Los Angeles reservoir covered with plastic balls to protect the water

June 2008

U.S. Water News Online

LOS ANGELES — Hundreds of thousands of shimmering black plastic balls were dumped into one of the city's last remaining open-air reservoirs recently to prevent a sunlight-fueled chemical reaction that can harm the water supply.

Workers unleashed 400,000 of the hollow, 4-inch "shade balls" down a slope to cover the surface of the Ivanhoe Reservoir, which provides water to parts of downtown, central and south Los Angeles.

The result resembled a giant tub of bowling balls or a piece of large-scale conceptual art.

Earlier this year, the Los Angeles Department of Water and Power drained two of its six remaining open-air reservoirs because a rare sunlight-and-chlorine reaction tainted the water with bromate, a cancer-causing chemical. The amounts were small and didn't violate federal water regulations, but the water was dumped as a precaution.

The small spheres are "a cost effective method of creating shade without elaborate construction, parts, labor or maintenance," the DWP said in a statement.

The balls were a temporary fix while the city completes an underground water storage project in Griffith Park to replace the open-air reservoirs.