The final tranche of 96m black plastic shade balls is released into the Los Angeles reservoir at Sylmar, to help improve water quality and prevent evaporation. The LA water and power department began pouring the balls into the water two months ago, as can be seen in the first clip, and the final balls are introduced this week.

The idea was conceived in 2007 in an effort to prevent the reservoir becoming contaminated with bromate, a substance formed when chemicals in the water react with sunlight. The balls are a relatively low-cost solution, at $34.5m, and are expected to save about $250m over 10 years, and prevent 300m gallons of water evaporating

