Which measure did los angeles take as a result of severe droughts?

The city of Los Angeles released 96 million "shade balls" into the Los Angeles Reservoir. These will serve to shield the water from the sun's heat in order to reduce evaporation and prevent algal and bacterial growth so no toxic substances are produced in the water. The balls reduce evaporation by 85%-90% so will save a lot of water yearly.

The correct answer would be lost aquila