Those water balls that Los Angles sent into Sylmar Reservoir got misinterpreted wildly, with much gushing about how the water balls slow evaporation. That’s not their primary purpose. The balls prevent treated water from “biodegrading into undrinkable water” due to UV rays from the sun. Evaporation is very much a secondary benefit.
The balls last upwards of 25 years (Hmm, how do they plan on rounding up 96 million spent black water balls 25 years from now?) are expensive, about $1,500 an acre foot. This is considering less than the other alternative, a huge floating black mat that is $3,700 per acre foot, but still hardly cheap.
Aguanomics, which is about the economics of water, says LADWP and other water agencies need to focus on reducing demand, stop making it cheap for homeowners to water lawns, and in general, raise prices in a smart way so usage drops. Astonishingly, tiered pricing is illegal in California. Here in Las Vegas, tiered pricing is very much in use, and if you have a grass lawn, may get a whopping water bill in he summer. We recently moved to Vegas, replaced the grass with drip irrigation xeriscaping, put a floating cover on the pool – and our water bill for last month, when it was definitely hot, was a mere $32. Conservation is possible.
Indeed, if you think the balls are ONLY about evaporation, then you will see them on non-treated water reservoirs, but… no sign of that.
Bottom Line: Water managers need to be clearer about why and when they are spending ratepayer money. Even better, they should implement both demand reducing and supply augmenting policies in times of water scarcity (or all the time).