Mesmerising moment thousands of 'shade balls' released into water supply
Tens of thousands of 'shade balls' have been released into a California reservoir to combat the state's drought, creating mesmerising images and video.
The black balls block sunlight and reducing evaporation, which helps to maintain water quality.
Footage of the balls cascading down a slope into the Sylmar reservoir in Los Angeles has proven a huge hit online.
The balls were deployed by the City of Los Angeles to prevent sunlight reacting with chlorine and bromide in the water and creating bromate - a suspected carcinogen.
A relatively cheap and long-lasting solution, the balls are weighted with water so that they remain in place, and they can last 10 years before getting recycled.
They have also been used in the past to keep birds out of waterways near airports.
The video was initially posted to YouTube by Las Virgenes Municipal Water District, where it has racked up around 22,000 views in just over a day.