The Los Angeles Department of Water and Power dropped the ball ... literally! They dumped over 400,000 small plastic balls into the Ivanhoe Reservoir in order to protect the drinking water supply:
The water needs to be shaded because when sunlight mixes with the bromide and chlorine in Ivanhoe's water, the carcinogen bromate forms, said Pankaj Parekh, DWP's director for water quality compliance. Bromide is naturally present in groundwater and chlorine is used to kill bacteria, he said, but sunlight is the final ingredient in the potentially harmful mix. [...]
A tarp would have been too expensive and a metal cover would take too long to install, especially in a year of drought. So one of the DWP's biologists, Brian White, suggested "bird balls," commonly used by airports to prevent birds from congregating in wet areas alongside runways.
Francisco Vara-Orta of the Los Angeles Times has the story: Link (with video)
(Photo: Irfan Khan / LA Times)