Los Angeles has filled a large reservoir with 96 million "shade balls" that could become a much needed lifeline amidst California's continuing drought.
On Monday, mayor Eric Garcetti completed a $34.5 million initiative involving the use of "shade balls" to conserve the city's precious reserve of water.
The aim of the black balls is three-fold, to slow evaporation, preserve water quality and prevent wildlife from contaminating the water.
It has taken the Los Angeles Department of Water and Power (LADWP) department months to release 96 million balls into the reservoir with the last 20,000 balls being released on Monday.
Each black sphere costs $0.36 (£0.23) and the collective effect should preserve L.A. Reservoir's 3.3 billion gallons of water, which LADWP say is enough to supply the entire city with water for three weeks.
The balls work by deflecting UV rays and preventing harmful chemical reactions between chlorine -- used as a disinfectant in water -- and bromide, which occurs naturally in the ground. In sunlight, both compounds can react to form a carcinogen known as bromate.
City officials say the initiative could save LA up to $250 million.
Council member Mitchell Englander put the cost-saving measures in context of the number of residents that will benefit from the scheme.
“In addition to cutting back on the need to chemically treat our water to prevent natural occurrences like algae, these shade balls are a cost-effective way to reduce evaporation each year by nearly 300 million gallons, enough to provide drinking water for 8,100 people for a full year.”
The idea came from a retired biologist who was observing “bird balls” in ponds along airfield runways.