up to 10 years without needing to be replaced.
The 96 million shade balls have another purpose. By blocking ultraviolet light from interacting with the chlorine in the reservoir, the balls prevent the formation of the potential carcinogen bromine, which can concentrate in depleted reservoirs and make the remaining water unfit for use. The balls also reduce contamination from animals, especially birds, according to Bloomberg.
California has responded to its debilitating drought with a number of creative approaches, but none seems quite as quirky as the release of nearly 100 million plastic balls into the drinking water. While tests lend weight to the claim that hundreds of millions of gallons of water can be saved with the measure, the City of Los Angeles, which consumed 13.6 billion gallons in June 2015 alone, still needs rain to recharge its water supply.