LA reservoir covered with balls to protect water

LOS ANGELES (AP) — Hundreds of thousands of shimmering black plastic balls were dumped into one of the city’s last open-air reservoirs to prevent a sunlight-fueled chemical reaction that can harm the water supply.
Workers on Monday 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.
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 plastic spheres are ”a cost effective method of creating shade without elaborate construction, parts, labor or maintenance,“ the department said in a statement.
The balls are a temporary fix while the city completes an underground water storage project to replace the open-air reservoirs within several years.