The agency started dumping thousands of floating plastic balls into Ivanhoe Reservoir -- the dwarf sibling next door to Silver Lake Reservoir, the neighborhood's crown jewel -- to protect the drinking water supply needed for summer.
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.
Resembling a stream of oversized caviar, the black balls rolled thunderously down the reservoir's slopes. "Water quality doesn't get more exciting than this," Marina J.F. Busatto, a DWP biologist, said smiling.
Ivanhoe and Elysian reservoirs will be blanketed by about 3 million balls each for about four years, Parekh said.
There's a video, but their embedded player is stupid. It seems to be not on Youtube yet.