During the week of August 10, Los Angeles city workers filled the Los Angeles (LA) Reservoir with 96 million 4-inch spherical balls made of high density polyethylene, colored wtih carbon black and ballasted by potable water (filled with some water to keep them from blowing away). According to the manufacturer’s website these balls are called “conservation balls” and their purpose is to keep water from evaporating from large reservoirs. The company says they can be applied at municipalities to reduce water evaporation in reservoirs, ski areas to reduce evaporation in reservoirs, water treatment facilities to reduce odor, in the mining Industry, and in the petroleum Industry. The company says the balls address evaporation by providing a floating cover on the reservoir taking up approximately 90% of the surface area and simultaneously preventing ultra violet (UV) rays from reaching the water and therefore reducing algae.
The shade ball project cost about $35 million, but according to officials saved them $250 million when compared to building a cover to shade the reservoir. It is reported to save about 300 million gallons of water annualy from evaporation. But LA officials also said that they have another purpose – to shade the water from UV so that bromates don’t form. Bromates are disinfection byproducts that form when bromide in the water reacts with UV and a disinfectant (oxidizer) like ozone or chlorine. And, LA has been using the shade balls in two other reservoirs since 2008, without much of a peep or concern to this point. What was difference about this time?
Concerns have been raised over the use of the shade balls – some of this has now been discussed by LA Officials and the company and others remain unresolved. The biggest problem I saw when this story came out is that the municipality did not anticipate questions and issues (=communication fail). The awareness of the potential harm from plastic in our environment (and specifcially our waterways) is probably higher than ever. The shade balls were instantly touted as a great cost-saving solution to covering the entire 175-acre surface of the reservoir. They even made a video to be released and a press release. No one seemed to have the foresight to see there would be questions about leaching from the plastic and the potential for degredation and microplastic formation. We study plastic fragmentation in my lab – we expose polymers (one of them polyethylene) to UV light and then see if fragmentation occurs. We are still working on studying time frames and synergy of conditions like abrasion and UV exposure, but this looks like one big plastic fragmentation experiment to me. I would go out in one year and sample the water for microplastic. And do so every so often after that. That means the 2008 reservoir could be sampled now. While we know that plastic does not biodegrade, we do also know that the ocean contains (and sometimes spits out) microplastic particles that were once larger items. But we don’t fully understand the timeframe and mechanisms for that transformation yet.
What do you think of this as a solution to Californias drought issues? If a municipality has to find a solution quickly and for the least cost, what else can they do? Could other methods or solutions could be combined with this one? Can you think of any policy-related solutions?