The drought in California may have more to do mismanagement and inefficient allocation of the state's water supply, but it's led to the land of Hippies adopting some unusual strategies for water preservation. What specifically are they doing? Filling their reservoirs with black plastic balls:
On Monday Los Angeles Mayor Eric Garcetti supervised the latest onslaught of 4-inch black plastic balls, bringing the total count to 96 million in the 175-acre reservoir. Located in Sylmar, the reservoir holds up to 3.3 billion gallons, enough to supply the city with drinking water for up to three weeks. The city says the balls will shade and cool the water, reducing evaporation from the reservoir and making it less susceptible to algae, bacterial growth, and chemical reactions that can produce harmful substances. ... The balls cost 36 cents each, for a total of $34.5 million. The utility has been testing the concept since 2008, reporting that shade balls reduce evaporation by 85 to 90 percent. That should equate to saving nearly 300 million gallons a year, enough to provide drinking water for 8,100 people, said Los Angeles City Council member Mitchell Englander. The balls also inhibit microorganism growth, reducing the treatment the water must undergo through other means. That could save the city $250 million over time, said Garcetti.
I'm a bit surprised as to why they're using black balls specifically, which would seem to absorb more heat than white-coloured balls.
This approach might save them some money, but I wonder if turning to India might provide the state with alternative, even-more-Hippy-compatible approaches to reducing evaporation. What's India doing? It's installing solar panels on top of its canals
Two quantifiable benefits of building solar power plants on canals as against conventional ground-mounted systems were widely reported — the amount of land it would save and also the amount of water it would save, which would have otherwise been lost due to evaporation.
The first project back in 2012 wound up being somewhat more expensive than traditional land-based solar, but at least some of that seems to be due to the small-scale size of the initial project and should diminish as the scale of this goes up.
India has also been building floating solar installations on its lakes, which perhaps more closely approximates California filling its reservoirs with plastic balls. Personally I think, whether you would install solar panels on canals or reservoirs, either would look better than the current approach of dumping those plastic balls on reservoirs.